New Year’s Day clouds over El Paso

Patricia Lea wrote: “Happy New Year’s from El Paso, Texas. Friend walking to a restaurant and spotted these lenticular clouds. Enjoy.” Thanks, Patricia and friend!

Read more and see more photos: Lenticular clouds look like UFOs

from EarthSky http://bit.ly/2TlhpmN

Patricia Lea wrote: “Happy New Year’s from El Paso, Texas. Friend walking to a restaurant and spotted these lenticular clouds. Enjoy.” Thanks, Patricia and friend!

Read more and see more photos: Lenticular clouds look like UFOs

from EarthSky http://bit.ly/2TlhpmN

Earth closest to sun on January 2-3

Cartoon above via Sara Zimmerman at Unearthed Comics.

Tonight – January 2, 2019 according to clocks in the Americas – we reach Earth’s closest point to the sun for this entire year. That closest point comes at 11:20 p.m. CST (central U.S.) on January 2. It’ll be the morning of January 3 for Europe and Africa … later in the day January 3 for the rest of the world (January 3 at 5:20 UTC; translate to your time zone). Astronomers call this special point in our orbit perihelion, from the Greek roots peri meaning near and helios meaning sun.

At its closest point, Earth swings to within 91,403,554 miles (147,099,761 km) of the sun. That’s in contrast to six months from now, when the Earth reaches aphelion – its most distant point – on July 4, 2019. Then we’ll be 94,513,221 miles (152,104,285 km) from the sun.

In other words, Earth is about 3 million miles (5 million km) closer to the sun in early January than it is in early July. That’s always the case. Earth is closest to the sun every year in early January, when it’s winter for the Northern Hemisphere.

We’re farthest away from the sun in early July, during our Northern Hemisphere summer.

Source: Fred Espenak’s Earth at perihelion and aphelion, 2001 to 2100

Image via NASA

So you see there’s not a huge distance difference between perihelion and aphelion. Earth’s orbit is very nearly circular. Thus it’s not our distance from the sun – but instead the tilt of our world’s axis – that creates winter and summer on Earth.

In winter, your part of Earth is tilted away from the sun. In summer, your part of Earth is tilted toward the sun. The day of maximum tilt toward or away from the sun is the December or June solstice.

Though not responsible for the seasons, Earth’s closest and farthest points to the sun do affect seasonal lengths. When the Earth comes closest to the sun for the year, as around now, our world is moving fastest in orbit around the sun. Earth is rushing along now at almost 19 miles per second (30.3 km/sec) – moving about a kilometer per second faster than when Earth is farthest from the sun in early July. Thus the Northern Hemisphere winter and – simultaneously – Southern Hemisphere summer are the shortest seasons as Earth rushes from the solstice in December to the equinox in March.

In the Northern Hemisphere, the summer season (June solstice to September equinox) lasts nearly 5 days longer than our winter season. And, of course, the corresponding seasons in the Southern Hemisphere are opposite. Southern Hemisphere winter is nearly 5 days longer than Southern Hemisphere summer.

It’s all due to the shape of Earth’s orbit. The shape is an ellipse, like a circle someone sat down on and squashed. The elliptical shape of Earth’s orbit causes the variation in the length of the seasons – and brings us closest to the sun in January.

Image Credit: Dna-webmaster

Bottom line: In 2019, Earth’s closest point to the sun – called its perihelion – comes on January 3 at 5:20 Universal Time (on January 2 at 11:20 p.m. CST).

A planisphere is virtually indispensable for beginning stargazers. Order your EarthSky Planisphere today!

Are the December solstice and January perihelion related?

from EarthSky http://bit.ly/2Sythlm

Cartoon above via Sara Zimmerman at Unearthed Comics.

Tonight – January 2, 2019 according to clocks in the Americas – we reach Earth’s closest point to the sun for this entire year. That closest point comes at 11:20 p.m. CST (central U.S.) on January 2. It’ll be the morning of January 3 for Europe and Africa … later in the day January 3 for the rest of the world (January 3 at 5:20 UTC; translate to your time zone). Astronomers call this special point in our orbit perihelion, from the Greek roots peri meaning near and helios meaning sun.

At its closest point, Earth swings to within 91,403,554 miles (147,099,761 km) of the sun. That’s in contrast to six months from now, when the Earth reaches aphelion – its most distant point – on July 4, 2019. Then we’ll be 94,513,221 miles (152,104,285 km) from the sun.

In other words, Earth is about 3 million miles (5 million km) closer to the sun in early January than it is in early July. That’s always the case. Earth is closest to the sun every year in early January, when it’s winter for the Northern Hemisphere.

We’re farthest away from the sun in early July, during our Northern Hemisphere summer.

Source: Fred Espenak’s Earth at perihelion and aphelion, 2001 to 2100

Image via NASA

So you see there’s not a huge distance difference between perihelion and aphelion. Earth’s orbit is very nearly circular. Thus it’s not our distance from the sun – but instead the tilt of our world’s axis – that creates winter and summer on Earth.

In winter, your part of Earth is tilted away from the sun. In summer, your part of Earth is tilted toward the sun. The day of maximum tilt toward or away from the sun is the December or June solstice.

Though not responsible for the seasons, Earth’s closest and farthest points to the sun do affect seasonal lengths. When the Earth comes closest to the sun for the year, as around now, our world is moving fastest in orbit around the sun. Earth is rushing along now at almost 19 miles per second (30.3 km/sec) – moving about a kilometer per second faster than when Earth is farthest from the sun in early July. Thus the Northern Hemisphere winter and – simultaneously – Southern Hemisphere summer are the shortest seasons as Earth rushes from the solstice in December to the equinox in March.

In the Northern Hemisphere, the summer season (June solstice to September equinox) lasts nearly 5 days longer than our winter season. And, of course, the corresponding seasons in the Southern Hemisphere are opposite. Southern Hemisphere winter is nearly 5 days longer than Southern Hemisphere summer.

It’s all due to the shape of Earth’s orbit. The shape is an ellipse, like a circle someone sat down on and squashed. The elliptical shape of Earth’s orbit causes the variation in the length of the seasons – and brings us closest to the sun in January.

