Saturn’s large moon Titan is drifting away 100 times faster than anyone knew

Titan orbiting Saturn, as seen by the Cassini spacecraft on May 12, 2012. Image via NASA/ JPL-Caltech/ Space Science Institute.

Researchers knew Saturn’s moon, Titan, was moving away from its planet, just as Earth’s moon gradually orbits farther from Earth. But – while Titan’s outward drift is still extremely slow – this large moon is now known to be moving away from Saturn 100 times faster than previously thought. That’s according to a June 2020 announcement by scientists in the U.S., France and Italy.

The peer-reviewed findings were published on June 8 in the journal Nature Astronomy.

The rate of Titan’s movement away from Saturn had been thought to be well understood, but as often happens in science, a new discovery has upended that idea. The discovery was made via a new analysis of data from the Cassini spacecraft, which orbited Saturn from 2004 to 2017. The data show Titan moving outward at about 4 inches (11 centimeters) per year.

That might not sound like a lot, but it’s significantly faster than the rate at which our moon drifts away from Earth. Our moon is drifting outward at only about 1.5 inches (3.8 centimeters) each year.

Titan’s surface as seen in infrared via Cassini on November 13, 2015. Titan is completely surrounded by thick haze, but Cassini’s radar penetrated the haze to reveal surface details. Image via NASA/ JPL/ University of Arizona/ University of Idaho.

The researchers reached this conclusion after studying images of stars sent back by Cassini. They mapped the background stars and tracked the position of Titan among them. Those images were then compared to a completely separate dataset, Cassini’s radio science data. Cassini sent radio waves back to Earth during 10 close flybys that the spacecraft conducted of Titan between 2006 and 2016. By examining how the frequency of the radio signals was affected by interactions with its environment in space, the researchers could estimate how Titan’s orbit evolved and changed over the past few billion years. Study coauthor Paolo Tortora, of Italy’s University of Bologna, explained in a statement:

By using two completely different datasets, we obtained results that are in full agreement, and also in agreement with Jim Fuller’s theory, which predicted a much faster migration of Titan.

Why do moons move away from their planets, anyway?

Titan is one of the outer moons of Saturn, orbiting well beyond the main rings and out past Rhea. Image via NASA/ JPL/ Wikipedia.

As a moon orbits a planet, its gravity tugs a bit on the planet – a process called tidal friction – creating strain and a resulting very slight bulge on the planet. On Earth, this bulge happens most noticably in our oceans – called a tidal bulge – and causes the cycle of high and low tides, but planets without oceans can bulge, too. This cyclic process of bulging and then subsequent relaxing creates a lot of energy over a long period of time. Tidal friction, however, also prevents the tidal bulge on Earth from remaining directly beneath the moon; instead it is carried along with the rotation of the Earth. The energy, created by mutual attraction between the moon and the material in the bulge, accelerates the moon slightly in its orbit. This causes the moon to drift a tiny bit farther away from Earth over time.

The new result also has implications for the age of the entire Saturn system. It’s still uncertain just how old Saturn’s rings are, as well as the planet’s moons. Right now, Titan is 759,000 miles (1.2 million kilometers) from Saturn; if the new measurement of the moon’s drift rate is correct, it means that Titan must have once been closer to Saturn than previously understood, and that Titan has migrated to its current position far out from the planet. In other words, Titan must have gone from being an inner moon to being an outer moon.

The new result further implies that the entire Saturn system of moons expanded faster than thought. Valery Lainey, lead author of the new study, formerly a scientist at the Jet Propulsion Laboratory (JPL) and now at the Paris Observatory at PSL University, stated:

This result brings an important new piece of the puzzle for the highly debated question of the age of the Saturn system and how its moons formed.

Artist’s concept of Cassini near Titan. Image via Kevin Gill/ Flickr/ Smithsonian Magazine.

Plus, the findings offer validation for a theory about how planets affect the orbits of their moons. Previous theories have stated that moons farther out from a planet migrate more slowly than moons closer in. The assumption was that the planet’s gravity would have a greater affect on moons that were closer, which sounds logical. But that view came into dispute four years ago, thanks to theoretical astrophysicist Jim Fuller at Caltech. He predicted that outer moons and inner moons should actually migrate at similar rates, because outer moons have a different orbit pattern linked to the “wobble” of a planet. That wobble can sling inner moons outward. Fuller said:

The new measurements imply that these kind of planet-moon interactions can be more prominent than prior expectations and that they can apply to many systems, such as other planetary moon systems, exoplanets – those outside our solar system – and even binary star systems, where stars orbit each other.

Valery Lainey at JPL and the Paris Observatory, lead author of the new study. Image via ResearchGate.

