At Mercer Lake, Mercer County Park Naturalist Christy Athmejvar led a group of us on a tour of the lake’s nooks and crannies, wisely advising us to keep our binoculars handy as she spied cool critters and plant life.
In one hidden cove, as we passed a beaver dam, we saw 14 painted turtles basking on a log and three bullfrogs staring ahead with their bulbous eyes and wide mouths just above the water.
Paddling near the shoreline, Christy would quickly interrupt herself to point out a red-winged blackbird or an American goldfinch soaring above or, to her delight, a double-crested cormorant tucked in the water with only its head and long, curved neck visible.
Toward the end of the tour, her visual sweeps of the treetops scored the highlights of the day – two bald eagles. We kept our binoculars trained on the majestic birds as we bobbed in the kayaks, savoring our lucky finds.
A day later, it was time to join the sojourn that was completing its 24th annual, eight-day trip down sections of the Delaware River.
Fortunate that a thunderstorm threat never materialized, our sojourners, ranging from youth groups to seasoned veterans of the journey, paddled the warm, gentle waters of Crosswicks and Watson creeks on an eight-mile round-trip to the Tulpehacking Nature Center in Hamilton, New Jersey.
We started and finished at Bordentown Beach at the confluence of the Delaware River and Crosswicks Creek. Along the way, we struck up conversations and at times joined our kayaks and canoes, drifting with the tide as we heard presentations about the Abbott Marshlands.
The talks focused on successful efforts to preserve and expand the marshlands, their rich cultural and historic legacy, and the support they provide for more than 1,200 species of plants and wildlife.
Whether on water or land, head out to some of the natural attractions of the Delaware River Watershed to get a better sense for why its restoration is so important to EPA and its partners.
At Mercer Lake, Mercer County Park Naturalist Christy Athmejvar led a group of us on a tour of the lake’s nooks and crannies, wisely advising us to keep our binoculars handy as she spied cool critters and plant life.
In one hidden cove, as we passed a beaver dam, we saw 14 painted turtles basking on a log and three bullfrogs staring ahead with their bulbous eyes and wide mouths just above the water.
Paddling near the shoreline, Christy would quickly interrupt herself to point out a red-winged blackbird or an American goldfinch soaring above or, to her delight, a double-crested cormorant tucked in the water with only its head and long, curved neck visible.
Toward the end of the tour, her visual sweeps of the treetops scored the highlights of the day – two bald eagles. We kept our binoculars trained on the majestic birds as we bobbed in the kayaks, savoring our lucky finds.
A day later, it was time to join the sojourn that was completing its 24th annual, eight-day trip down sections of the Delaware River.
Fortunate that a thunderstorm threat never materialized, our sojourners, ranging from youth groups to seasoned veterans of the journey, paddled the warm, gentle waters of Crosswicks and Watson creeks on an eight-mile round-trip to the Tulpehacking Nature Center in Hamilton, New Jersey.
We started and finished at Bordentown Beach at the confluence of the Delaware River and Crosswicks Creek. Along the way, we struck up conversations and at times joined our kayaks and canoes, drifting with the tide as we heard presentations about the Abbott Marshlands.
The talks focused on successful efforts to preserve and expand the marshlands, their rich cultural and historic legacy, and the support they provide for more than 1,200 species of plants and wildlife.
Whether on water or land, head out to some of the natural attractions of the Delaware River Watershed to get a better sense for why its restoration is so important to EPA and its partners.
Perseid meteor on the morning of August 12, 2017, from Hrvoje Crnjak in Šibenik, Croatia. Notice the variations in brightness and color throughout, and the little “pop” of brightness toward the bottom. A brightness “pop” like that comes from a clump of vaporizing debris. Thank you, Hrvoje! Click for more 2017 Perseids.
No matter where you live worldwide, the 2018 Perseid meteor shower will probably produce the greatest number of meteors on the mornings of August 11, 12 and 13. In a dark, moonless sky, this annual shower often produces 50 or more meteors per hour. And this year, in 2018, there will be no moonlight to ruin the show.
It should be an awesome year to watch the Perseids!
In the Northern Hemisphere, we rank the August Perseids as an all-time favorite meteor shower of every year. For us, this major shower takes place during the lazy, hazy days of summer, when many families are on vacation. And what could be more luxurious than taking a siesta in the heat of the day and watching this summertime classic in the relative coolness of night?
People tend to focus on the peak mornings of the shower and that’s entirely appropriate. But meteors in annual showers – which come from streams of debris left behind in space by comets – typically last weeks, not days. Perseid meteors have been streaking across our skies since around July 17. We’ll see Perseids for 10 days or so after the peak mornings on August 11, 12 and 13. What’s more, the Perseids tend to build up gradually, yet fall off rapidly. So it’s often wise to watch in the couple of weeks prior to the peak … but not this year.
We can’t start watching for Perseids in early August in 2018, because the moon is in the way.
This is about the moon phase you’ll see on August 1, 2018. It’s a waning gibbous moon, rising in late evening, casting its light around in the peak hours for watching meteors between midnight and dawn. Wait until about mid-week next week – say, around August 7 or 8, 2018 – to start any serious meteor watching. Between now and then, look for the brightest Perseids in moonlight! Photo by Lunar101-MoonBook.
When and how should I watch the Perseid meteor shower in 2018? The best time to watch most meteor showers is between midnight and dawn, and the Perseids are no exception. The best mornings are probably August 11, 12 and 13. The best skies are those far from city lights.
Between early August and the peak mornings, you might catch a Perseid meteor in moonlight. New moon will be August 11, but don’t think you have to wait until then to see any meteors. The moon will be a slim crescent in the days prior to August 11, and a crescent moon is easy to blot out by sitting in the shadow of a tree or building. Plus, as the days leading up to new moon pass, the moon will be rising closer and closer to the time of sunrise.
Also remember, the the Delta Aquarid meteor shower is still rambling along steadily. You’ll see mostly Perseids but also a few Delta Aquarids in the mix.
No matter how many meteors you see, you might see something, and it might be a lot of fun.
Composite of 12 images acquired on August 13 by Felix Zai in Toronto. He wrote: “Perseid meteor shower gave a good show even though the moon light drown out most of the fainter ones. A huge fireball was captured in this photo.” Thanks, Felix! By the way, it’s only in a meteor “storm” that you’d see this many meteors at once. Even in a rich shower, you typically see only 1 or 2 meteors at a time. Click for more 2017 Perseids.
Don’t rule out early evenings, either. In a typical year, although the meteor numbers increase after midnight, the Perseid meteors still start to fly at mid-to-late evening from northerly latitudes. South of the equator, the Perseids start to streak the sky around midnight. If fortune smiles upon you, the evening hours might offer you an earthgrazer – a looooong, slow, colorful meteor traveling horizontally across the evening sky. Earthgrazer meteors are rare but memorable. Perseid earthgrazers appear before midnight, when the radiant point of the shower is close to the horizon.
From mid-northern latitudes, the constellation Perseus, the stars Capella and Aldebaran, and the Pleiades cluster light up the northeast sky in the wee hours after midnight on August nights. The meteors radiate from Perseus.
Here’s a cool binocular object to look for while you’re watching the meteors. The constellation Cassiopeia points out the famous Double Cluster in northern tip of the constellation Perseus. Plus, the Double Cluster nearly marks the radiant of the Perseid meteor shower. Photo by Flickr user madmiked
General rules for Perseid-watching. No special equipment, or knowledge of the constellations, needed.
Find a dark, open sky to enjoy the show. An open sky is essential because these meteors fly across the sky in many different directions and in front of numerous constellations.
Give yourself at least an hour of observing time, for these meteors in meteor showers come in spurts and are interspersed with lulls. Remember, your eyes can take as long as 20 minutes to adapt to the darkness of night. So don’t rush the process.
Know that the meteors all come from a single point in the sky. If you trace the paths of the Perseid meteors backwards, you’d find they all come from a point in front of the constellation Perseus. Don’t worry about which stars are Perseus. Just enjoying knowing and observing that they all come from one place on the sky’s dome.
Enjoy the comfort of a reclining lawn chair. Bring along some other things you might enjoy also, like a thermos filled with a hot drink.
Remember … all good things come to those who wait. Meteors are part of nature. There’s no way to predict exactly how many you’ll see on any given night. Find a good spot, watch, wait.
What’s the source of the Perseid meteor shower? Every year, from around July 17 to August 24, our planet Earth crosses the orbital path of Comet Swift-Tuttle, the parent of the Perseid meteor shower. Debris from this comet litters the comet’s orbit, but we don’t really get into the thick of the comet rubble until after the first week of August. The bits and pieces from Comet Swift-Tuttle slam into the Earth’s upper atmosphere at some 130,000 miles (210,000 km) per hour, lighting up the nighttime with fast-moving Perseid meteors.
If our planet happens to pass through an unusually dense clump of meteoroids – comet rubble – we’ll see an elevated number of meteors. We can always hope!
Comet Swift-Tuttle has a very eccentric – oblong – orbit that takes this comet outside the orbit of Pluto when farthest from the sun, and inside the Earth’s orbit when closest to the sun. It orbits the sun in a period of about 133 years. Every time this comet passes through the inner solar system, the sun warms and softens up the ices in the comet, causing it to release fresh comet material into its orbital stream.
Comet Swift-Tuttle last reached perihelion – closest point to the sun – in December 1992 and will do so next in July 2126.
The radiant point for the Perseid meteor shower is in the constellation Perseus. But you don’t have to find a shower’s radiant point to see meteors. Instead, the meteors will be flying in all parts of the sky.
What is the radiant point for the Perseid meteor shower? If you trace all the Perseid meteors backward, they all seem to come from the constellation Perseus, near the famous Double Cluster. Hence, the meteor shower is named in the honor of the constellation Perseus the Hero.