Image Credit: Dna-webmaster

Bottom line: In 2019, Earth’s closest point to the sun – called its perihelion – comes on January 3 at 5:20 Universal Time (on January 2 at 11:20 p.m. CST).

A planisphere is virtually indispensable for beginning stargazers. Order your EarthSky Planisphere today!

Are the December solstice and January perihelion related?

from EarthSky http://bit.ly/2Sythlm

New Horizons sweeps past Ultima Thule

Left, a composite of 2 images taken via New Horizons. Scientists say it provides the best indication of Ultima Thule’s size and shape so far. Preliminary measurements of this Kuiper Belt object suggest it’s approximately 20 miles long by 10 miles wide (32 km by 16 km). Right, an artist’s impression of one possible appearance of Ultima Thule, based on the actual image at left. The direction of Ultima’s spin axis is indicated by the arrows. Image via NASA/JHUAPL/SwRI; sketch courtesy of James Tuttle Keane.

The New Year has brought with it a couple of astounding new space records. On December 31, NASA’s OSIRIS-REx spacecraft successfully moved into orbit around the smallest space body yet, a near-Earth asteroid called Bennu. Just hours later, in the early hours of New Year’s Day according to clocks in the Americas, the New Horizons spacecraft – also a NASA craft, launched from Earth in 2006 and made famous in 2015 for its once-in-a-lifetime encounter with Pluto – made history again with the most distant spacecraft encounter yet. New Horizons swept past an object in the Kuiper Belt – known as Ultima Thule – on January 1, 2019 at 06:33 UTC (12:33 a.m. EST).

Signals confirming the spacecraft had survived the encounter and had filled its digital recorders with science data on Ultima Thule reached the mission operations center at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland almost exactly 10 hours later, at 14:29 UTC (10:29 a.m. EST).

It took that long for New Horizons to send back its data from this distant object, some 4 billion miles from our sun.

New Horizons team members awaiting a signal from New Horizons, at the Mission Operations Center of the Johns Hopkins University Applied Physics Laboratory in Maryland, on January 1, 2019. Photo via NASA Flickr/Bill Ingalls.

New Horizons’ path took it about 2,200 miles (3,500 km) from Ultima Thule (which, by the way, is officially designated 2014 MU69). The decision to take that path – instead of a hazard-avoiding detour that would have pushed it three times farther out – was made as recently as mid-December. Space scientists made the decision only after observations from New Horizons itself revealed no rings, no small moons, no potential hazards, in Ultima Thule’s vicinity.

Still, space scientists couldn’t be sure the spacecraft would survive the encounter. They at times looked tense while awaiting word from the spacecraft’s various systems. Then, one by one, all were confirmed as healthy and the mood turned jubilant.

The images on this page are just preliminary. New Horizons spacecraft will continue downloading images and other data in the days and months ahead, completing the return of all science data over the next 20 months.

Updated view of #UltimaThule based on better imagery from @NASANewHorizons … 35 km x 15 km with dogbone shape. #UltimaFlyby pic.twitter.com/QiAHECPfZN

— Alan Boyle (@b0yle) January 1, 2019

Principal Investigator Alan Stern, of the Southwest Research Institute in Boulder, Colorado, said:

New Horizons performed as planned today, conducting the farthest exploration of any world in history … The data we have look fantastic and we’re already learning about Ultima from up close. From here out the data will just get better and better!

Prior to the encounter, scientists had been puzzling over the light reflected from Ultima Thule. The spacecraft had been taking hundreds of images to measure Ultima’s brightness, but those recent measurements appeared to be at odds with a 2017 observation, made when Ultima Thule covered (occulted) a star as seen from Earth. In 2017, based on the occultation data, scientists thought Ultima Thule might be not one, but two bodies orbiting around each other. If there aren’t two objects there, the science team said in 2017, then this little Kuiper Belt object might have a pronounced elongated shape.

And indeed its shape does appear elongated, although more is sure to be revealed about its shape and spin axis in the days ahead. For now, images taken during the spacecraft’s approach show that Ultima Thule might have a shape similar to a bowling pin, spinning end over end, with dimensions of approximately 20 by 10 miles (32 by 16 km).

Flyby data have already solved one of Ultima’s mysteries, showing that the Kuiper Belt object is spinning like a propeller with the axis pointing approximately toward New Horizons. This explains why, in earlier images taken before Ultima was resolved, its brightness didn’t appear to vary as it rotated.

The team has still not determined Ultima Thule’s rotation period.

As the science data began its initial return to Earth, mission team members and leadership reveled in the excitement of the first exploration of this distant region of space. Johns Hopkins Applied Physics Laboratory Director Ralph Semmel commented:

New Horizons holds a dear place in our hearts as an intrepid and persistent little explorer, as well as a great photographer. This flyby marks a first for all of us — APL, NASA, the nation and the world — and it is a great credit to the bold team of scientists and engineers who brought us to this point.

Now, almost 13 years after the launch of New Horizons, scientists say the spacecraft will continue its exploration of the Kuiper Belt until at least 2021. Team members plan to propose more Kuiper Belt exploration.

Bottom line: Since encountering Pluto in 2015, New Horizons has been heading outward. It’s now survived a sweep past its next target, Ultima Thule, now the most distant object visited by a spacecraft from Earth.

Via Johns Hopkins

from EarthSky http://bit.ly/2R1v9X3

Left, a composite of 2 images taken via New Horizons. Scientists say it provides the best indication of Ultima Thule’s size and shape so far. Preliminary measurements of this Kuiper Belt object suggest it’s approximately 20 miles long by 10 miles wide (32 km by 16 km). Right, an artist’s impression of one possible appearance of Ultima Thule, based on the actual image at left. The direction of Ultima’s spin axis is indicated by the arrows. Image via NASA/JHUAPL/SwRI; sketch courtesy of James Tuttle Keane.