Cassini orbited Saturn for more than 13 years, collecting vast amounts of data and taking thousands of images. The mission ended in September 2017 after the spacecraft finally ran out of fuel. By design, Cassini plummeted into Saturn’s deep, tumultuous clouds to burn up so as to not risk contaminating any of the moons, especially Enceladus or Titan, with any stray microbes from Earth that may have still been onboard. Cassini revolutionized our knowledge about the Saturn system, and as this study shows, there is still much to learn.

Bottom line: New study shows that Titan is moving away from Saturn 100 times faster than first thought.

Source: Resonance locking in giant planets indicated by the rapid orbital expansion of Titan

Via Jet Propulsion Laboratory

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Titan orbiting Saturn, as seen by the Cassini spacecraft on May 12, 2012. Image via NASA/ JPL-Caltech/ Space Science Institute.

Researchers knew Saturn’s moon, Titan, was moving away from its planet, just as Earth’s moon gradually orbits farther from Earth. But – while Titan’s outward drift is still extremely slow – this large moon is now known to be moving away from Saturn 100 times faster than previously thought. That’s according to a June 2020 announcement by scientists in the U.S., France and Italy.

The peer-reviewed findings were published on June 8 in the journal Nature Astronomy.

The rate of Titan’s movement away from Saturn had been thought to be well understood, but as often happens in science, a new discovery has upended that idea. The discovery was made via a new analysis of data from the Cassini spacecraft, which orbited Saturn from 2004 to 2017. The data show Titan moving outward at about 4 inches (11 centimeters) per year.

That might not sound like a lot, but it’s significantly faster than the rate at which our moon drifts away from Earth. Our moon is drifting outward at only about 1.5 inches (3.8 centimeters) each year.

Titan’s surface as seen in infrared via Cassini on November 13, 2015. Titan is completely surrounded by thick haze, but Cassini’s radar penetrated the haze to reveal surface details. Image via NASA/ JPL/ University of Arizona/ University of Idaho.

The researchers reached this conclusion after studying images of stars sent back by Cassini. They mapped the background stars and tracked the position of Titan among them. Those images were then compared to a completely separate dataset, Cassini’s radio science data. Cassini sent radio waves back to Earth during 10 close flybys that the spacecraft conducted of Titan between 2006 and 2016. By examining how the frequency of the radio signals was affected by interactions with its environment in space, the researchers could estimate how Titan’s orbit evolved and changed over the past few billion years. Study coauthor Paolo Tortora, of Italy’s University of Bologna, explained in a statement:

By using two completely different datasets, we obtained results that are in full agreement, and also in agreement with Jim Fuller’s theory, which predicted a much faster migration of Titan.

Why do moons move away from their planets, anyway?

Titan is one of the outer moons of Saturn, orbiting well beyond the main rings and out past Rhea. Image via NASA/ JPL/ Wikipedia.

As a moon orbits a planet, its gravity tugs a bit on the planet – a process called tidal friction – creating strain and a resulting very slight bulge on the planet. On Earth, this bulge happens most noticably in our oceans – called a tidal bulge – and causes the cycle of high and low tides, but planets without oceans can bulge, too. This cyclic process of bulging and then subsequent relaxing creates a lot of energy over a long period of time. Tidal friction, however, also prevents the tidal bulge on Earth from remaining directly beneath the moon; instead it is carried along with the rotation of the Earth. The energy, created by mutual attraction between the moon and the material in the bulge, accelerates the moon slightly in its orbit. This causes the moon to drift a tiny bit farther away from Earth over time.

The new result also has implications for the age of the entire Saturn system. It’s still uncertain just how old Saturn’s rings are, as well as the planet’s moons. Right now, Titan is 759,000 miles (1.2 million kilometers) from Saturn; if the new measurement of the moon’s drift rate is correct, it means that Titan must have once been closer to Saturn than previously understood, and that Titan has migrated to its current position far out from the planet. In other words, Titan must have gone from being an inner moon to being an outer moon.

The new result further implies that the entire Saturn system of moons expanded faster than thought. Valery Lainey, lead author of the new study, formerly a scientist at the Jet Propulsion Laboratory (JPL) and now at the Paris Observatory at PSL University, stated:

This result brings an important new piece of the puzzle for the highly debated question of the age of the Saturn system and how its moons formed.

Artist’s concept of Cassini near Titan. Image via Kevin Gill/ Flickr/ Smithsonian Magazine.