However, this is a chance alignment of the meteor shower radiant with the constellation Perseus. The stars in Perseus are light-years distant while these meteors burn up about 100 kilometers (60 miles) above the Earth’s surface. If any meteor survives its fiery plunge to hit the ground intact, the remaining portion is called a meteorite. Few – if any – meteors in meteor showers become meteorites, however, because of the flimsy nature of comet debris. Most meteorites are the remains of asteroids.
In ancient Greek star lore, Perseus is the son of the god Zeus and the mortal Danae. It is said that the Perseid shower commemorates the time when Zeus visited Danae, the mother of Perseus, in a shower of gold.
Perseid meteor on the morning of August 12, 2017, from Hrvoje Crnjak in Šibenik, Croatia. Notice the variations in brightness and color throughout, and the little “pop” of brightness toward the bottom. A brightness “pop” like that comes from a clump of vaporizing debris. Thank you, Hrvoje! Click for more 2017 Perseids.
No matter where you live worldwide, the 2018 Perseid meteor shower will probably produce the greatest number of meteors on the mornings of August 11, 12 and 13. In a dark, moonless sky, this annual shower often produces 50 or more meteors per hour. And this year, in 2018, there will be no moonlight to ruin the show.
It should be an awesome year to watch the Perseids!
In the Northern Hemisphere, we rank the August Perseids as an all-time favorite meteor shower of every year. For us, this major shower takes place during the lazy, hazy days of summer, when many families are on vacation. And what could be more luxurious than taking a siesta in the heat of the day and watching this summertime classic in the relative coolness of night?
People tend to focus on the peak mornings of the shower and that’s entirely appropriate. But meteors in annual showers – which come from streams of debris left behind in space by comets – typically last weeks, not days. Perseid meteors have been streaking across our skies since around July 17. We’ll see Perseids for 10 days or so after the peak mornings on August 11, 12 and 13. What’s more, the Perseids tend to build up gradually, yet fall off rapidly. So it’s often wise to watch in the couple of weeks prior to the peak … but not this year.
We can’t start watching for Perseids in early August in 2018, because the moon is in the way.
This is about the moon phase you’ll see on August 1, 2018. It’s a waning gibbous moon, rising in late evening, casting its light around in the peak hours for watching meteors between midnight and dawn. Wait until about mid-week next week – say, around August 7 or 8, 2018 – to start any serious meteor watching. Between now and then, look for the brightest Perseids in moonlight! Photo by Lunar101-MoonBook.
When and how should I watch the Perseid meteor shower in 2018? The best time to watch most meteor showers is between midnight and dawn, and the Perseids are no exception. The best mornings are probably August 11, 12 and 13. The best skies are those far from city lights.
Between early August and the peak mornings, you might catch a Perseid meteor in moonlight. New moon will be August 11, but don’t think you have to wait until then to see any meteors. The moon will be a slim crescent in the days prior to August 11, and a crescent moon is easy to blot out by sitting in the shadow of a tree or building. Plus, as the days leading up to new moon pass, the moon will be rising closer and closer to the time of sunrise.
Also remember, the the Delta Aquarid meteor shower is still rambling along steadily. You’ll see mostly Perseids but also a few Delta Aquarids in the mix.
No matter how many meteors you see, you might see something, and it might be a lot of fun.
Composite of 12 images acquired on August 13 by Felix Zai in Toronto. He wrote: “Perseid meteor shower gave a good show even though the moon light drown out most of the fainter ones. A huge fireball was captured in this photo.” Thanks, Felix! By the way, it’s only in a meteor “storm” that you’d see this many meteors at once. Even in a rich shower, you typically see only 1 or 2 meteors at a time. Click for more 2017 Perseids.
Don’t rule out early evenings, either. In a typical year, although the meteor numbers increase after midnight, the Perseid meteors still start to fly at mid-to-late evening from northerly latitudes. South of the equator, the Perseids start to streak the sky around midnight. If fortune smiles upon you, the evening hours might offer you an earthgrazer – a looooong, slow, colorful meteor traveling horizontally across the evening sky. Earthgrazer meteors are rare but memorable. Perseid earthgrazers appear before midnight, when the radiant point of the shower is close to the horizon.
From mid-northern latitudes, the constellation Perseus, the stars Capella and Aldebaran, and the Pleiades cluster light up the northeast sky in the wee hours after midnight on August nights. The meteors radiate from Perseus.
Here’s a cool binocular object to look for while you’re watching the meteors. The constellation Cassiopeia points out the famous Double Cluster in northern tip of the constellation Perseus. Plus, the Double Cluster nearly marks the radiant of the Perseid meteor shower. Photo by Flickr user madmiked
General rules for Perseid-watching. No special equipment, or knowledge of the constellations, needed.
Find a dark, open sky to enjoy the show. An open sky is essential because these meteors fly across the sky in many different directions and in front of numerous constellations.
Give yourself at least an hour of observing time, for these meteors in meteor showers come in spurts and are interspersed with lulls. Remember, your eyes can take as long as 20 minutes to adapt to the darkness of night. So don’t rush the process.
Know that the meteors all come from a single point in the sky. If you trace the paths of the Perseid meteors backwards, you’d find they all come from a point in front of the constellation Perseus. Don’t worry about which stars are Perseus. Just enjoying knowing and observing that they all come from one place on the sky’s dome.
Enjoy the comfort of a reclining lawn chair. Bring along some other things you might enjoy also, like a thermos filled with a hot drink.
Remember … all good things come to those who wait. Meteors are part of nature. There’s no way to predict exactly how many you’ll see on any given night. Find a good spot, watch, wait.
What’s the source of the Perseid meteor shower? Every year, from around July 17 to August 24, our planet Earth crosses the orbital path of Comet Swift-Tuttle, the parent of the Perseid meteor shower. Debris from this comet litters the comet’s orbit, but we don’t really get into the thick of the comet rubble until after the first week of August. The bits and pieces from Comet Swift-Tuttle slam into the Earth’s upper atmosphere at some 130,000 miles (210,000 km) per hour, lighting up the nighttime with fast-moving Perseid meteors.
If our planet happens to pass through an unusually dense clump of meteoroids – comet rubble – we’ll see an elevated number of meteors. We can always hope!
Comet Swift-Tuttle has a very eccentric – oblong – orbit that takes this comet outside the orbit of Pluto when farthest from the sun, and inside the Earth’s orbit when closest to the sun. It orbits the sun in a period of about 133 years. Every time this comet passes through the inner solar system, the sun warms and softens up the ices in the comet, causing it to release fresh comet material into its orbital stream.
Comet Swift-Tuttle last reached perihelion – closest point to the sun – in December 1992 and will do so next in July 2126.
The radiant point for the Perseid meteor shower is in the constellation Perseus. But you don’t have to find a shower’s radiant point to see meteors. Instead, the meteors will be flying in all parts of the sky.
What is the radiant point for the Perseid meteor shower? If you trace all the Perseid meteors backward, they all seem to come from the constellation Perseus, near the famous Double Cluster. Hence, the meteor shower is named in the honor of the constellation Perseus the Hero.
However, this is a chance alignment of the meteor shower radiant with the constellation Perseus. The stars in Perseus are light-years distant while these meteors burn up about 100 kilometers (60 miles) above the Earth’s surface. If any meteor survives its fiery plunge to hit the ground intact, the remaining portion is called a meteorite. Few – if any – meteors in meteor showers become meteorites, however, because of the flimsy nature of comet debris. Most meteorites are the remains of asteroids.
In ancient Greek star lore, Perseus is the son of the god Zeus and the mortal Danae. It is said that the Perseid shower commemorates the time when Zeus visited Danae, the mother of Perseus, in a shower of gold.
To most of us, dust is something to be cleaned up, washed off or wiped away. But the tiny particles that float about and settle on surfaces play an important role in a variety of processes on Earth and across the solar system. So put away that feather duster for a few moments, as we share with you 10 things to know about dust.
1. Dust doesn’t mean dirty, it means tiny
Not all of what we call “dust” is made of the same stuff. Dust in your home generally consists of things like particles of sand and soil, pollen, dander (dead skin cells), pet hair, furniture fibers and cosmetics. But in space, dust can refer to any sort of fine particles smaller than a grain of sand. Dust is most commonly bits of rock or carbon-rich, soot-like grains, but in the outer solar system, far from the sun’s warmth, it’s also common to find tiny grains of ice as well. Galaxies, including our Milky Way, contain giant clouds of fine dust that are light years across – the ingredients for future generations of planetary systems like ours.
Dramatic plumes, both large and small, spray water ice particles and vapor along the famed “tiger stripes” near the south pole of Saturn’s moon Enceladus. Image via NASA/JPL/Space Science Institute.
2. Some are big, some are small (and big ones tend to fall)
Dust grains come in a range of sizes, which affects their properties. Particles can be extremely tiny, from only a few tens of nanometers (mere billionths of a meter) wide, to nearly a millimeter wide. As you might expect, smaller dust grains are more easily lifted and pushed around, be it by winds or magnetic, electrical and gravitational forces. Even the gentle pressure of sunlight is enough to move smaller dust particles in space. Bigger particles tend to be heavier, and they settle out more easily under the influence of gravity.
For example, on Earth, powerful winds can whip up large amounts of dust into the atmosphere. While the smaller grains can be transported over great distances, the heavier particles generally sink back to the ground near their source. On Saturn’s moon Enceladus, jets of icy dust particles spray hundreds of miles up from the surface; the bigger particles are lofted only a few tens of miles (or kilometers) and fall back to the ground, while the finest particles escape the moon’s gravity and go into orbit around Saturn to create the planet’s E ring.