The New Year has brought with it a couple of astounding new space records. On December 31, NASA’s OSIRIS-REx spacecraft successfully moved into orbit around the smallest space body yet, a near-Earth asteroid called Bennu. Just hours later, in the early hours of New Year’s Day according to clocks in the Americas, the New Horizons spacecraft – also a NASA craft, launched from Earth in 2006 and made famous in 2015 for its once-in-a-lifetime encounter with Pluto – made history again with the most distant spacecraft encounter yet. New Horizons swept past an object in the Kuiper Belt – known as Ultima Thule – on January 1, 2019 at 06:33 UTC (12:33 a.m. EST).

Signals confirming the spacecraft had survived the encounter and had filled its digital recorders with science data on Ultima Thule reached the mission operations center at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland almost exactly 10 hours later, at 14:29 UTC (10:29 a.m. EST).

It took that long for New Horizons to send back its data from this distant object, some 4 billion miles from our sun.

New Horizons team members awaiting a signal from New Horizons, at the Mission Operations Center of the Johns Hopkins University Applied Physics Laboratory in Maryland, on January 1, 2019. Photo via NASA Flickr/Bill Ingalls.

New Horizons’ path took it about 2,200 miles (3,500 km) from Ultima Thule (which, by the way, is officially designated 2014 MU69). The decision to take that path – instead of a hazard-avoiding detour that would have pushed it three times farther out – was made as recently as mid-December. Space scientists made the decision only after observations from New Horizons itself revealed no rings, no small moons, no potential hazards, in Ultima Thule’s vicinity.

Still, space scientists couldn’t be sure the spacecraft would survive the encounter. They at times looked tense while awaiting word from the spacecraft’s various systems. Then, one by one, all were confirmed as healthy and the mood turned jubilant.

The images on this page are just preliminary. New Horizons spacecraft will continue downloading images and other data in the days and months ahead, completing the return of all science data over the next 20 months.

Updated view of #UltimaThule based on better imagery from @NASANewHorizons … 35 km x 15 km with dogbone shape. #UltimaFlyby pic.twitter.com/QiAHECPfZN

— Alan Boyle (@b0yle) January 1, 2019

Principal Investigator Alan Stern, of the Southwest Research Institute in Boulder, Colorado, said:

New Horizons performed as planned today, conducting the farthest exploration of any world in history … The data we have look fantastic and we’re already learning about Ultima from up close. From here out the data will just get better and better!

Prior to the encounter, scientists had been puzzling over the light reflected from Ultima Thule. The spacecraft had been taking hundreds of images to measure Ultima’s brightness, but those recent measurements appeared to be at odds with a 2017 observation, made when Ultima Thule covered (occulted) a star as seen from Earth. In 2017, based on the occultation data, scientists thought Ultima Thule might be not one, but two bodies orbiting around each other. If there aren’t two objects there, the science team said in 2017, then this little Kuiper Belt object might have a pronounced elongated shape.

And indeed its shape does appear elongated, although more is sure to be revealed about its shape and spin axis in the days ahead. For now, images taken during the spacecraft’s approach show that Ultima Thule might have a shape similar to a bowling pin, spinning end over end, with dimensions of approximately 20 by 10 miles (32 by 16 km).

Flyby data have already solved one of Ultima’s mysteries, showing that the Kuiper Belt object is spinning like a propeller with the axis pointing approximately toward New Horizons. This explains why, in earlier images taken before Ultima was resolved, its brightness didn’t appear to vary as it rotated.

The team has still not determined Ultima Thule’s rotation period.

As the science data began its initial return to Earth, mission team members and leadership reveled in the excitement of the first exploration of this distant region of space. Johns Hopkins Applied Physics Laboratory Director Ralph Semmel commented:

New Horizons holds a dear place in our hearts as an intrepid and persistent little explorer, as well as a great photographer. This flyby marks a first for all of us — APL, NASA, the nation and the world — and it is a great credit to the bold team of scientists and engineers who brought us to this point.

Now, almost 13 years after the launch of New Horizons, scientists say the spacecraft will continue its exploration of the Kuiper Belt until at least 2021. Team members plan to propose more Kuiper Belt exploration.

Bottom line: Since encountering Pluto in 2015, New Horizons has been heading outward. It’s now survived a sweep past its next target, Ultima Thule, now the most distant object visited by a spacecraft from Earth.

Via Johns Hopkins

from EarthSky http://bit.ly/2R1v9X3

Spacecraft orbits tiny Bennu, breaks record

Yesterday – while many on Earth were ringing in the New Year – a NASA spacecraft 70 million miles (110 million km) away was breaking a space exploration record. NASA’s OSIRIS-REx spacecraft carried out a single, eight-second burn of its thrusters and entered into orbit around near-Earth asteroid Bennu, making Bennu the smallest object yet to be orbited by a spacecraft. And Bennu is, indeed, very small. It has a mean diameter of approximately 1,614 feet (0.306 miles; 492 meters). The burn took place on December 31, 2018 at 18:43 UTC (2:43 p.m. EST). Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson said:

The team [executed] the orbit-insertion maneuver perfectly. With the navigation campaign coming to an end, we are looking forward to the scientific mapping and sample site selection phase of the mission.

He added:

Entering orbit around Bennu is an amazing accomplishment that our team has been planning for years.

A statement from the team pointed out that Bennu – named for an ancient Egyptian mythological bird associated with the sun, creation, and rebirth – has barely enough gravity to keep a vehicle in a stable orbit.

The previous record-holder for closest orbit of a planetary body was the Rosetta spacecraft, which orbited about four miles (seven km) from the center of comet 67P/Churyumov-Gerasimenko in May 2016. OSIRIS-REx is much closer to Bennu, about a mile (1.75 km) from its center. This distance is necessary to keep the spacecraft locked to Bennu, these space scientists said, whose gravity is only 5-millionths as strong as Earth’s.

The spacecraft is scheduled to orbit Bennu through mid-February at a leisurely 62 hours per orbit.

This mosaic image of asteroid Bennu is composed of 12 PolyCam images collected on December 2, 2018 by the OSIRIS-REx spacecraft from a range of 15 miles (24 km). Image via NASA/Goddard/University of Arizona.