Plus, the findings offer validation for a theory about how planets affect the orbits of their moons. Previous theories have stated that moons farther out from a planet migrate more slowly than moons closer in. The assumption was that the planet’s gravity would have a greater affect on moons that were closer, which sounds logical. But that view came into dispute four years ago, thanks to theoretical astrophysicist Jim Fuller at Caltech. He predicted that outer moons and inner moons should actually migrate at similar rates, because outer moons have a different orbit pattern linked to the “wobble” of a planet. That wobble can sling inner moons outward. Fuller said:

The new measurements imply that these kind of planet-moon interactions can be more prominent than prior expectations and that they can apply to many systems, such as other planetary moon systems, exoplanets – those outside our solar system – and even binary star systems, where stars orbit each other.

Valery Lainey at JPL and the Paris Observatory, lead author of the new study. Image via ResearchGate.

Cassini orbited Saturn for more than 13 years, collecting vast amounts of data and taking thousands of images. The mission ended in September 2017 after the spacecraft finally ran out of fuel. By design, Cassini plummeted into Saturn’s deep, tumultuous clouds to burn up so as to not risk contaminating any of the moons, especially Enceladus or Titan, with any stray microbes from Earth that may have still been onboard. Cassini revolutionized our knowledge about the Saturn system, and as this study shows, there is still much to learn.

Bottom line: New study shows that Titan is moving away from Saturn 100 times faster than first thought.

Source: Resonance locking in giant planets indicated by the rapid orbital expansion of Titan

Via Jet Propulsion Laboratory

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The secrets of night-shining clouds

View at EarthSky Community Photos. | Noctilucent – or night-shining – clouds just after midnight on June 16, 2020. Nature photographer Ruslan Merzlyakov in Limfjord, Denmark, said these clouds were: ” … disturbed by the high-altitude turbulence.” Thank you, Ruslan!

Every year – from May through August in the Northern Hemisphere, and from November through February in the Southern Hemisphere – people at high latitudes report seeing noctilucent or night-shining clouds. We read at SpaceWeather.com this weekend that these beautiful clouds have now descended to their lowest latitude of the 2020 season so far: +44 degrees north in Bend, Oregon. Bend resident Roy Reynolds, who photographed the glowing clouds on June 18, 2020, told SpaceWeather:

I woke up at 3:30 a.m. to a very bright sky shining through the shades. I got up to take a look and was surprised to find noctilucent clouds. I live in Bend Oregon and since living here (18 years) have seen this only two other times. Beautiful.

Noctilucent clouds typically descend even lower after the summer solstice, according to Tony Phillips of SpaceWeather.com. If you’re at a northerly latitude, now is a good time to watch for them!

View at EarthSky Community Photos. | Menno van der Haven reported from Waddinxveen, the Netherlands, on June 21, 2020: “Last night, the ‘evening view’ of noctilucent clouds in the northwest was quite small and weak. However, if you use a zoom lens and overexpose with a certain amount, you often see some pretty curls. One in particular resembled a corkscrew and also behaved like this …” Thank you, Meeno!

When the sun is below the ground horizon but visible from the high altitude of noctilucent clouds, sunlight illuminates these clouds, causing them to glow in the dark night sky. Illustration via NASA.

What are noctilucent clouds? Noctilucent clouds form in the highest reaches of the atmosphere – the mesosphere – as much as 50 miles (80 km) above the Earth’s surface. They’re thought to be made of ice crystals that form on fine dust particles from meteors. They can only form when temperatures are incredibly low and when there’s water available to form ice crystals.

Why do these clouds – which require such cold temperatures – form in the summer? It’s because of the dynamics of the atmosphere. You actually get the coldest temperatures of the year near the poles in summer at that height in the mesosphere.

Here’s how it works: during summer, air close to the ground gets heated and rises. Since atmospheric pressure decreases with altitude, the rising air expands. When the air expands, it also cools down. This, along with other processes in the upper atmosphere, drives the air even higher causing it to cool even more. As a result, temperatures in the mesosphere can plunge to as low as -210 degrees Fahrenheit (-134 degrees Celsius).

In the Northern Hemisphere, the mesosphere often reaches these temperatures by mid-May, in most years.

Since the clouds are so sensitive to the atmospheric temperatures, they can act as a proxy for information about the wind circulation that causes these temperatures. First of all, they can tell scientists that the circulation exists, and also tell us something about the strength of the circulation.

How can I see noctilucent clouds? If you want to see the clouds, what steps should you take? Remember, you have to be at a relatively high latitude on Earth to see them: typically between about 45 degrees and 60 degrees north or south latitude, although the clouds can sometimes be seen at lower latitudes, particularly following the solstices.

For best results, look for these clouds from about May through August in the Northern Hemisphere, and from November through February in the Southern Hemisphere.