Dust in the spiral galaxy M74 appears red in this image from NASA’s Spitzer Space Telescope. Data from Spitzer provided evidence that supernovae – the explosive deaths of massive stars – act as “dust factories,” seeding galaxies with cosmic dust particles. Image via NASA/JPL-Caltech/STScI.
3. It’s EVERYWHERE
Generally speaking, the space between the planets is pretty empty, but not completely so. Particles cast off by comets and ground up bits of asteroids are found throughout the solar system. Take any volume of space half a mile (1 kilometer) on a side, and you’d average a few micron-sized particles (grains the thickness of a red blood cell).
Dust in the solar system was a lot more abundant in the past. There was a huge amount of it present as the planets began to coalesce out of the disk of material that formed the sun. In fact, motes of dust gently sticking together were likely some of the earliest seeds of the planet-building process. But where did all that dust come from, originally? Some of it comes from stars like our sun, which blow off their outer layers in their later years. But lots of it also comes from exploding stars, which blast huge amounts of dust and gas into space when they go boom.
This mosaic of images from NASA’s Galileo spacecraft shows Jupiter’s ring system, which was only discovered after spacecraft had flown past the planet and could see the rings backlit by the sun. Image via NASA/JPL-Caltech/Cornell University.
4. From a certain point of view
Dust is easier to see from certain viewing angles. Tiny particles scatter light depending on how big their grains are. Larger particles tend to scatter light back in the direction from which it came, while very tiny particles tend to scatter light forward, more or less in the direction it was already going. Because of this property, structures like planetary rings made of the finest dusty particles are best viewed with the sun illuminating them from behind. For example, Jupiter’s rings were only discovered after the Voyager 1 spacecraft passed by the planet, where it could look back and see them backlit by the sun. You can see the same effect looking through a dusty windshield at sunset; when you face toward the sun, the dust becomes much more apparent.
Side-by-side movies show how dust enveloped the red planet in 2018, courtesy of NASA’s Mars Reconnaissance Orbiter. Image via NASA/JPL-Caltech/MSSS.
5. Dust storms are common on Mars
Local dust storms occur frequently on Mars, and occasionally grow or merge to form regional systems, particularly during the southern spring and summer, when Mars is closest to the Sun. On rare occasions, regional storms produce a dust haze that encircles the planet and obscures surface features beneath. A few of these events may become truly global storms, such as one in 1971 that greeted the first spacecraft to orbit Mars, NASA’s Mariner 9. In mid-2018, a global dust storm enshrouded Mars, hiding much of the Red Planet’s surface from view and threatening the continued operation of NASA’s uber long-lived Opportunity rover. We’ve also seen global dust storms in 1977, 1982, 1994, 2001 and 2007.
Dust storms will likely present challenges for future astronauts on the Red Planet. Although the force of the wind on Mars is not as strong as portrayed in an early scene in the movie The Martian, dust lofted during storms could affect electronics and health, as well as the availability of solar energy.
Sarharan dust is carried by winds to South America, where it helps fertilize the Amazon. Via NASA’s Goddard Space Flight Center.
6. Dust from the Sahara goes global
Earth’s largest, hottest desert is connected to its largest tropical rain forest by dust. The Sahara Desert is a near-uninterrupted brown band of sand and scrub across the northern third of Africa. The Amazon rain forest is a dense green mass of humid jungle that covers northeast South America. But after strong winds sweep across the Sahara, a dusty cloud rises in the air, stretches between the continents, and ties together the desert and the jungle.
This trans-continental journey of dust is important because of what is in the dust. Specifically, the dust picked up from the Bodélé Depression in Chad – an ancient lake bed where minerals composed of dead microorganisms are loaded with phosphorus. Phosphorus is an essential nutrient for plant proteins and growth, which the nutrient-poor Amazon rain forest depends on in order to flourish.
Saturn’s icy rings, backlit by the sun. The outer, bluish looking ring is composed entirely of icy dust particles sprayed into space by the moon Enceladus. Image via NASA/JPL-Caltech/SSI.
7. Rings and things
The rings of the giant planets contain a variety of different dusty materials. Jupiter’s rings are made of fine rock dust. Saturn’s rings are mostly pure water ice, with a sprinkling of other materials. (Side note about Saturn’s rings: While most of the particles are boulder-sized, there’s also lots of fine dust, and some of the fainter rings are mostly dust with few or no large particles.) Dust in the rings of Uranus and Neptune is made of dark, sooty material, probably rich in carbon.
Over time, dust gets removed from ring systems due to a variety of processes. For example, some of the dust falls into the planet’s atmosphere, while some gets swept up by the planets’ magnetic fields, and other dust settles onto the surfaces of the moons and other ring particles. Larger particles eventually form new moons or get ground down and mixed with incoming material. This means rings can change a lot over time, so understanding how the tiniest ring particles are being moved about has bearing on the history, origins and future of the rings.
Dark moon dust clings to the spacesuit of Apollo 17 astronaut Gene Cernan following an excursion on the lunar surface. Image via NASA.
8. Moon dust is clingy and might make you sick
So, dust is kind of a thing on the moon. When the Apollo astronauts visited the Moon, they found that lunar dust quickly coated their spacesuits and was difficult to remove. It was quite abrasive, causing wear on their spacesuit fabrics, seals and faceplates. It also clogged mechanisms like the joints in spacesuit limbs, and interfered with fasteners like zippers and Velcro. The astronauts also noted that it had a distinctive, pungent odor, not unlike gunpowder, and it was an eye and lung irritant.
Many of these properties apparently can be explained by the fact that lunar dust particles are quite rough and jagged. While dust particles on Earth get tumbled and ground by the wind into smoother shapes, this sort of weathering doesn’t happen so much on the moon. The roughness of moon dust grains makes it very easy for them to cling to surfaces and scratch them up. It also means they’re not the sort of thing you would want to inhale, as their jagged edges could damage delicate tissues in the lung.
Hubble Space Telescope image of comet ISON, taken in 2013. Image via NASA, ESA, and the Hubble Heritage Team (STScI/AURA).
9. Dust is what makes comets so pretty
Most comets are basically clods of dust, rock and ice. They spend most of their time far from the sun, out in the refrigerated depths of the outer solar system, where they’re peacefully dormant. But when their orbits carry them closer to the sun – that is, roughly inside the orbit of Jupiter – comets wake up. In response to warming temperatures, the ices on and near their surfaces begin to turn into gases, expanding outward and away from the comet, and creating focused jets of material in places. Dust gets carried away by this rapidly expanding gas, creating a fuzzy cloud around the comet’s nucleus called a coma. Some of the dust also is drawn out into a long trail – the comet’s tail.
Dust in our solar system is continually replenished by comets whizzing past the sun and the occasional asteroid collision, and it’s always being moved about, thanks to a variety of factors like the gravity of the planets and even the pressure of sunlight. Some of it even gets ejected from our solar system altogether.
With telescopes, we also observe dusty debris disks around many other stars. As in our own system, the dust in such disks should evolve over time, settling on planetary surfaces or being ejected, and this means the dust must be replenished in those star systems as well. So studying the dust in our planetary environs can tell us about other systems, and vice versa. Grains of dust from other planetary systems also pass through our neighborhood – a few spacecraft have actually captured and analyzed some them – offering us a tangible way to study material from other stars.
Bottom line: Ten facts about dust in space and on Earth.
To most of us, dust is something to be cleaned up, washed off or wiped away. But the tiny particles that float about and settle on surfaces play an important role in a variety of processes on Earth and across the solar system. So put away that feather duster for a few moments, as we share with you 10 things to know about dust.
1. Dust doesn’t mean dirty, it means tiny
Not all of what we call “dust” is made of the same stuff. Dust in your home generally consists of things like particles of sand and soil, pollen, dander (dead skin cells), pet hair, furniture fibers and cosmetics. But in space, dust can refer to any sort of fine particles smaller than a grain of sand. Dust is most commonly bits of rock or carbon-rich, soot-like grains, but in the outer solar system, far from the sun’s warmth, it’s also common to find tiny grains of ice as well. Galaxies, including our Milky Way, contain giant clouds of fine dust that are light years across – the ingredients for future generations of planetary systems like ours.
Dramatic plumes, both large and small, spray water ice particles and vapor along the famed “tiger stripes” near the south pole of Saturn’s moon Enceladus. Image via NASA/JPL/Space Science Institute.
2. Some are big, some are small (and big ones tend to fall)
Dust grains come in a range of sizes, which affects their properties. Particles can be extremely tiny, from only a few tens of nanometers (mere billionths of a meter) wide, to nearly a millimeter wide. As you might expect, smaller dust grains are more easily lifted and pushed around, be it by winds or magnetic, electrical and gravitational forces. Even the gentle pressure of sunlight is enough to move smaller dust particles in space. Bigger particles tend to be heavier, and they settle out more easily under the influence of gravity.
For example, on Earth, powerful winds can whip up large amounts of dust into the atmosphere. While the smaller grains can be transported over great distances, the heavier particles generally sink back to the ground near their source. On Saturn’s moon Enceladus, jets of icy dust particles spray hundreds of miles up from the surface; the bigger particles are lofted only a few tens of miles (or kilometers) and fall back to the ground, while the finest particles escape the moon’s gravity and go into orbit around Saturn to create the planet’s E ring.
Dust in the spiral galaxy M74 appears red in this image from NASA’s Spitzer Space Telescope. Data from Spitzer provided evidence that supernovae – the explosive deaths of massive stars – act as “dust factories,” seeding galaxies with cosmic dust particles. Image via NASA/JPL-Caltech/STScI.
3. It’s EVERYWHERE
Generally speaking, the space between the planets is pretty empty, but not completely so. Particles cast off by comets and ground up bits of asteroids are found throughout the solar system. Take any volume of space half a mile (1 kilometer) on a side, and you’d average a few micron-sized particles (grains the thickness of a red blood cell).