OSIRIS-REx’s flight dynamics system manager Mike Moreau, who is based at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, commented:

Our orbit design is highly dependent on Bennu’s physical properties, such as its mass and gravity field, which we didn’t know before we arrived.

Up until now, we had to account for a wide variety of possible scenarios in our computer simulations to make sure we could safely navigate the spacecraft so close to Bennu. As the team learned more about the asteroid, we incorporated new information to hone in on the final orbit design.

Even though OSIRIS-REx is in the most stable orbit possible, the team said, Bennu’s gravitational pull is so tenuous that keeping the spacecraft safe will require occasional adjustments. Dan Wibben, OSIRIS-REx maneuver and trajectory design lead at KinetX Aerospace in Simi Valley, California, said:

The gravity of Bennu is so small, forces like solar radiation and thermal pressure from Bennu’s surface become much more relevant and can push the spacecraft around in its orbit much more than if it were orbiting around Earth or Mars, where gravity is by far the most dominant force.

One critical objective of this orbital phase, the team said, is to get a better handle on Bennu’s mass and gravity, features that will influence the planning of the rest of the mission, notably the short touchdown on the surface for sample collection in 2020. In the case of Bennu, scientists can only measure these features by getting OSIRIS-REx very close to the surface to see how its trajectory bends from Bennu’s gravitational pull.

The OSIRIS-REx mission is scheduled to deliver the sample to Earth in September 2023.

Asteroid Bennu is considered a potentially hazardous object because its orbit carries it near Earth and it is large enough to cause significant damage in the event of an impact. It has a cumulative 1-in-2,700 chance of impacting Earth between 2175 and 2199.

Read more from University of Arizona.

Artist’s concept of OSIRIS-REx spacecraft at asteroid Bennu. The craft is scheduled for a sample collection in 2020 and sample return to Earth in 2023. Image via Heather Roper/University of Arizona.

Bottom line: NASA’s OSIRIS-REx spacecraft successful carried out a burn on on December 31, 2018 at 18:43 UTC (2:43 p.m. EST) and thereby went into orbit around near-Earth asteroid Bennu. The maneuver makes Bennu the smallest object yet to be orbited by a spacecraft.

from EarthSky http://bit.ly/2EY5UxQ

Yesterday – while many on Earth were ringing in the New Year – a NASA spacecraft 70 million miles (110 million km) away was breaking a space exploration record. NASA’s OSIRIS-REx spacecraft carried out a single, eight-second burn of its thrusters and entered into orbit around near-Earth asteroid Bennu, making Bennu the smallest object yet to be orbited by a spacecraft. And Bennu is, indeed, very small. It has a mean diameter of approximately 1,614 feet (0.306 miles; 492 meters). The burn took place on December 31, 2018 at 18:43 UTC (2:43 p.m. EST). Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson said:

The team [executed] the orbit-insertion maneuver perfectly. With the navigation campaign coming to an end, we are looking forward to the scientific mapping and sample site selection phase of the mission.

He added:

Entering orbit around Bennu is an amazing accomplishment that our team has been planning for years.

A statement from the team pointed out that Bennu – named for an ancient Egyptian mythological bird associated with the sun, creation, and rebirth – has barely enough gravity to keep a vehicle in a stable orbit.

The previous record-holder for closest orbit of a planetary body was the Rosetta spacecraft, which orbited about four miles (seven km) from the center of comet 67P/Churyumov-Gerasimenko in May 2016. OSIRIS-REx is much closer to Bennu, about a mile (1.75 km) from its center. This distance is necessary to keep the spacecraft locked to Bennu, these space scientists said, whose gravity is only 5-millionths as strong as Earth’s.

The spacecraft is scheduled to orbit Bennu through mid-February at a leisurely 62 hours per orbit.

This mosaic image of asteroid Bennu is composed of 12 PolyCam images collected on December 2, 2018 by the OSIRIS-REx spacecraft from a range of 15 miles (24 km). Image via NASA/Goddard/University of Arizona.

OSIRIS-REx’s flight dynamics system manager Mike Moreau, who is based at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, commented:

Our orbit design is highly dependent on Bennu’s physical properties, such as its mass and gravity field, which we didn’t know before we arrived.

Up until now, we had to account for a wide variety of possible scenarios in our computer simulations to make sure we could safely navigate the spacecraft so close to Bennu. As the team learned more about the asteroid, we incorporated new information to hone in on the final orbit design.

Even though OSIRIS-REx is in the most stable orbit possible, the team said, Bennu’s gravitational pull is so tenuous that keeping the spacecraft safe will require occasional adjustments. Dan Wibben, OSIRIS-REx maneuver and trajectory design lead at KinetX Aerospace in Simi Valley, California, said:

The gravity of Bennu is so small, forces like solar radiation and thermal pressure from Bennu’s surface become much more relevant and can push the spacecraft around in its orbit much more than if it were orbiting around Earth or Mars, where gravity is by far the most dominant force.

One critical objective of this orbital phase, the team said, is to get a better handle on Bennu’s mass and gravity, features that will influence the planning of the rest of the mission, notably the short touchdown on the surface for sample collection in 2020. In the case of Bennu, scientists can only measure these features by getting OSIRIS-REx very close to the surface to see how its trajectory bends from Bennu’s gravitational pull.

The OSIRIS-REx mission is scheduled to deliver the sample to Earth in September 2023.

Asteroid Bennu is considered a potentially hazardous object because its orbit carries it near Earth and it is large enough to cause significant damage in the event of an impact. It has a cumulative 1-in-2,700 chance of impacting Earth between 2175 and 2199.

Read more from University of Arizona.

Artist’s concept of OSIRIS-REx spacecraft at asteroid Bennu. The craft is scheduled for a sample collection in 2020 and sample return to Earth in 2023. Image via Heather Roper/University of Arizona.