Noctilucent clouds are primarily visible when the sun is just below the horizon, say, from about 90 minutes to about two hours after sunset or before sunrise. At such times, when the sun is below the ground horizon but visible from the high altitude of noctilucent clouds, sunlight illuminates these clouds, causing them to glow in the dark night sky.

View at EarthSky Community Photos. | Marek Nikodem captured this image at 11:59 p.m. on June 16, 2020, near Szubin, Poland. He wrote: “The noctilucent clouds were visible all night, from dusk to dawn.”

Scientists studying these clouds have included those from NASA’s Aeronomy of Ice in the Mesosphere (AIM) satellite. This satellite, launched in 2007, has observed noctilucent clouds using several onboard instruments to collect information such as temperature, atmospheric gases, ice crystal size and changes in the clouds, as well as the amount of meteoric space dust that enters the atmosphere. You can find out what they are learning at NASA’s AIM page.

Noctilucent clouds can be seen from space, too. Astronauts in the International Space Station (ISS) took this photo on January 5, 2013, when ISS was over the Pacific Ocean south of French Polynesia. Below the brightly-lit noctilucent clouds, across the center of the image, the pale orange band is the stratosphere. Image via NASA.

Bottom line: Noctilucent or night-shining clouds are seen during summer in Earth’s high-latitude regions. They form in the highest reaches of the atmosphere – the mesosphere – as much as 50 miles (80 km) above the surface.

Visit SpaceWeather’s RealTime Noctilucent Cloud Gallery

Visit the Facebook page Noctilucent Clouds Around the World

from EarthSky https://ift.tt/3dhviw0

View at EarthSky Community Photos. | Noctilucent – or night-shining – clouds just after midnight on June 16, 2020. Nature photographer Ruslan Merzlyakov in Limfjord, Denmark, said these clouds were: ” … disturbed by the high-altitude turbulence.” Thank you, Ruslan!

Every year – from May through August in the Northern Hemisphere, and from November through February in the Southern Hemisphere – people at high latitudes report seeing noctilucent or night-shining clouds. We read at SpaceWeather.com this weekend that these beautiful clouds have now descended to their lowest latitude of the 2020 season so far: +44 degrees north in Bend, Oregon. Bend resident Roy Reynolds, who photographed the glowing clouds on June 18, 2020, told SpaceWeather:

I woke up at 3:30 a.m. to a very bright sky shining through the shades. I got up to take a look and was surprised to find noctilucent clouds. I live in Bend Oregon and since living here (18 years) have seen this only two other times. Beautiful.

Noctilucent clouds typically descend even lower after the summer solstice, according to Tony Phillips of SpaceWeather.com. If you’re at a northerly latitude, now is a good time to watch for them!

View at EarthSky Community Photos. | Menno van der Haven reported from Waddinxveen, the Netherlands, on June 21, 2020: “Last night, the ‘evening view’ of noctilucent clouds in the northwest was quite small and weak. However, if you use a zoom lens and overexpose with a certain amount, you often see some pretty curls. One in particular resembled a corkscrew and also behaved like this …” Thank you, Meeno!

When the sun is below the ground horizon but visible from the high altitude of noctilucent clouds, sunlight illuminates these clouds, causing them to glow in the dark night sky. Illustration via NASA.

What are noctilucent clouds? Noctilucent clouds form in the highest reaches of the atmosphere – the mesosphere – as much as 50 miles (80 km) above the Earth’s surface. They’re thought to be made of ice crystals that form on fine dust particles from meteors. They can only form when temperatures are incredibly low and when there’s water available to form ice crystals.

Why do these clouds – which require such cold temperatures – form in the summer? It’s because of the dynamics of the atmosphere. You actually get the coldest temperatures of the year near the poles in summer at that height in the mesosphere.

Here’s how it works: during summer, air close to the ground gets heated and rises. Since atmospheric pressure decreases with altitude, the rising air expands. When the air expands, it also cools down. This, along with other processes in the upper atmosphere, drives the air even higher causing it to cool even more. As a result, temperatures in the mesosphere can plunge to as low as -210 degrees Fahrenheit (-134 degrees Celsius).

In the Northern Hemisphere, the mesosphere often reaches these temperatures by mid-May, in most years.

Since the clouds are so sensitive to the atmospheric temperatures, they can act as a proxy for information about the wind circulation that causes these temperatures. First of all, they can tell scientists that the circulation exists, and also tell us something about the strength of the circulation.

How can I see noctilucent clouds? If you want to see the clouds, what steps should you take? Remember, you have to be at a relatively high latitude on Earth to see them: typically between about 45 degrees and 60 degrees north or south latitude, although the clouds can sometimes be seen at lower latitudes, particularly following the solstices.