Dust in the solar system was a lot more abundant in the past. There was a huge amount of it present as the planets began to coalesce out of the disk of material that formed the sun. In fact, motes of dust gently sticking together were likely some of the earliest seeds of the planet-building process. But where did all that dust come from, originally? Some of it comes from stars like our sun, which blow off their outer layers in their later years. But lots of it also comes from exploding stars, which blast huge amounts of dust and gas into space when they go boom.
This mosaic of images from NASA’s Galileo spacecraft shows Jupiter’s ring system, which was only discovered after spacecraft had flown past the planet and could see the rings backlit by the sun. Image via NASA/JPL-Caltech/Cornell University.
4. From a certain point of view
Dust is easier to see from certain viewing angles. Tiny particles scatter light depending on how big their grains are. Larger particles tend to scatter light back in the direction from which it came, while very tiny particles tend to scatter light forward, more or less in the direction it was already going. Because of this property, structures like planetary rings made of the finest dusty particles are best viewed with the sun illuminating them from behind. For example, Jupiter’s rings were only discovered after the Voyager 1 spacecraft passed by the planet, where it could look back and see them backlit by the sun. You can see the same effect looking through a dusty windshield at sunset; when you face toward the sun, the dust becomes much more apparent.
Side-by-side movies show how dust enveloped the red planet in 2018, courtesy of NASA’s Mars Reconnaissance Orbiter. Image via NASA/JPL-Caltech/MSSS.
5. Dust storms are common on Mars
Local dust storms occur frequently on Mars, and occasionally grow or merge to form regional systems, particularly during the southern spring and summer, when Mars is closest to the Sun. On rare occasions, regional storms produce a dust haze that encircles the planet and obscures surface features beneath. A few of these events may become truly global storms, such as one in 1971 that greeted the first spacecraft to orbit Mars, NASA’s Mariner 9. In mid-2018, a global dust storm enshrouded Mars, hiding much of the Red Planet’s surface from view and threatening the continued operation of NASA’s uber long-lived Opportunity rover. We’ve also seen global dust storms in 1977, 1982, 1994, 2001 and 2007.
Dust storms will likely present challenges for future astronauts on the Red Planet. Although the force of the wind on Mars is not as strong as portrayed in an early scene in the movie The Martian, dust lofted during storms could affect electronics and health, as well as the availability of solar energy.
Sarharan dust is carried by winds to South America, where it helps fertilize the Amazon. Via NASA’s Goddard Space Flight Center.
6. Dust from the Sahara goes global
Earth’s largest, hottest desert is connected to its largest tropical rain forest by dust. The Sahara Desert is a near-uninterrupted brown band of sand and scrub across the northern third of Africa. The Amazon rain forest is a dense green mass of humid jungle that covers northeast South America. But after strong winds sweep across the Sahara, a dusty cloud rises in the air, stretches between the continents, and ties together the desert and the jungle.
This trans-continental journey of dust is important because of what is in the dust. Specifically, the dust picked up from the Bodélé Depression in Chad – an ancient lake bed where minerals composed of dead microorganisms are loaded with phosphorus. Phosphorus is an essential nutrient for plant proteins and growth, which the nutrient-poor Amazon rain forest depends on in order to flourish.
Saturn’s icy rings, backlit by the sun. The outer, bluish looking ring is composed entirely of icy dust particles sprayed into space by the moon Enceladus. Image via NASA/JPL-Caltech/SSI.
7. Rings and things
The rings of the giant planets contain a variety of different dusty materials. Jupiter’s rings are made of fine rock dust. Saturn’s rings are mostly pure water ice, with a sprinkling of other materials. (Side note about Saturn’s rings: While most of the particles are boulder-sized, there’s also lots of fine dust, and some of the fainter rings are mostly dust with few or no large particles.) Dust in the rings of Uranus and Neptune is made of dark, sooty material, probably rich in carbon.
Over time, dust gets removed from ring systems due to a variety of processes. For example, some of the dust falls into the planet’s atmosphere, while some gets swept up by the planets’ magnetic fields, and other dust settles onto the surfaces of the moons and other ring particles. Larger particles eventually form new moons or get ground down and mixed with incoming material. This means rings can change a lot over time, so understanding how the tiniest ring particles are being moved about has bearing on the history, origins and future of the rings.
Dark moon dust clings to the spacesuit of Apollo 17 astronaut Gene Cernan following an excursion on the lunar surface. Image via NASA.
8. Moon dust is clingy and might make you sick
So, dust is kind of a thing on the moon. When the Apollo astronauts visited the Moon, they found that lunar dust quickly coated their spacesuits and was difficult to remove. It was quite abrasive, causing wear on their spacesuit fabrics, seals and faceplates. It also clogged mechanisms like the joints in spacesuit limbs, and interfered with fasteners like zippers and Velcro. The astronauts also noted that it had a distinctive, pungent odor, not unlike gunpowder, and it was an eye and lung irritant.
Many of these properties apparently can be explained by the fact that lunar dust particles are quite rough and jagged. While dust particles on Earth get tumbled and ground by the wind into smoother shapes, this sort of weathering doesn’t happen so much on the moon. The roughness of moon dust grains makes it very easy for them to cling to surfaces and scratch them up. It also means they’re not the sort of thing you would want to inhale, as their jagged edges could damage delicate tissues in the lung.
Hubble Space Telescope image of comet ISON, taken in 2013. Image via NASA, ESA, and the Hubble Heritage Team (STScI/AURA).
9. Dust is what makes comets so pretty
Most comets are basically clods of dust, rock and ice. They spend most of their time far from the sun, out in the refrigerated depths of the outer solar system, where they’re peacefully dormant. But when their orbits carry them closer to the sun – that is, roughly inside the orbit of Jupiter – comets wake up. In response to warming temperatures, the ices on and near their surfaces begin to turn into gases, expanding outward and away from the comet, and creating focused jets of material in places. Dust gets carried away by this rapidly expanding gas, creating a fuzzy cloud around the comet’s nucleus called a coma. Some of the dust also is drawn out into a long trail – the comet’s tail.
Dust in our solar system is continually replenished by comets whizzing past the sun and the occasional asteroid collision, and it’s always being moved about, thanks to a variety of factors like the gravity of the planets and even the pressure of sunlight. Some of it even gets ejected from our solar system altogether.
With telescopes, we also observe dusty debris disks around many other stars. As in our own system, the dust in such disks should evolve over time, settling on planetary surfaces or being ejected, and this means the dust must be replenished in those star systems as well. So studying the dust in our planetary environs can tell us about other systems, and vice versa. Grains of dust from other planetary systems also pass through our neighborhood – a few spacecraft have actually captured and analyzed some them – offering us a tangible way to study material from other stars.
Bottom line: Ten facts about dust in space and on Earth.
Around early August, if you’re up early and have an unobstructed view to the east, be sure to look in that direction in the hour before dawn. You might find a familiar figure – a constellation that always returns to the sky around this time of year. It’s the beautiful constellation Orion the Hunter – recently behind the sun as seen from our earthly vantage point – now ascending once more in the east before sunrise.
The Hunter appears each northern winter as a mighty constellation arcing across the south during the evening hours. Many people see it then, and notice it, because the pattern of Orion’s stars is so distinctive.
But, at the crack of dawn in late summer, you can spot Orion in the east. Thus Orion has been called the ghost of the shimmering summer dawn.
The Hunter rises on his side, with his three Belt stars – Mintaka, Alnitak and Alnilam – pointing straight up.
The constellation Orion as viewed at morning dawn in early August. Image via Flickr user Micheal C. Rael
Also, notice the star Aldebaran in the constellation Taurus the Bull. Aldebaran is the brightest star in Taurus the Bull. It’s said to be the Bull’s fiery red eye. See the V-shaped pattern of stars around Aldebaran? This pattern represents the Bull’s face. In skylore, Orion is said to be holding up a great shield . . . fending off the charging Bull. Can you imagine this by looking at the chart at top? It’s easy to imagine when you look at the real sky before dawn at this time of year.
Bottom line: The return of Orion and Taurus to your predawn sky happens around late July or early August every year. In the Northern Hemisphere, Orion is sometimes called the ghost of the summer dawn.
Around early August, if you’re up early and have an unobstructed view to the east, be sure to look in that direction in the hour before dawn. You might find a familiar figure – a constellation that always returns to the sky around this time of year. It’s the beautiful constellation Orion the Hunter – recently behind the sun as seen from our earthly vantage point – now ascending once more in the east before sunrise.
The Hunter appears each northern winter as a mighty constellation arcing across the south during the evening hours. Many people see it then, and notice it, because the pattern of Orion’s stars is so distinctive.
But, at the crack of dawn in late summer, you can spot Orion in the east. Thus Orion has been called the ghost of the shimmering summer dawn.
The Hunter rises on his side, with his three Belt stars – Mintaka, Alnitak and Alnilam – pointing straight up.
The constellation Orion as viewed at morning dawn in early August. Image via Flickr user Micheal C. Rael
Also, notice the star Aldebaran in the constellation Taurus the Bull. Aldebaran is the brightest star in Taurus the Bull. It’s said to be the Bull’s fiery red eye. See the V-shaped pattern of stars around Aldebaran? This pattern represents the Bull’s face. In skylore, Orion is said to be holding up a great shield . . . fending off the charging Bull. Can you imagine this by looking at the chart at top? It’s easy to imagine when you look at the real sky before dawn at this time of year.
Bottom line: The return of Orion and Taurus to your predawn sky happens around late July or early August every year. In the Northern Hemisphere, Orion is sometimes called the ghost of the summer dawn.
Brain tumours are hard to treat and survival remains stubbornly low. That’s why brain tumour research is one of our top priorities. In the second of a 3-part series, Parminder shares her treatment journey.