Bottom line: NASA’s OSIRIS-REx spacecraft successful carried out a burn on on December 31, 2018 at 18:43 UTC (2:43 p.m. EST) and thereby went into orbit around near-Earth asteroid Bennu. The maneuver makes Bennu the smallest object yet to be orbited by a spacecraft.

from EarthSky http://bit.ly/2EY5UxQ

January guide to the bright planets

The New Year starts with the waning crescent moon cruising down a cascade of morning planets, ambling by Venus first, Jupiter next and Mercury last. Read more

Click the name of a planet to learn more about its visibility in January 2019: Venus, Jupiter, Saturn, Mars and Mercury

The New Year starts with the waning crescent moon cruising down a cascade of morning planets, ambling by Venus first, Jupiter next and Mercury last. Read more

Venus is the brightest planet, beaming mightily in the east before sunrise. This world will reach a milestone in the morning sky on January 5 or 6, 2019, depending on your time zone, as this blazing world reaches its greatest elongation from the sun. In other words, January 2019 is a great month for watching Venus in the morning sky.

Depending on your time zone, Venus will reach its greatest morning elongation on January 5 or 6, 2019, the same date that the new moon partially eclipses the sun. Read more.

The month starts out with Venus shining above Jupiter in the morning sky, yet the month ends with Jupiter shining above Venus. Day by day, Jupiter climbs upward, away from the sunrise, while Venus sinks downward, toward the rising sun. The two will meet for a conjunction in the morning sky on January 22, 2019.

After this month, Venus will spend less time in the predawn sky but will still be plenty visible at dawn. At mid-northern latitudes, Venus will rise before astronomical twilight (dawn’s first light) until mid-March 2019; and at temperate latitudes in the Southern Hemisphere, Venus will rise before astronomical twilight until the end of May 2019.

Click here to find out when astronomical twilight comes to your sky, remembering to check the astronomical twilight box.

Watch for the waning crescent moon to join Venus in the morning sky for a few days, centered on or near New Year’s Day. Then, at the month’s end, watch for the waning crescent to pair up with Venus again around January 31.

At mid-northern latitudes, Venus rises about 3 1/2 hours before sunrise in early January. By the month’s end, that’ll taper to about 3 hours.

At temperate latitudes in the Southern Hemisphere, Venus rises about 3 hours before sunup in early January. By the month’s end, that’ll increase to nearly 3 1/2 hours.

The 2019 lunar calendars are here! Order yours before they’re gone. Makes a great gift.

The two brightest planets – Venus and Jupiter – meet up for a conjunction on January 22, 2019. Read more.

Jupiter is the second-brightest planet, after Venus. The king planet is found below Venus in the predawn/dawn sky at the beginning of the month, yet above Venus at the month’s end. The two will meet up for a conjunction in the morning sky on January 22, 2019, or one month after the Jupiter/Mercury conjunction in the morning sky on December 21, 2018.

If you’re up during the predawn hours, you may notice a bright ruddy star in the vicinity of Jupiter on the sky’s dome. That’s Antares, the brightest star in the constellation Scorpius the Scorpion. Although Jupiter shines in the vicinity Antares all year long, Jupiter can be seen to wander relative to this “fixed” star of the zodiac. Jupiter travels eastward, away from Antares, until April 10, 2019. Then, for a period of four months (April 10 to August 11, 2019), Jupiter actually moves in retrograde (or westward), closing the gap between itself and the star Antares. Midway through this retrograde, Jupiter will reach opposition on June 10, 2019, to shine at its brilliant best for the year.

Watch for the waning crescent moon to swing by Jupiter around January 2 or 3, and then to revisit Jupiter near the month’s end, on January 30 and 31.

From mid-northern latitudes, Jupiter rises about 2 1/2 hours before the sun in early January. By the month’s end, that’ll increase to about 3 1/2 hours.

From temperate latitudes in the Southern Hemisphere, Jupiter comes up about 2 hours before sunrise at the beginning of the month. By the month’s end, it’s around 3 1/2 hours.

Near the month’s end, use the waning crescent moon and the two dazzling morning planets, Venus and Jupiter, to help guide your eye to Saturn. Read more.

Saturn swings over to the morning sky on January 2, 2019, leaving Mars as the only bright planet to adorn the January 2019 evening sky. For the most part, Saturn remains hidden in the glare of sunrise until the month’s end. Starting on or near January 30, use the waning crescent moon and the two brilliant planets, Venus and Jupiter, to help guide you to Saturn’s place near the horizon as darkness begins to give way to dawn.

Mercury and Saturn actually have a conjunction in the morning sky on January 13, 2019. But these two worlds will be so deeply buried in the glare of morning twilight that they’ll be next to impossible to see.

The first several mornings of the New Year 2019 feature the waning crescent moon and three morning planets. You may need binoculars to catch Mercury. Read more

Mercury, the innermost planet of the solar system, reached its moment of glory in the morning sky with the conjunction of Mercury and Jupiter on December 21, 2018. In January 2019, your best chance of catching Mercury comes very early in the month. The slender waning crescent moon pairs up with Mercury on or near January 4, providing what may be your last chance to catch Mercury in the January morning sky. After that, Mercury quickly plunges sunward, to disappear in the glare of morning twilight.

Mercury will have shifted over to the evening sky by February 2019. Mercury’s apparition in the evening sky will be especially favorable for the Northern Hemisphere in the last few weeks of February and early March 2019.

Look for the moon to pair up with Mars for a few evenings, centered on or near January 12. Read more.

Mars is the only bright planet to appear in the January evening sky. Fortunately, though dimming somewhat through the month, Mars remains modestly-bright and beautiful, shining as brilliantly a 1st-magnitude star. Moreover, Mars stays out till late evening all throughout January 2019 in both the Northern and Southern Hemispheres.

Click here for recommended sky almanacs providing you with the setting times for Mars.

Watch for the moon to shine in the vicinity of Mars for several evenings, centered on or near January 12.

Once you’ve found Mars, you might want to try your luck with a much fainter planet planet, Uranus. 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.

Skywatcher, by Predrag Agatonovic.

Bottom line: In January 2019, Mars is the sole bright evening planet, while Venus and Jupiter lord over the morning sky. Mercury fades from view as a morning planet in early January whereas Saturn becomes visible near the month’s end. Click here for recommended almanacs; they can help you know when the planets rise, transit and set in your sky.