For best results, look for these clouds from about May through August in the Northern Hemisphere, and from November through February in the Southern Hemisphere.

Noctilucent clouds are primarily visible when the sun is just below the horizon, say, from about 90 minutes to about two hours after sunset or before sunrise. At such times, when the sun is below the ground horizon but visible from the high altitude of noctilucent clouds, sunlight illuminates these clouds, causing them to glow in the dark night sky.

View at EarthSky Community Photos. | Marek Nikodem captured this image at 11:59 p.m. on June 16, 2020, near Szubin, Poland. He wrote: “The noctilucent clouds were visible all night, from dusk to dawn.”

Scientists studying these clouds have included those from NASA’s Aeronomy of Ice in the Mesosphere (AIM) satellite. This satellite, launched in 2007, has observed noctilucent clouds using several onboard instruments to collect information such as temperature, atmospheric gases, ice crystal size and changes in the clouds, as well as the amount of meteoric space dust that enters the atmosphere. You can find out what they are learning at NASA’s AIM page.

Noctilucent clouds can be seen from space, too. Astronauts in the International Space Station (ISS) took this photo on January 5, 2013, when ISS was over the Pacific Ocean south of French Polynesia. Below the brightly-lit noctilucent clouds, across the center of the image, the pale orange band is the stratosphere. Image via NASA.

Bottom line: Noctilucent or night-shining clouds are seen during summer in Earth’s high-latitude regions. They form in the highest reaches of the atmosphere – the mesosphere – as much as 50 miles (80 km) above the surface.

Visit SpaceWeather’s RealTime Noctilucent Cloud Gallery

Visit the Facebook page Noctilucent Clouds Around the World

from EarthSky https://ift.tt/3dhviw0

Emperor penguins are good dads

Emperor penguin dad keeps his egg warm while waiting for his chick to hatch. Image via Tony Bojkovski/ Australian Antarctic Division.

We know there are some awesome dads out there among you humans. But the nominees for best dad must surely include emperor penguin males, who go to extraordinary extremes for their offspring, enduring bitter cold and darkness during winter on Earth’s coldest continent, Antarctica. It’s winter in Antarctica now. If you could visit, you’d find emperor penguin males gathered in colonies near the coast. They’re tightly huddled together to stay warm in temperatures that can dip as low as -40 degrees F (-40 degrees C), with winds as strong as 90 miles per hour (144 km/ hour). For the next two months, these devoted dads will each incubate a single egg that holds his offspring. Each dad will also care for his chick when it first hatches. Penguin dads do all this while surviving only on fat reserves from the previous summer.

A diagram of the emperor penguin’s breeding schedule. Image via Zina Deretsky/ NSF/ Wikimedia Commons.

Emperor penguins huddle during a blizzard. Image via Frederique Olivier/ Australian Antarctic Division.

For much of the summer, male and female emperor penguins are at sea, feeding on fish, squid, and krill. For the males, it’s an opportunity to accumulate fat reserves they’ll need to survive in winter.

In April, autumn in the Southern Hemisphere, adult emperor penguins begin congregating at their respective nesting areas, traveling inland as much as 30 to 75 miles (50 to 120 kilometers) from the pack ice.

Following courtship displays, the birds form pairs and mate. In May and early June, the female lays a single egg. The egg is pear-shaped with a pale greenish-white tint, almost 5 inches long and 3 inches wide (12 and 8 cm, respectively). The female penguin passes the egg to her mate, then heads back to sea. She’ll be back in two months to continue her parental duties.

Until then, the males are on their own for winter in Antarctica. Their dense insulating feathers and fat accumulations, however, aren’t enough to keep them alive. To conserve heat, the emperor penguin males huddle close together. Each colony varies in size, and could number several hundred birds. They take turns moving from the edge of the colony, which is colder, to the warmer center.

The egg, meanwhile, is snugly tucked away in dad’s brood pouch, resting on his feet. If all goes well, the chick will hatch in 65 to 75 days. Hatching will likely happen a few days before mom returns. During this time, the chick, weighing just 11 ounces (312 grams) with only a thin layer of down feathers, is completely dependent on dad for warmth and protection. Until mom returns to start feeding the chick, he also provides his offspring with what’s called crop milk, a high fat and protein secretion.

Mom returns to the colony, sometime between mid-July and early August, after spending the last two months feeding at sea. She takes over caring for the chick while dad, having not eaten for about 120 days, heads to the ocean to start feeding. By now, he has dropped in weight to around 50 pounds (23 kilograms) from his summer weight of about 84 pounds (38 kilograms).