When I was first told I had a brain tumour I laughed. I just didn’t believe it. My dad was in the room and he told me to stop laughing and to take the doctor seriously. I couldn’t, I thought it just wasn’t possible.
I was 28 at the time and I used to wake up every day with a terrible headache, bizarre déjà vu and a weird metallic taste in my mouth. This happened for a few weeks. I thought it was something to do with my tooth fillings so I went to the dentist who recommended getting my wisdom teeth x-rayed.
So, I went to get an x-ray and I honestly don’t know what came over me, but I lied to the technician. I told her that I’d been getting headaches and that today it was so bad, I’d passed out and hit my head on the coffee table. It was a complete lie, but I just needed someone to understand me. She fetched a doctor and he was really good and listened to me, and arranged a CT scan for me the following morning.
My parents came with me and that’s when we were told: “I’m afraid it’s not good news.”
Why me?
At first I was in complete shock. And then I was angry and thought, ‘why me?’
After the doctors explained everything they moved very quickly. They didn’t know if what I had growing in my head was cancerous, but they knew it was a brain tumour and that they had to get it out as soon as possible.
The surgery lasted 8 hours, the longest 8 hours of my parents’ life.
I was shifted to Charing Cross Hospital where I was put on steroids and anti-seizure medication. It turned out that the funny metal taste in my mouth was a symptom of seizures I’d been having, which also gave me déjà vu.
The steroids made me so hungry. My mum was having to go to the supermarket every other day for me, I couldn’t stop eating! I had surgery a few weeks later. It lasted 8 hours, the longest 8 hours of my parents’ life. They removed 70% of the tumour and sent it off to be analysed. I was in hospital for 10 days and felt down that I was stuck in there.
It was about 2 weeks before I received the letter telling me come to back to hospital to discuss my results. As soon as I saw the word ‘oncology’ on the letter I knew it was cancer. They told me I had a grade 3 astrocytoma. It had been growing in my head for a whole year.
Milkshakes and hot dogs
It was the end of 2011 when I was diagnosed. But because it was Christmas, I was told that I’d start further treatment in the new year. I needed 6 weeks of radiotherapy and chemotherapy and couldn’t have any breaks.
The chemotherapy was the hardest treatment. I had to take anti-sickness drugs followed by 5 tablets of temozolomide every morning on an empty stomach. I was told that they’re very toxic and not to touch them, so I had to pop them into the lid of the bottle and then in my mouth.
I just used to close my eyes and try to imagine that I was on a tropical island.
The first time I took the chemotherapy I felt fine. I got home and was starving so I made burritos and shovelled at least 2 or 3 down! I couldn’t understand why people complained about sickness. But I spoke too soon. 20 minutes later I was throwing everything back up. The anti-sickness drugs did eventually work but they’re not the best; I still felt nauseous the entire time.
I also had a bad allergic reaction to the temozolomide. My face was covered in a rash and I was rushed into hospital where they gave me antihistamines on a drip, which quickly got it under control. The chemotherapy makes you want to sleep all the time. I also couldn’t really eat much, I couldn’t stand the sight of food. Milkshakes and hot dogs were pretty much the only thing I could stomach.
The radiotherapy I had alongside my chemotherapy was at Charing Cross Hospital. I had to have a mask that was made specially for me. It would take anywhere between half an hour and an hour and 40 minutes. It wasn’t that bad at all. I just used to close my eyes and try to imagine that I was on a tropical island. It didn’t affect my hair too much except for on my right side where the beam went in, where I don’t have any hair. But I hide that well.
An unexpected effect
After the 6 weeks of treatment I had another scan, and they saw that there was still some of the tumour left. So, I had another 3 months of chemotherapy, but this time it was 1 week on 3 weeks off. I had another scan and my doctor said there was no evidence of disease. I jumped for joy and nearly knocked the poor woman off her chair!
After that I had a scan every 3 months, which went down to every 6 months and then once a year.
During check-ups I was shocked to find out that the steroids had affected my right hip. I have something called avascular necrosis, where there’s no good supply of blood to the hip bone. It repairs itself but it gets weak, and last year I was told that because I’m so active, I’ve got about 5 years before I might need a hip replacement. It also means that I can’t have a natural birth if I was to have a child, I’d need a C-section.
That was all a total surprise for me. I knew all about the hunger and the bloated face from the steroids, but no one told me that this could be a side effect.
Déjà vu, again
It was 2012 when I got the all clear. But, unfortunately, at the beginning of this year I started getting headaches, déjà vu and the funny taste again. So, I had another scan, which showed that it had come back.
I never usually cry but I burst into tears. Then I pulled myself together and asked, “how are we going to fix it this time then?” I was straight in for surgery. They told me that because it was caught early and it was safe to do so, this time the surgeon could remove all of the tumour.
I’m not the kind of person who sits around feeling sorry for myself.
The second time the surgery was much harder for me, but I was still back in work after about 2 weeks. I’m not the kind of person who sits around feeling sorry for myself. But the doctors found 2 more little spots of brain tumour that they can’t get to through surgery, so I need another round of chemotherapy.
I’m still going to carry on working but the weeks I have the chemotherapy I’m going to work from home, so I can have a sleep when I need to. My work has been so understanding, and my colleagues all think I’m Superwoman to come back into work so quickly!
Life’s too short
Parminder had temozolomide for her brain tumour – a drug our scientists developed.
The main thing that’s helped me through everything is the support of my family and friends. It’s something to live for, and keeps me going. I need to fight this for their sake.
Having been sick the first time and now having to go through it again, I’ve realised that life is way too short and you should just have fun. I’ve got a bucket list; I want to go on safari in Africa, shark diving in Cape Town and see the northern lights. I’ve beaten it once, so I’m going to do it again.
There’s no way I’m going to let the cancer win. I’ve got too much to do.
If you’ve been affected by cancer and would like to speak to someone, you can call our nurses on freephone 0808 800 4040, 9am until 5pm Monday to Friday. Alternatively, you can join our friendly and supportive discussion forum, Cancer Chat.
from Cancer Research UK – Science blog https://ift.tt/2Kgd6o6
Brain tumours are hard to treat and survival remains stubbornly low. That’s why brain tumour research is one of our top priorities. In the second of a 3-part series, Parminder shares her treatment journey.
When I was first told I had a brain tumour I laughed. I just didn’t believe it. My dad was in the room and he told me to stop laughing and to take the doctor seriously. I couldn’t, I thought it just wasn’t possible.
I was 28 at the time and I used to wake up every day with a terrible headache, bizarre déjà vu and a weird metallic taste in my mouth. This happened for a few weeks. I thought it was something to do with my tooth fillings so I went to the dentist who recommended getting my wisdom teeth x-rayed.
So, I went to get an x-ray and I honestly don’t know what came over me, but I lied to the technician. I told her that I’d been getting headaches and that today it was so bad, I’d passed out and hit my head on the coffee table. It was a complete lie, but I just needed someone to understand me. She fetched a doctor and he was really good and listened to me, and arranged a CT scan for me the following morning.
My parents came with me and that’s when we were told: “I’m afraid it’s not good news.”
Why me?
At first I was in complete shock. And then I was angry and thought, ‘why me?’
After the doctors explained everything they moved very quickly. They didn’t know if what I had growing in my head was cancerous, but they knew it was a brain tumour and that they had to get it out as soon as possible.
The surgery lasted 8 hours, the longest 8 hours of my parents’ life.
I was shifted to Charing Cross Hospital where I was put on steroids and anti-seizure medication. It turned out that the funny metal taste in my mouth was a symptom of seizures I’d been having, which also gave me déjà vu.
The steroids made me so hungry. My mum was having to go to the supermarket every other day for me, I couldn’t stop eating! I had surgery a few weeks later. It lasted 8 hours, the longest 8 hours of my parents’ life. They removed 70% of the tumour and sent it off to be analysed. I was in hospital for 10 days and felt down that I was stuck in there.
It was about 2 weeks before I received the letter telling me come to back to hospital to discuss my results. As soon as I saw the word ‘oncology’ on the letter I knew it was cancer. They told me I had a grade 3 astrocytoma. It had been growing in my head for a whole year.
Milkshakes and hot dogs
It was the end of 2011 when I was diagnosed. But because it was Christmas, I was told that I’d start further treatment in the new year. I needed 6 weeks of radiotherapy and chemotherapy and couldn’t have any breaks.
The chemotherapy was the hardest treatment. I had to take anti-sickness drugs followed by 5 tablets of temozolomide every morning on an empty stomach. I was told that they’re very toxic and not to touch them, so I had to pop them into the lid of the bottle and then in my mouth.
I just used to close my eyes and try to imagine that I was on a tropical island.
The first time I took the chemotherapy I felt fine. I got home and was starving so I made burritos and shovelled at least 2 or 3 down! I couldn’t understand why people complained about sickness. But I spoke too soon. 20 minutes later I was throwing everything back up. The anti-sickness drugs did eventually work but they’re not the best; I still felt nauseous the entire time.
I also had a bad allergic reaction to the temozolomide. My face was covered in a rash and I was rushed into hospital where they gave me antihistamines on a drip, which quickly got it under control. The chemotherapy makes you want to sleep all the time. I also couldn’t really eat much, I couldn’t stand the sight of food. Milkshakes and hot dogs were pretty much the only thing I could stomach.
The radiotherapy I had alongside my chemotherapy was at Charing Cross Hospital. I had to have a mask that was made specially for me. It would take anywhere between half an hour and an hour and 40 minutes. It wasn’t that bad at all. I just used to close my eyes and try to imagine that I was on a tropical island. It didn’t affect my hair too much except for on my right side where the beam went in, where I don’t have any hair. But I hide that well.