Don’t miss anything. Subscribe to EarthSky News by email

Visit EarthSky’s Best Places to Stargaze, and recommend a place we can all enjoy. Zoom out for worldwide map.

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from EarthSky http://bit.ly/1YD00CF

The New Year starts with the waning crescent moon cruising down a cascade of morning planets, ambling by Venus first, Jupiter next and Mercury last. Read more

Click the name of a planet to learn more about its visibility in January 2019: Venus, Jupiter, Saturn, Mars and Mercury

The New Year starts with the waning crescent moon cruising down a cascade of morning planets, ambling by Venus first, Jupiter next and Mercury last. Read more

Venus is the brightest planet, beaming mightily in the east before sunrise. This world will reach a milestone in the morning sky on January 5 or 6, 2019, depending on your time zone, as this blazing world reaches its greatest elongation from the sun. In other words, January 2019 is a great month for watching Venus in the morning sky.

Depending on your time zone, Venus will reach its greatest morning elongation on January 5 or 6, 2019, the same date that the new moon partially eclipses the sun. Read more.

The month starts out with Venus shining above Jupiter in the morning sky, yet the month ends with Jupiter shining above Venus. Day by day, Jupiter climbs upward, away from the sunrise, while Venus sinks downward, toward the rising sun. The two will meet for a conjunction in the morning sky on January 22, 2019.

After this month, Venus will spend less time in the predawn sky but will still be plenty visible at dawn. At mid-northern latitudes, Venus will rise before astronomical twilight (dawn’s first light) until mid-March 2019; and at temperate latitudes in the Southern Hemisphere, Venus will rise before astronomical twilight until the end of May 2019.

Click here to find out when astronomical twilight comes to your sky, remembering to check the astronomical twilight box.

Watch for the waning crescent moon to join Venus in the morning sky for a few days, centered on or near New Year’s Day. Then, at the month’s end, watch for the waning crescent to pair up with Venus again around January 31.

At mid-northern latitudes, Venus rises about 3 1/2 hours before sunrise in early January. By the month’s end, that’ll taper to about 3 hours.

At temperate latitudes in the Southern Hemisphere, Venus rises about 3 hours before sunup in early January. By the month’s end, that’ll increase to nearly 3 1/2 hours.

The 2019 lunar calendars are here! Order yours before they’re gone. Makes a great gift.

The two brightest planets – Venus and Jupiter – meet up for a conjunction on January 22, 2019. Read more.

Jupiter is the second-brightest planet, after Venus. The king planet is found below Venus in the predawn/dawn sky at the beginning of the month, yet above Venus at the month’s end. The two will meet up for a conjunction in the morning sky on January 22, 2019, or one month after the Jupiter/Mercury conjunction in the morning sky on December 21, 2018.

If you’re up during the predawn hours, you may notice a bright ruddy star in the vicinity of Jupiter on the sky’s dome. That’s Antares, the brightest star in the constellation Scorpius the Scorpion. Although Jupiter shines in the vicinity Antares all year long, Jupiter can be seen to wander relative to this “fixed” star of the zodiac. Jupiter travels eastward, away from Antares, until April 10, 2019. Then, for a period of four months (April 10 to August 11, 2019), Jupiter actually moves in retrograde (or westward), closing the gap between itself and the star Antares. Midway through this retrograde, Jupiter will reach opposition on June 10, 2019, to shine at its brilliant best for the year.

Watch for the waning crescent moon to swing by Jupiter around January 2 or 3, and then to revisit Jupiter near the month’s end, on January 30 and 31.

From mid-northern latitudes, Jupiter rises about 2 1/2 hours before the sun in early January. By the month’s end, that’ll increase to about 3 1/2 hours.

From temperate latitudes in the Southern Hemisphere, Jupiter comes up about 2 hours before sunrise at the beginning of the month. By the month’s end, it’s around 3 1/2 hours.

Near the month’s end, use the waning crescent moon and the two dazzling morning planets, Venus and Jupiter, to help guide your eye to Saturn. Read more.

Saturn swings over to the morning sky on January 2, 2019, leaving Mars as the only bright planet to adorn the January 2019 evening sky. For the most part, Saturn remains hidden in the glare of sunrise until the month’s end. Starting on or near January 30, use the waning crescent moon and the two brilliant planets, Venus and Jupiter, to help guide you to Saturn’s place near the horizon as darkness begins to give way to dawn.

Mercury and Saturn actually have a conjunction in the morning sky on January 13, 2019. But these two worlds will be so deeply buried in the glare of morning twilight that they’ll be next to impossible to see.

The first several mornings of the New Year 2019 feature the waning crescent moon and three morning planets. You may need binoculars to catch Mercury. Read more

Mercury, the innermost planet of the solar system, reached its moment of glory in the morning sky with the conjunction of Mercury and Jupiter on December 21, 2018. In January 2019, your best chance of catching Mercury comes very early in the month. The slender waning crescent moon pairs up with Mercury on or near January 4, providing what may be your last chance to catch Mercury in the January morning sky. After that, Mercury quickly plunges sunward, to disappear in the glare of morning twilight.

Mercury will have shifted over to the evening sky by February 2019. Mercury’s apparition in the evening sky will be especially favorable for the Northern Hemisphere in the last few weeks of February and early March 2019.

Look for the moon to pair up with Mars for a few evenings, centered on or near January 12. Read more.

Mars is the only bright planet to appear in the January evening sky. Fortunately, though dimming somewhat through the month, Mars remains modestly-bright and beautiful, shining as brilliantly a 1st-magnitude star. Moreover, Mars stays out till late evening all throughout January 2019 in both the Northern and Southern Hemispheres.

Click here for recommended sky almanacs providing you with the setting times for Mars.

Watch for the moon to shine in the vicinity of Mars for several evenings, centered on or near January 12.

Once you’ve found Mars, you might want to try your luck with a much fainter planet planet, Uranus. 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.

Skywatcher, by Predrag Agatonovic.