Dad will spend about three to four weeks feeding at sea, then return to his mate. From then on, the pair takes turns caring for their little one, keeping it warm and feeding it regurgitated krill, fish, and squid.

An emperor penguin pair with their chick. Image via Gary Miller / Australian Antarctic Division.

About 50 days after hatching, the colony’s chicks, now sporting a thick downy coat, are corralled together for warmth and protection in what’s called a crèche – that’s emperor penguin daycare where the chicks wait for their parents to return from the sea to feed them.

In early November, as spring yields to summer in Antarctica, the chicks undergo a two-month moult, replacing their downy chick feathers with juvenile plumage that will enable them to swim.

By December and January, the chicks are nearly as big as their parents. At this point, mom and dad have done their job and will stop feeding the kids. The youngsters will then venture to sea to start foraging on their own. In about three to four years, they will be old enough to start breeding.

An emperor penguin chick. Image via Robin Mundy/ Australian Antarctic Division.

Bottom line: Male emperor penguins are some of the best dads in the world. They incubate their eggs for over two months in the frigid Antarctic winter.

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Emperor penguin dad keeps his egg warm while waiting for his chick to hatch. Image via Tony Bojkovski/ Australian Antarctic Division.

We know there are some awesome dads out there among you humans. But the nominees for best dad must surely include emperor penguin males, who go to extraordinary extremes for their offspring, enduring bitter cold and darkness during winter on Earth’s coldest continent, Antarctica. It’s winter in Antarctica now. If you could visit, you’d find emperor penguin males gathered in colonies near the coast. They’re tightly huddled together to stay warm in temperatures that can dip as low as -40 degrees F (-40 degrees C), with winds as strong as 90 miles per hour (144 km/ hour). For the next two months, these devoted dads will each incubate a single egg that holds his offspring. Each dad will also care for his chick when it first hatches. Penguin dads do all this while surviving only on fat reserves from the previous summer.

A diagram of the emperor penguin’s breeding schedule. Image via Zina Deretsky/ NSF/ Wikimedia Commons.

Emperor penguins huddle during a blizzard. Image via Frederique Olivier/ Australian Antarctic Division.

For much of the summer, male and female emperor penguins are at sea, feeding on fish, squid, and krill. For the males, it’s an opportunity to accumulate fat reserves they’ll need to survive in winter.

In April, autumn in the Southern Hemisphere, adult emperor penguins begin congregating at their respective nesting areas, traveling inland as much as 30 to 75 miles (50 to 120 kilometers) from the pack ice.

Following courtship displays, the birds form pairs and mate. In May and early June, the female lays a single egg. The egg is pear-shaped with a pale greenish-white tint, almost 5 inches long and 3 inches wide (12 and 8 cm, respectively). The female penguin passes the egg to her mate, then heads back to sea. She’ll be back in two months to continue her parental duties.

Until then, the males are on their own for winter in Antarctica. Their dense insulating feathers and fat accumulations, however, aren’t enough to keep them alive. To conserve heat, the emperor penguin males huddle close together. Each colony varies in size, and could number several hundred birds. They take turns moving from the edge of the colony, which is colder, to the warmer center.

The egg, meanwhile, is snugly tucked away in dad’s brood pouch, resting on his feet. If all goes well, the chick will hatch in 65 to 75 days. Hatching will likely happen a few days before mom returns. During this time, the chick, weighing just 11 ounces (312 grams) with only a thin layer of down feathers, is completely dependent on dad for warmth and protection. Until mom returns to start feeding the chick, he also provides his offspring with what’s called crop milk, a high fat and protein secretion.

Mom returns to the colony, sometime between mid-July and early August, after spending the last two months feeding at sea. She takes over caring for the chick while dad, having not eaten for about 120 days, heads to the ocean to start feeding. By now, he has dropped in weight to around 50 pounds (23 kilograms) from his summer weight of about 84 pounds (38 kilograms).

Dad will spend about three to four weeks feeding at sea, then return to his mate. From then on, the pair takes turns caring for their little one, keeping it warm and feeding it regurgitated krill, fish, and squid.

An emperor penguin pair with their chick. Image via Gary Miller / Australian Antarctic Division.

About 50 days after hatching, the colony’s chicks, now sporting a thick downy coat, are corralled together for warmth and protection in what’s called a crèche – that’s emperor penguin daycare where the chicks wait for their parents to return from the sea to feed them.

In early November, as spring yields to summer in Antarctica, the chicks undergo a two-month moult, replacing their downy chick feathers with juvenile plumage that will enable them to swim.

By December and January, the chicks are nearly as big as their parents. At this point, mom and dad have done their job and will stop feeding the kids. The youngsters will then venture to sea to start foraging on their own. In about three to four years, they will be old enough to start breeding.