An unexpected effect
After the 6 weeks of treatment I had another scan, and they saw that there was still some of the tumour left. So, I had another 3 months of chemotherapy, but this time it was 1 week on 3 weeks off. I had another scan and my doctor said there was no evidence of disease. I jumped for joy and nearly knocked the poor woman off her chair!
After that I had a scan every 3 months, which went down to every 6 months and then once a year.
During check-ups I was shocked to find out that the steroids had affected my right hip. I have something called avascular necrosis, where there’s no good supply of blood to the hip bone. It repairs itself but it gets weak, and last year I was told that because I’m so active, I’ve got about 5 years before I might need a hip replacement. It also means that I can’t have a natural birth if I was to have a child, I’d need a C-section.
That was all a total surprise for me. I knew all about the hunger and the bloated face from the steroids, but no one told me that this could be a side effect.
Déjà vu, again
It was 2012 when I got the all clear. But, unfortunately, at the beginning of this year I started getting headaches, déjà vu and the funny taste again. So, I had another scan, which showed that it had come back.
I never usually cry but I burst into tears. Then I pulled myself together and asked, “how are we going to fix it this time then?” I was straight in for surgery. They told me that because it was caught early and it was safe to do so, this time the surgeon could remove all of the tumour.
I’m not the kind of person who sits around feeling sorry for myself.
The second time the surgery was much harder for me, but I was still back in work after about 2 weeks. I’m not the kind of person who sits around feeling sorry for myself. But the doctors found 2 more little spots of brain tumour that they can’t get to through surgery, so I need another round of chemotherapy.
I’m still going to carry on working but the weeks I have the chemotherapy I’m going to work from home, so I can have a sleep when I need to. My work has been so understanding, and my colleagues all think I’m Superwoman to come back into work so quickly!
Life’s too short
Parminder had temozolomide for her brain tumour – a drug our scientists developed.
The main thing that’s helped me through everything is the support of my family and friends. It’s something to live for, and keeps me going. I need to fight this for their sake.
Having been sick the first time and now having to go through it again, I’ve realised that life is way too short and you should just have fun. I’ve got a bucket list; I want to go on safari in Africa, shark diving in Cape Town and see the northern lights. I’ve beaten it once, so I’m going to do it again.
There’s no way I’m going to let the cancer win. I’ve got too much to do.
If you’ve been affected by cancer and would like to speak to someone, you can call our nurses on freephone 0808 800 4040, 9am until 5pm Monday to Friday. Alternatively, you can join our friendly and supportive discussion forum, Cancer Chat.
from Cancer Research UK – Science blog https://ift.tt/2Kgd6o6
You can catch Venus and Jupiter – 2 very bright planets – in the western half of sky at nightfall throughout August, 2018. Be sure to catch ’em around mid-August, when the moon sweeps near. Read more.
Click the name of a planet to learn more about its visibility in July 2018: Venus, Jupiter, Saturn, Mars and Mercury
Venus is the brightest planet, and it’s very prominent this month in the west after sunset. Throughout August, Venus appears as a dazzling evening “star.” Look for Venus to adorn the western evening sky until October 2018.
At mid-northern latitudes, Venus attained its highest altitude as the evening “star” in June 2018. That’s in spite of the fact that Venus’ greatest elongation (maximum angular distance from the setting sun) won’t occur until August 17, 2018. At mid-northern latitudes, Venus sets roughly 2 hours after the sun in early August. By the month’s end, that’ll taper to about 1 1/2 hours after sunset.
In the Southern Hemisphere, Venus climbs highest up in the evening sky in August. At temperate latitudes in the Southern Hemisphere (South Africa, southern Australia), Venus sets about 3 1/2 hours after sunset throughout the month.
Circle August 14, 15 and 16 on your calendar. That’s when the young moon will be sweeping past Venus (and Jupiter) in the evening sky. The western twilight will make the pairing all the more picturesque.
In 2018, Jupiter acts as your guide to the constellation Libra. Raul Cortes in Monterrey, Mexico, created this image from a photo he took on June 4, 2018.
Jupiter remains bright and beautiful throughout August 2018. Our planet Earth passed between the sun and Jupiter – bringing the planet to opposition – on the night of May 8-9, 2018. In the Northern Hemisphere, you’ll find Jupiter highest up for the night around dusk or nightfall, appearing a bit west (right) of due south; in the Southern Hemisphere, you’ll see Jupiter nearly overhead at dusk. Jupiter is brighter than any star, but it’s not brighter than Venus, which beams mightily in the west after sunset.
Although Jupiter is usually the 4th-brightest celestial object to light up the heavens, after the sun, moon and Venus, Mars actually supersedes Jupiter as the 4th-brightest celestial object all month long in August 2018.
Jupiter shines in front of the constellation Libra the Scales until November 2018. Look for Libra’s brightest stars near Jupiter, Zubenelgenubi and Zubeneschamali (both star names are pronounced with the same rhythm as Obi-Wan Kenobi, of “Star Wars”).
If you aim binoculars at Zubenelgenubi, you’ll see this star as two stars. Zubeneschamali, meanwhile, is said to appear green in color, although, astronomers say, stars can’t look green.
Let the moon guide your eye to Jupiter on the evenings of August 16 and August 17.
On August 17, 2018, the moon shines close to Jupiter, on the same date that Venus reaches its greatest elongation. Read more.
Saturn and Mars adorn the eastern half of the sky at dusk and nightfall. During the first few weeks of August, Saturn transits – reaches its high point for the night – at about the same time that Venus sets (roughly 9 p.m. local time or 10 p.m. local daylight saving time). Then Mars transits some two hours after Saturn does.
Near the month’s end, Saturn will transit at roughly 8 p.m. local time (9 p.m. local daylight saving time), and throughout the month, Mars will transit about two hours after Saturn does.
Middle to late evening offers a better view of Saturn and Mars, as these worlds are seen higher up in the sky than they are at nightfall.
You can tell Mars from Saturn because Mars has a reddish color and Saturn looks golden. Binoculars show their colors better than the eye alone.
Watch for the moon to pair up with Saturn on or near August 20 and with Mars on or near August 23.
Watch for the moon to go by Saturn and journey toward Mars from August 20 to 22. Read more.
At present, both Saturn and Mars shine more brilliantly than a 1st-magnitude star. However, Mars is brighter than Saturn. Saturn’s brilliance peaked at its June 27 opposition, and Mars’ brilliance came to a head at its July 27 opposition.
It’s not often that Mars outshines Jupiter, normally the fourth-brightest celestial object to light up the sky, after the sun, moon and Venus. But, for a couple of months in 2018, Mars will outshine Jupiter from about July 7 to September 7, 2018.
Both Mars and Saturn are slowly dimming throughout the month. Because Mars is dimming at a faster rate than Saturn is, Mars will be about 15 times brighter than Saturn at the beginning of the month, and some 10 times brighter by the month’s end.
Remember Mars’ historically close opposition of August 28, 2003? That year, it was closer and brighter than it had been in some 60,000 years. The July opposition was the best since 2003, and what’s more, Mars will remain bright and beautiful all through August 2018!
Diagram by Roy L. Bishop. Copyright Royal Astronomical Society of Canada. Used with permission. Visit the RASC estore to purchase the Observer’s Handbook, a necessary tool for all skywatchers. Read more about this image.
Mercury, the innermost planet of the solar system, moves out of the evening sky and into the morning sky on August 9, 2018. Mercury probably won’t first become visible in the morning sky until August 20th or so. The last week of August and the first several days of September will provide a good view of Mercury for the Northern Hemisphere and the southern tropics. Mercury will be harder to spot from temperate latitudes in the Southern Hemisphere.
During the last week of August at mid-northern latitudes, Mercury will rise about 1 1/2 hours before sunrise. At temperate latitudes in the Southern Hemisphere, on the other hand, Mercury only rises an hour or less before the sun. Click here for a recommended almanac telling you when the sun and Mercury rise into your sky.
Familiar with the Winter Circle? It’ll help you to locate Mercury, the innermost planet, in the morning sky. Read more.
What do we mean by bright planet? By bright planet, we mean any solar system planet that is easily visible without an optical aid and that has been watched by our ancestors since time immemorial. In their outward order from the sun, the five bright planets are Mercury, Venus, Mars, Jupiter and Saturn. These planets actually do appear bright in our sky. They are typically as bright as – or brighter than – the brightest stars. Plus, these relatively nearby worlds tend to shine with a steadier light than the distant, twinkling stars. You can spot them, and come to know them as faithful friends, if you try.
Bottom line: In August 2018, four planets arc across the sky at dusk and nightfall. Venus lights up the western sky, with Jupiter shining above Venus, whereas Mars lords the southeast sky, with Saturn shining above Mars. Mercury becomes a morning “star” by the last week of August. Click here for recommended almanacs; they can help you know when the planets rise, transit and set in your sky.
You can catch Venus and Jupiter – 2 very bright planets – in the western half of sky at nightfall throughout August, 2018. Be sure to catch ’em around mid-August, when the moon sweeps near. Read more.
Click the name of a planet to learn more about its visibility in July 2018: Venus, Jupiter, Saturn, Mars and Mercury
Venus is the brightest planet, and it’s very prominent this month in the west after sunset. Throughout August, Venus appears as a dazzling evening “star.” Look for Venus to adorn the western evening sky until October 2018.
At mid-northern latitudes, Venus attained its highest altitude as the evening “star” in June 2018. That’s in spite of the fact that Venus’ greatest elongation (maximum angular distance from the setting sun) won’t occur until August 17, 2018. At mid-northern latitudes, Venus sets roughly 2 hours after the sun in early August. By the month’s end, that’ll taper to about 1 1/2 hours after sunset.
In the Southern Hemisphere, Venus climbs highest up in the evening sky in August. At temperate latitudes in the Southern Hemisphere (South Africa, southern Australia), Venus sets about 3 1/2 hours after sunset throughout the month.