Bottom line: In January 2019, Mars is the sole bright evening planet, while Venus and Jupiter lord over the morning sky. Mercury fades from view as a morning planet in early January whereas Saturn becomes visible near the month’s end. Click here for recommended almanacs; they can help you know when the planets rise, transit and set in your sky.

Don’t miss anything. Subscribe to EarthSky News by email

Visit EarthSky’s Best Places to Stargaze, and recommend a place we can all enjoy. Zoom out for worldwide map.

Help EarthSky keep going! Donate now.

from EarthSky http://bit.ly/1YD00CF

Dark skies for 2019’s Quadrantid meteors

View larger. | In 2014, as the Quadrantids were flying, those at far northern latitudes were seeing auroras. Photo by Tommy Eliassen.

The Quadrantid meteor shower is 2019’s first major meteor shower. We’ll have moon-free skies for the peak this year, expected late night January 3 until dawn January 4. Although the Quadrantids have been known to produce some 50-100 meteors in a dark sky, their peak is extremely narrow, time-wise. Peaks of the Perseid or Geminid meteor showers persist for a day or more, allowing all time zones around the world to enjoy a good display of Perseids or Geminids. But the Quadrantids’ peak lasts only a few hours. So you have to be on the right part of Earth – preferably with the radiant high in your sky – in order to experience the peak of the Quadrantids. What’s more, the shower favors the Northern Hemisphere because its radiant point is so far north on the sky’s dome.

So you need some luck to see the Quadrantids, and being in the Northern Hemisphere does help. Who will see the 2019 shower? Keep in mind the prediction of the Quadrantid peak represents an educated guess, not an ironclad guarantee.

That said, in 2019, the International Meteor Organization gives the peak as January 4 at 2 UTC. If that prediction of the peak holds true, Europe – and areas of the globe surrounding Europe – have a good shot at viewing the shower at its best during the predawn hours on January 4.

Just know that meteor showers are notorious for defying the best-laid forecasts. Thus for the Quadrantids – as for any meteor shower – your best plan is simply to look for yourself.

Barry Simmons in Lake Martin, Alabama captured this Quadrantid meteor during the 2014 shower.

Anyplace at mid-northern and far-northern latitudes might be in a decent position to watch the Quadrantids in 2019, especially as there is no moonlight to ruin this year’s show.

There’s a new moon and partial solar eclipse on January 6, 2019, only two days after the predicted peak for the Quadrantids. You might see the slender waning crescent moon coming up shortly before sunrise January 4, but this fleeting and frail crescent won’t bother this year’s Quadrantid shower.

All other things being equal, for any meteor shower, you are likely to see the most meteors when the radiant is high in the sky.

In the case of the Quadrantid shower, the radiant point is seen highest in the sky in the dark hour before dawn.

From mid-northern latitudes, the radiant point for the Quadrantid shower doesn’t climb over the horizon until after midnight.

Where is the Quadrantids’ radiant point?

The radiant point of the Quadrantid shower makes an approximate right angle with the Big Dipper and the bright star Arcturus. If you trace the paths of the Quadrantid meteors backward, they appear to radiate from this point on the starry sky.

Now for our usual caveat. You don’t need to find the meteor shower radiant to see the Quadrantid meteors.

You just have to be at mid-northern or far-northern latitudes, up in the wee hours of the morning and hope the peak comes at just the right time to your part of the world.

The meteors will radiate from the northern sky, but appear in all parts of the sky.

The now-defunct constellation Quadrans Muralis, for which the Quadrantids are named. Image via Atlas Coelestis.

The Quadrantids are named for a constellation that no longer exists. Most meteor showers are named for the constellations from which they appear to radiate. So it is with the Quadrantids. But the Quadrantids’ constellation no longer exists, except in memory. The name Quadrantids comes from the constellation Quadrans Muralis (Mural Quadrant), created by the French astronomer Jerome Lalande in 1795. This now-obsolete constellation was located between the constellations of Bootes the Herdsman and Draco the Dragon. Where did it go?

To understand the history of the Quadrantids’ name, we have to go back to the earliest observations of this shower. In early January 1825, Antonio Brucalassi in Italy reported that:

… the atmosphere was traversed by a multitude of the luminous bodies known by the name of falling stars.

They appeared to radiate from Quadrans Muralis. In 1839, Adolphe Quetelet of Brussels Observatory in Belgium and Edward C. Herrick in Connecticut independently made the suggestion that the Quadrantids are an annual shower.

But, in 1922, the International Astronomical Union devised a list 88 modern constellations. The list was agreed upon by the International Astronomical Union at its inaugural General Assembly held in Rome in May 1922. It did not include a constellation Quadrans Muralis.

Today, this meteor shower retains the name Quadrantids, for the original and now obsolete constellation Quadrans Muralis.

The radiant point for the Quadrantids is now considered to be at the northern tip of Bootes, near the Big Dipper asterism in our sky, not far from Bootes’ brightest star Arcturus. It is very far north on the sky’s dome, which is why Southern Hemisphere observers probably won’t see many (if any) Quadrantid meteors. Most of the meteors simply won’t make it above the horizon for Southern Hemisphere skywatchers. But some might!

In 2003, Peter Jenniskens proposed that this object, 2003 EH1, is the parent body of the Quadrantid meteor shower.

Quadrantid meteors have a mysterious parent object. In 2003, astronomer Peter Jenniskens tentatively identified the parent body of the Quadrantids as the asteroid 2003 EH1. If indeed this body is the Quadrantids parent, then the Quadrantids, like the Geminid meteors, come from a rocky body – not an icy comet. Strange.

In turn, though, 2003 EH1 might be the same object as the comet C/1490 Y1, which was observed by Chinese, Japanese and Korean astronomers 500 years ago.

So the exact story behind the Quadrantids’ parent object remains somewhat mysterious.

Bottom line: The first major meteor shower of 2019, and every year, the Quadrantid meteor shower, will probably be at its best in the hours between midnight and dawn January 4. Fortunately, in 2019, the absence of moonlight means dark skies for this year’s annual Quadrantid meteor shower.