An emperor penguin chick. Image via Robin Mundy/ Australian Antarctic Division.

Bottom line: Male emperor penguins are some of the best dads in the world. They incubate their eggs for over two months in the frigid Antarctic winter.

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It’s summer. What’s noon to you?

Image via ©iStockphoto.com/ KavalenkavaVolha/ timeanddate

When is it noon for you? That’s not as easy a question to answer as you might think! What do you mean by noon? Do you define it by your clock or wristwatch? Or the gnawing in your stomach that says it’s time for lunch? Well, you might want to think again!

We in the Northern Hemisphere typically say the first day of summer comes at the June solstice, which, in 2020, fell on June 20. But – no matter what day it is – when noon occurs depends in part on your location and in part on your definition of noon. On the day of a June solstice, noontime shadows are just a hair shorter than the day before. That’s because, at the June solstice, Earth’s Northern Hemisphere is tilted most sunward for the year, and the sun rises highest in our Northern Hemisphere sky, yielding the year’s shortest midday shadows.

Photo by EarthSky Facebook friend Muhammad Mohsin Jameel. He wrote: “Shortest shadows at noon, summer solstice — in Islamabad, Pakistan!”

Notice that I said midday, rather than just noon. Usually when most of us say noon, we mean 12 p.m. on the clock. But that may not be what astronomers mean by noon.

Around the time of the June solstice, shadows are shortest when the sun is due south in the sky. We say that the sun is crossing the meridian. But the sun’s meridian crossing rarely occurs at exactly straight-up noon, according to the clock. The time at which the sun crosses the meridian used to be called high noon because that is when the sun is highest in the sky. Today we astronomers sometimes refer to it as transit time or local solar noon.

I have assigned my students a project in which they compare the height of the sun at local solar noon to that in another location in New Mexico. This simulates an observation by Eratosthenes more than 2,000 years ago, through which he obtained the first accurate measurement of the size of the Earth.

You can construct a simple device called a gnomon (pronounced NO-mun) or shadow stick to calculate how high the sun is, with simple trigonometry. Just measure the height of the gnomon (H) and the length of the shadow (L) at local solar noon. Then the angular height of the sun is the arctangent of H/L. For accuracy, the gnomon must be very straight, the ground level, and the measurements precise. Here in Denver, it will be about 73.75 degrees high. How high is it where you live?

But before you can make the measurement, you need to know when local solar noon occurs where you are located. Before the invention of the telegraph in the 19th century, every locality defined noon by the time when the sun crossed the meridian. Because of geographical location, when the sun crosses the meridian as seen in Denver, in Grand Junction (about 180 miles to the west) the sun hasn’t reached the meridian yet, and won’t for another 14 minutes or so. It takes about 14 minutes for the Earth to turn far enough to bring the sun to the meridian in Grand Junction after it passes the meridian in Denver.

At a time when the fastest form of communication was a stagecoach or the Pony Express, this difference in time did not matter. But when near-instantaneous communication became available with the telegraph, people gradually realized that a standardization of time was necessary. Thus the concept of time zones was developed in 1884, but not adopted officially in the U.S. until 1918.

But even considering time zones, the actual time of transit varies through the year because of the Earth’s varying speed in its orbit around the sun. At times the planet has to turn a bit more from one transit to the next, and at times it needs to turn a bit less. This is because the change in Earth’s speed (due to varying distance to the sun through the year) causes the sun’s apparent motion across the sky to change. There is also a variation due to the tilt of the Earth and how that affects the sun’s apparent motion in the sky. That means that the real sun (which crosses the meridian at local solar noon) is as much as 16 minutes faster or slower than the steady but fictitious mean sun that defines clock-time noon for the various time zones.

And then of course there is the complication of “Daylight Saving Time,” which really saves nothing but merely offsets the clocks by an hour.

Now you can make all the calculations to figure out transit time or local solar noon for yourself, but you don’t need to go to the trouble. Just go to the U.S. Naval Observatory website and have it calculate it for you.

Here are some examples of typical transit times, or local solar noons, for June 21, as calculated by the Naval Observatory website:

Eastern Time Zone		Central Time Zone		Mountain Time Zone		Pacific Time Zone
New York	12:57 p.m	Chicago	12:53 p.m.	Denver	1:02 p.m.	Los Angeles	12:55 p.m.
Miami	1:23 p.m.	Little Rock	1:11 p.m.	Albuquerque	1:08 p.m.	Seattle	1:11 p.m.
Detroit	1:34 p.m.	Kansas City (KS)	1:21 p.m.	Salt Lake City	1:29 p.m.	San Francisco	1:12 p.m.
Atlanta	1:39 p.m.	Houston	1:23 p.m.	Phoenix	12:30 p.m. *	Portland	1:12 p.m.