Circle August 14, 15 and 16 on your calendar. That’s when the young moon will be sweeping past Venus (and Jupiter) in the evening sky. The western twilight will make the pairing all the more picturesque.
In 2018, Jupiter acts as your guide to the constellation Libra. Raul Cortes in Monterrey, Mexico, created this image from a photo he took on June 4, 2018.
Jupiter remains bright and beautiful throughout August 2018. Our planet Earth passed between the sun and Jupiter – bringing the planet to opposition – on the night of May 8-9, 2018. In the Northern Hemisphere, you’ll find Jupiter highest up for the night around dusk or nightfall, appearing a bit west (right) of due south; in the Southern Hemisphere, you’ll see Jupiter nearly overhead at dusk. Jupiter is brighter than any star, but it’s not brighter than Venus, which beams mightily in the west after sunset.
Although Jupiter is usually the 4th-brightest celestial object to light up the heavens, after the sun, moon and Venus, Mars actually supersedes Jupiter as the 4th-brightest celestial object all month long in August 2018.
Jupiter shines in front of the constellation Libra the Scales until November 2018. Look for Libra’s brightest stars near Jupiter, Zubenelgenubi and Zubeneschamali (both star names are pronounced with the same rhythm as Obi-Wan Kenobi, of “Star Wars”).
If you aim binoculars at Zubenelgenubi, you’ll see this star as two stars. Zubeneschamali, meanwhile, is said to appear green in color, although, astronomers say, stars can’t look green.
Let the moon guide your eye to Jupiter on the evenings of August 16 and August 17.
On August 17, 2018, the moon shines close to Jupiter, on the same date that Venus reaches its greatest elongation. Read more.
Saturn and Mars adorn the eastern half of the sky at dusk and nightfall. During the first few weeks of August, Saturn transits – reaches its high point for the night – at about the same time that Venus sets (roughly 9 p.m. local time or 10 p.m. local daylight saving time). Then Mars transits some two hours after Saturn does.
Near the month’s end, Saturn will transit at roughly 8 p.m. local time (9 p.m. local daylight saving time), and throughout the month, Mars will transit about two hours after Saturn does.
Middle to late evening offers a better view of Saturn and Mars, as these worlds are seen higher up in the sky than they are at nightfall.
You can tell Mars from Saturn because Mars has a reddish color and Saturn looks golden. Binoculars show their colors better than the eye alone.
Watch for the moon to pair up with Saturn on or near August 20 and with Mars on or near August 23.
Watch for the moon to go by Saturn and journey toward Mars from August 20 to 22. Read more.
At present, both Saturn and Mars shine more brilliantly than a 1st-magnitude star. However, Mars is brighter than Saturn. Saturn’s brilliance peaked at its June 27 opposition, and Mars’ brilliance came to a head at its July 27 opposition.
It’s not often that Mars outshines Jupiter, normally the fourth-brightest celestial object to light up the sky, after the sun, moon and Venus. But, for a couple of months in 2018, Mars will outshine Jupiter from about July 7 to September 7, 2018.
Both Mars and Saturn are slowly dimming throughout the month. Because Mars is dimming at a faster rate than Saturn is, Mars will be about 15 times brighter than Saturn at the beginning of the month, and some 10 times brighter by the month’s end.
Remember Mars’ historically close opposition of August 28, 2003? That year, it was closer and brighter than it had been in some 60,000 years. The July opposition was the best since 2003, and what’s more, Mars will remain bright and beautiful all through August 2018!
Diagram by Roy L. Bishop. Copyright Royal Astronomical Society of Canada. Used with permission. Visit the RASC estore to purchase the Observer’s Handbook, a necessary tool for all skywatchers. Read more about this image.
Mercury, the innermost planet of the solar system, moves out of the evening sky and into the morning sky on August 9, 2018. Mercury probably won’t first become visible in the morning sky until August 20th or so. The last week of August and the first several days of September will provide a good view of Mercury for the Northern Hemisphere and the southern tropics. Mercury will be harder to spot from temperate latitudes in the Southern Hemisphere.
During the last week of August at mid-northern latitudes, Mercury will rise about 1 1/2 hours before sunrise. At temperate latitudes in the Southern Hemisphere, on the other hand, Mercury only rises an hour or less before the sun. Click here for a recommended almanac telling you when the sun and Mercury rise into your sky.
Familiar with the Winter Circle? It’ll help you to locate Mercury, the innermost planet, in the morning sky. Read more.
What do we mean by bright planet? By bright planet, we mean any solar system planet that is easily visible without an optical aid and that has been watched by our ancestors since time immemorial. In their outward order from the sun, the five bright planets are Mercury, Venus, Mars, Jupiter and Saturn. These planets actually do appear bright in our sky. They are typically as bright as – or brighter than – the brightest stars. Plus, these relatively nearby worlds tend to shine with a steadier light than the distant, twinkling stars. You can spot them, and come to know them as faithful friends, if you try.
Bottom line: In August 2018, four planets arc across the sky at dusk and nightfall. Venus lights up the western sky, with Jupiter shining above Venus, whereas Mars lords the southeast sky, with Saturn shining above Mars. Mercury becomes a morning “star” by the last week of August. Click here for recommended almanacs; they can help you know when the planets rise, transit and set in your sky.
View full video. | This NASA animation depicts a mapping of the positions of known near-Earth objects (NEOs) at points in time over the past 20 years. It finishes with a map of all known asteroids as of January 2018. There are now over 18,000 known NEOs and the discovery rate averages about 40 per week. Image via NASA/JPL-Caltech.
On March 11, 1998, asteroid astronomers around the world received an ominous message: new observational data on the recently discovered asteroid 1997 XF11 suggested there was a chance that the half-mile-wide (nearly one km wide) object could hit Earth in 2028.
The message came from the Minor Planet Center, in Cambridge, Massachusetts, the worldwide repository for such observations and initial determination of asteroid orbits. And although it was intended to alert only the very small astronomical community that hunts and tracks asteroids to call for more observations, the news spread quickly.
Most media outlets did not know what to make of the announcement, and mistakenly highlighted the prospect that Earth was doomed.
Fortunately, it turned out that Earth was never in danger from 1997 XF11. After performing a more thorough orbit analysis with the available asteroid observations, Don Yeomans, then the leader of the Solar System Dynamics group at NASA’s Jet Propulsion Laboratory in Pasadena, California, along with his colleague Paul Chodas, concluded otherwise. Chodas, who is now director of NASA’s Center for Near-Earth Object Studies (CNEOS), located at JPL, said:
The 2028 impact was essentially impossible.
To this day we still get queries on the chances of XF11 impacting in 2028. There is simply no chance of XF11 impacting our planet that year, or for the next 200 years.
Chodas knows this thanks to CNEOS’ precise orbit calculations using observation data submitted to the Minor Planet Center by observatories all over the world that detect and track the motion of asteroids and comets. For the past two decades, CNEOS calculations have enabled NASA to become the world leader in these efforts, keeping close watch on all nearby asteroids and comets — especially those that can cross Earth’s orbit. Chodas said:
We compute high-precision orbits for all asteroids and comets and map their positions in the solar system, both forward in time to detect potential impacts, and backward to see where they’ve been in the sky. We provide the best map of orbits for all known small bodies in the solar system.
The chart depicts the cumulative number of known Near-Earth asteroids (NEAs) versus time. The area in red depicts the number of known NEAs larger than 0.6 miles (1 km). The area in orange depicts the quantity of known NEAs larger than 460 feet (140 meters). The area in blue depicts the number of known NEAs in all sizes. Image via NASA/JPL-Caltech.
Mapping the Celestial Hazard
Near-Earth Objects (NEOs) are asteroids and comets in orbits that bring them into the inner solar system, within 121 million miles (195 million km) of the sun, and also within roughly 30 million miles (50 million km) of Earth’s orbit around the sun.
The media frenzy around NEO 1997 XF11 demonstrated the need for clarity and precision in communicating with the public about the close passes by Earth of these objects, as well as, Chodas said:
… the importance of peer review before public statements like these are made.
NASA’s original intent was to fulfill a 1998 Congressional request to detect and catalog at least 90 percent of all NEOs larger than one kilometer in size (roughly two-thirds of a mile) within 10 years. To help reach the Congressional goal, NASA Headquarters requested that JPL establish a new office to work with the data provided by the International Astronomical Union-sanctioned Minor Planet Center for submission of all observations of asteroids and comets, and to coordinate with observatories operated by academic institutions around the United States, as well as U.S. Air Force space surveillance assets.
In the summer of 1998, NASA established the Near-Earth Object Observations Program, and JPL became the home for the agency’s research data and analysis on NEOs, then called the Near-Earth Object Program Office.
In 2016, the office was renamed the Center for Near-Earth Object Studies (CNEOS) in conjunction with the establishment of the Planetary Defense Coordination Office at NASA Headquarters in Washington.
For about 20 years, CNEOS has been NASA’s central hub for accurately mapping the orbits of all the known NEOs, predicting their upcoming close approaches, reliably assessing their chances of impact to our planet, and delivering that information to both astronomers worldwide and the general public.
Predicting Close Approaches and Impacts: Sentry and Scout
The first and most important step in assessing the impact risk of an asteroid or comet is to determine whether any given object’s orbit will cross Earth’s orbit — and then how close it will actually get to our planet. JPL was determining high-precision orbits for a few NEOs even before NASA launched its NEO Observations Program, and has since upgraded its orbit models to provide the most accurate assessment available for asteroid positions and orbits.