Celebrate 2019 with an EarthSky moon calendar!

from EarthSky http://bit.ly/2s2qBRm

View larger. | In 2014, as the Quadrantids were flying, those at far northern latitudes were seeing auroras. Photo by Tommy Eliassen.

The Quadrantid meteor shower is 2019’s first major meteor shower. We’ll have moon-free skies for the peak this year, expected late night January 3 until dawn January 4. Although the Quadrantids have been known to produce some 50-100 meteors in a dark sky, their peak is extremely narrow, time-wise. Peaks of the Perseid or Geminid meteor showers persist for a day or more, allowing all time zones around the world to enjoy a good display of Perseids or Geminids. But the Quadrantids’ peak lasts only a few hours. So you have to be on the right part of Earth – preferably with the radiant high in your sky – in order to experience the peak of the Quadrantids. What’s more, the shower favors the Northern Hemisphere because its radiant point is so far north on the sky’s dome.

So you need some luck to see the Quadrantids, and being in the Northern Hemisphere does help. Who will see the 2019 shower? Keep in mind the prediction of the Quadrantid peak represents an educated guess, not an ironclad guarantee.

That said, in 2019, the International Meteor Organization gives the peak as January 4 at 2 UTC. If that prediction of the peak holds true, Europe – and areas of the globe surrounding Europe – have a good shot at viewing the shower at its best during the predawn hours on January 4.

Just know that meteor showers are notorious for defying the best-laid forecasts. Thus for the Quadrantids – as for any meteor shower – your best plan is simply to look for yourself.

Barry Simmons in Lake Martin, Alabama captured this Quadrantid meteor during the 2014 shower.

Anyplace at mid-northern and far-northern latitudes might be in a decent position to watch the Quadrantids in 2019, especially as there is no moonlight to ruin this year’s show.

There’s a new moon and partial solar eclipse on January 6, 2019, only two days after the predicted peak for the Quadrantids. You might see the slender waning crescent moon coming up shortly before sunrise January 4, but this fleeting and frail crescent won’t bother this year’s Quadrantid shower.

All other things being equal, for any meteor shower, you are likely to see the most meteors when the radiant is high in the sky.

In the case of the Quadrantid shower, the radiant point is seen highest in the sky in the dark hour before dawn.

From mid-northern latitudes, the radiant point for the Quadrantid shower doesn’t climb over the horizon until after midnight.

Where is the Quadrantids’ radiant point?

The radiant point of the Quadrantid shower makes an approximate right angle with the Big Dipper and the bright star Arcturus. If you trace the paths of the Quadrantid meteors backward, they appear to radiate from this point on the starry sky.

Now for our usual caveat. You don’t need to find the meteor shower radiant to see the Quadrantid meteors.

You just have to be at mid-northern or far-northern latitudes, up in the wee hours of the morning and hope the peak comes at just the right time to your part of the world.

The meteors will radiate from the northern sky, but appear in all parts of the sky.

The now-defunct constellation Quadrans Muralis, for which the Quadrantids are named. Image via Atlas Coelestis.

The Quadrantids are named for a constellation that no longer exists. Most meteor showers are named for the constellations from which they appear to radiate. So it is with the Quadrantids. But the Quadrantids’ constellation no longer exists, except in memory. The name Quadrantids comes from the constellation Quadrans Muralis (Mural Quadrant), created by the French astronomer Jerome Lalande in 1795. This now-obsolete constellation was located between the constellations of Bootes the Herdsman and Draco the Dragon. Where did it go?

To understand the history of the Quadrantids’ name, we have to go back to the earliest observations of this shower. In early January 1825, Antonio Brucalassi in Italy reported that:

… the atmosphere was traversed by a multitude of the luminous bodies known by the name of falling stars.

They appeared to radiate from Quadrans Muralis. In 1839, Adolphe Quetelet of Brussels Observatory in Belgium and Edward C. Herrick in Connecticut independently made the suggestion that the Quadrantids are an annual shower.

But, in 1922, the International Astronomical Union devised a list 88 modern constellations. The list was agreed upon by the International Astronomical Union at its inaugural General Assembly held in Rome in May 1922. It did not include a constellation Quadrans Muralis.

Today, this meteor shower retains the name Quadrantids, for the original and now obsolete constellation Quadrans Muralis.

The radiant point for the Quadrantids is now considered to be at the northern tip of Bootes, near the Big Dipper asterism in our sky, not far from Bootes’ brightest star Arcturus. It is very far north on the sky’s dome, which is why Southern Hemisphere observers probably won’t see many (if any) Quadrantid meteors. Most of the meteors simply won’t make it above the horizon for Southern Hemisphere skywatchers. But some might!

In 2003, Peter Jenniskens proposed that this object, 2003 EH1, is the parent body of the Quadrantid meteor shower.

Quadrantid meteors have a mysterious parent object. In 2003, astronomer Peter Jenniskens tentatively identified the parent body of the Quadrantids as the asteroid 2003 EH1. If indeed this body is the Quadrantids parent, then the Quadrantids, like the Geminid meteors, come from a rocky body – not an icy comet. Strange.

In turn, though, 2003 EH1 might be the same object as the comet C/1490 Y1, which was observed by Chinese, Japanese and Korean astronomers 500 years ago.

So the exact story behind the Quadrantids’ parent object remains somewhat mysterious.

Bottom line: The first major meteor shower of 2019, and every year, the Quadrantid meteor shower, will probably be at its best in the hours between midnight and dawn January 4. Fortunately, in 2019, the absence of moonlight means dark skies for this year’s annual Quadrantid meteor shower.

Celebrate 2019 with an EarthSky moon calendar!

from EarthSky http://bit.ly/2s2qBRm

Welcome to 2019!

Image via Mohamed Laaïfat Photographies.

Best New Year’s gift ever! EarthSky moon calendar for 2019

from EarthSky http://bit.ly/2SusguN

Image via Mohamed Laaïfat Photographies.

Best New Year’s gift ever! EarthSky moon calendar for 2019

from EarthSky http://bit.ly/2SusguN