Observatories around the world take digital images of the sky to detect moving points of light (the asteroid or comet) over days, weeks, months and even decades. They then report the positions of these moving objects relative to the static background of stars to the Minor Planet Center (for more details, see How a Speck of Light Becomes an Asteroid). The CNEOS scientists then use all this observation data to more precisely calculate an NEO’s orbit and predict its motion forward in time for many years, looking for close approaches and potential impacts to the Earth, its moon, and other planets.
A CNEOS system called Sentry searches ahead for all potential future Earth impact possibilities over the next 100 years — for every known NEO. Sentry’s impact monitoring runs continually using the latest CNEOS-generated orbit models, and the results are stored online. In most cases so far, the probabilities of any potential impacts are extremely small, and in other cases, the objects themselves are so small — less than 20 meters in size, or nearly 66 feet — that they would almost certainly disintegrate even if they did enter Earth’s atmosphere. Steve Chesley of JPL, a member of the CNEOS team who was the main developer of the Sentry system, said:
If Sentry finds potential impacts for an object, we add it to our online ‘impact risk’ table, and asteroid observers can then prioritize that object for further observation. The more measurements made of the object’s position over time, the better we can predict its future path.
In most cases, the new measurements mean the object can be removed from the risk list because the uncertainties in the orbital path are reduced and the possibility of impact is ruled out.
More recently, CNEOS also developed a system called Scout to provide more immediate and automatic trajectory analyses for the most recently discovered objects, even before independent observatories confirm their discovery. Operating around the clock, the Scout system not only notifies observers of the highest priority objects to observe at any given time, it also immediately alerts the Planetary Defense Coordination Office of any possible imminent impacts within the next few hours or days.A recent example is the Scout-predicted impact of the small asteroid 2018 LA over Botswana, Africa.
More Hunting to Do
With the addition of more capable NASA-funded asteroid surveys over the years, NASA’s NEO Observations Program is responsible for over 90 percent of near-Earth asteroid and comet discoveries. There are now over 18,000 known NEOs and the discovery rate averages about 40 per week.
Although the original Congressional goal from 1998 has been exceeded and much progress has been made in asteroid discovery and tracking over the past two decades, the work isn’t over. In 2005, Congress established a new, much more ambitious goal for the NEO Observations Program — to discover 90 percent of the NEOs down to the much smaller size of 450 feet (140 meters), and to do so by the year 2020.
These smaller asteroids may not present a threat of global catastrophe if they impact Earth, but they could still cause massive regional devastation and loss of life, especially if they occur near a metropolitan area. CNEOS continues to make improvements to its orbital analysis tools, image and graphic presentation capabilities, and updates of its websites to quickly and accurately provide the very latest information on NEOs to PDCO, the astronomical community and the public.
More information about CNEOS, asteroids and near-Earth objects can be found at:
View full video. | This NASA animation depicts a mapping of the positions of known near-Earth objects (NEOs) at points in time over the past 20 years. It finishes with a map of all known asteroids as of January 2018. There are now over 18,000 known NEOs and the discovery rate averages about 40 per week. Image via NASA/JPL-Caltech.
On March 11, 1998, asteroid astronomers around the world received an ominous message: new observational data on the recently discovered asteroid 1997 XF11 suggested there was a chance that the half-mile-wide (nearly one km wide) object could hit Earth in 2028.
The message came from the Minor Planet Center, in Cambridge, Massachusetts, the worldwide repository for such observations and initial determination of asteroid orbits. And although it was intended to alert only the very small astronomical community that hunts and tracks asteroids to call for more observations, the news spread quickly.
Most media outlets did not know what to make of the announcement, and mistakenly highlighted the prospect that Earth was doomed.
Fortunately, it turned out that Earth was never in danger from 1997 XF11. After performing a more thorough orbit analysis with the available asteroid observations, Don Yeomans, then the leader of the Solar System Dynamics group at NASA’s Jet Propulsion Laboratory in Pasadena, California, along with his colleague Paul Chodas, concluded otherwise. Chodas, who is now director of NASA’s Center for Near-Earth Object Studies (CNEOS), located at JPL, said:
The 2028 impact was essentially impossible.
To this day we still get queries on the chances of XF11 impacting in 2028. There is simply no chance of XF11 impacting our planet that year, or for the next 200 years.
Chodas knows this thanks to CNEOS’ precise orbit calculations using observation data submitted to the Minor Planet Center by observatories all over the world that detect and track the motion of asteroids and comets. For the past two decades, CNEOS calculations have enabled NASA to become the world leader in these efforts, keeping close watch on all nearby asteroids and comets — especially those that can cross Earth’s orbit. Chodas said:
We compute high-precision orbits for all asteroids and comets and map their positions in the solar system, both forward in time to detect potential impacts, and backward to see where they’ve been in the sky. We provide the best map of orbits for all known small bodies in the solar system.
The chart depicts the cumulative number of known Near-Earth asteroids (NEAs) versus time. The area in red depicts the number of known NEAs larger than 0.6 miles (1 km). The area in orange depicts the quantity of known NEAs larger than 460 feet (140 meters). The area in blue depicts the number of known NEAs in all sizes. Image via NASA/JPL-Caltech.
Mapping the Celestial Hazard
Near-Earth Objects (NEOs) are asteroids and comets in orbits that bring them into the inner solar system, within 121 million miles (195 million km) of the sun, and also within roughly 30 million miles (50 million km) of Earth’s orbit around the sun.
The media frenzy around NEO 1997 XF11 demonstrated the need for clarity and precision in communicating with the public about the close passes by Earth of these objects, as well as, Chodas said:
… the importance of peer review before public statements like these are made.
NASA’s original intent was to fulfill a 1998 Congressional request to detect and catalog at least 90 percent of all NEOs larger than one kilometer in size (roughly two-thirds of a mile) within 10 years. To help reach the Congressional goal, NASA Headquarters requested that JPL establish a new office to work with the data provided by the International Astronomical Union-sanctioned Minor Planet Center for submission of all observations of asteroids and comets, and to coordinate with observatories operated by academic institutions around the United States, as well as U.S. Air Force space surveillance assets.
In the summer of 1998, NASA established the Near-Earth Object Observations Program, and JPL became the home for the agency’s research data and analysis on NEOs, then called the Near-Earth Object Program Office.
In 2016, the office was renamed the Center for Near-Earth Object Studies (CNEOS) in conjunction with the establishment of the Planetary Defense Coordination Office at NASA Headquarters in Washington.
For about 20 years, CNEOS has been NASA’s central hub for accurately mapping the orbits of all the known NEOs, predicting their upcoming close approaches, reliably assessing their chances of impact to our planet, and delivering that information to both astronomers worldwide and the general public.
Predicting Close Approaches and Impacts: Sentry and Scout
The first and most important step in assessing the impact risk of an asteroid or comet is to determine whether any given object’s orbit will cross Earth’s orbit — and then how close it will actually get to our planet. JPL was determining high-precision orbits for a few NEOs even before NASA launched its NEO Observations Program, and has since upgraded its orbit models to provide the most accurate assessment available for asteroid positions and orbits.
Observatories around the world take digital images of the sky to detect moving points of light (the asteroid or comet) over days, weeks, months and even decades. They then report the positions of these moving objects relative to the static background of stars to the Minor Planet Center (for more details, see How a Speck of Light Becomes an Asteroid). The CNEOS scientists then use all this observation data to more precisely calculate an NEO’s orbit and predict its motion forward in time for many years, looking for close approaches and potential impacts to the Earth, its moon, and other planets.
A CNEOS system called Sentry searches ahead for all potential future Earth impact possibilities over the next 100 years — for every known NEO. Sentry’s impact monitoring runs continually using the latest CNEOS-generated orbit models, and the results are stored online. In most cases so far, the probabilities of any potential impacts are extremely small, and in other cases, the objects themselves are so small — less than 20 meters in size, or nearly 66 feet — that they would almost certainly disintegrate even if they did enter Earth’s atmosphere. Steve Chesley of JPL, a member of the CNEOS team who was the main developer of the Sentry system, said:
If Sentry finds potential impacts for an object, we add it to our online ‘impact risk’ table, and asteroid observers can then prioritize that object for further observation. The more measurements made of the object’s position over time, the better we can predict its future path.
In most cases, the new measurements mean the object can be removed from the risk list because the uncertainties in the orbital path are reduced and the possibility of impact is ruled out.
More recently, CNEOS also developed a system called Scout to provide more immediate and automatic trajectory analyses for the most recently discovered objects, even before independent observatories confirm their discovery. Operating around the clock, the Scout system not only notifies observers of the highest priority objects to observe at any given time, it also immediately alerts the Planetary Defense Coordination Office of any possible imminent impacts within the next few hours or days.A recent example is the Scout-predicted impact of the small asteroid 2018 LA over Botswana, Africa.
More Hunting to Do
With the addition of more capable NASA-funded asteroid surveys over the years, NASA’s NEO Observations Program is responsible for over 90 percent of near-Earth asteroid and comet discoveries. There are now over 18,000 known NEOs and the discovery rate averages about 40 per week.
Although the original Congressional goal from 1998 has been exceeded and much progress has been made in asteroid discovery and tracking over the past two decades, the work isn’t over. In 2005, Congress established a new, much more ambitious goal for the NEO Observations Program — to discover 90 percent of the NEOs down to the much smaller size of 450 feet (140 meters), and to do so by the year 2020.
These smaller asteroids may not present a threat of global catastrophe if they impact Earth, but they could still cause massive regional devastation and loss of life, especially if they occur near a metropolitan area. CNEOS continues to make improvements to its orbital analysis tools, image and graphic presentation capabilities, and updates of its websites to quickly and accurately provide the very latest information on NEOs to PDCO, the astronomical community and the public.
More information about CNEOS, asteroids and near-Earth objects can be found at:
To fully appreciate why two EPA regions are working to improve the Delaware River Watershed, it helps to experience the area’s natural wonders.