* Note that Phoenix is on Standard, not Daylight, Time. Also note that the exact moment of the summer solstice is not related to the time of local solar noon.

Oh, and by the way, if you’re out in the sun – contemplating the passage of the sun and the time of noon for you – don’t forget your sunscreen.

Bottom line: What is the definition of noon? An exploration of how astronomers think about noontime.

from EarthSky https://ift.tt/2V4icMk

Image via ©iStockphoto.com/ KavalenkavaVolha/ timeanddate

When is it noon for you? That’s not as easy a question to answer as you might think! What do you mean by noon? Do you define it by your clock or wristwatch? Or the gnawing in your stomach that says it’s time for lunch? Well, you might want to think again!

We in the Northern Hemisphere typically say the first day of summer comes at the June solstice, which, in 2020, fell on June 20. But – no matter what day it is – when noon occurs depends in part on your location and in part on your definition of noon. On the day of a June solstice, noontime shadows are just a hair shorter than the day before. That’s because, at the June solstice, Earth’s Northern Hemisphere is tilted most sunward for the year, and the sun rises highest in our Northern Hemisphere sky, yielding the year’s shortest midday shadows.

Photo by EarthSky Facebook friend Muhammad Mohsin Jameel. He wrote: “Shortest shadows at noon, summer solstice — in Islamabad, Pakistan!”

Notice that I said midday, rather than just noon. Usually when most of us say noon, we mean 12 p.m. on the clock. But that may not be what astronomers mean by noon.

Around the time of the June solstice, shadows are shortest when the sun is due south in the sky. We say that the sun is crossing the meridian. But the sun’s meridian crossing rarely occurs at exactly straight-up noon, according to the clock. The time at which the sun crosses the meridian used to be called high noon because that is when the sun is highest in the sky. Today we astronomers sometimes refer to it as transit time or local solar noon.

I have assigned my students a project in which they compare the height of the sun at local solar noon to that in another location in New Mexico. This simulates an observation by Eratosthenes more than 2,000 years ago, through which he obtained the first accurate measurement of the size of the Earth.

You can construct a simple device called a gnomon (pronounced NO-mun) or shadow stick to calculate how high the sun is, with simple trigonometry. Just measure the height of the gnomon (H) and the length of the shadow (L) at local solar noon. Then the angular height of the sun is the arctangent of H/L. For accuracy, the gnomon must be very straight, the ground level, and the measurements precise. Here in Denver, it will be about 73.75 degrees high. How high is it where you live?

But before you can make the measurement, you need to know when local solar noon occurs where you are located. Before the invention of the telegraph in the 19th century, every locality defined noon by the time when the sun crossed the meridian. Because of geographical location, when the sun crosses the meridian as seen in Denver, in Grand Junction (about 180 miles to the west) the sun hasn’t reached the meridian yet, and won’t for another 14 minutes or so. It takes about 14 minutes for the Earth to turn far enough to bring the sun to the meridian in Grand Junction after it passes the meridian in Denver.

At a time when the fastest form of communication was a stagecoach or the Pony Express, this difference in time did not matter. But when near-instantaneous communication became available with the telegraph, people gradually realized that a standardization of time was necessary. Thus the concept of time zones was developed in 1884, but not adopted officially in the U.S. until 1918.

But even considering time zones, the actual time of transit varies through the year because of the Earth’s varying speed in its orbit around the sun. At times the planet has to turn a bit more from one transit to the next, and at times it needs to turn a bit less. This is because the change in Earth’s speed (due to varying distance to the sun through the year) causes the sun’s apparent motion across the sky to change. There is also a variation due to the tilt of the Earth and how that affects the sun’s apparent motion in the sky. That means that the real sun (which crosses the meridian at local solar noon) is as much as 16 minutes faster or slower than the steady but fictitious mean sun that defines clock-time noon for the various time zones.

And then of course there is the complication of “Daylight Saving Time,” which really saves nothing but merely offsets the clocks by an hour.

Now you can make all the calculations to figure out transit time or local solar noon for yourself, but you don’t need to go to the trouble. Just go to the U.S. Naval Observatory website and have it calculate it for you.

Here are some examples of typical transit times, or local solar noons, for June 21, as calculated by the Naval Observatory website:

Eastern Time Zone		Central Time Zone		Mountain Time Zone		Pacific Time Zone
New York	12:57 p.m	Chicago	12:53 p.m.	Denver	1:02 p.m.	Los Angeles	12:55 p.m.
Miami	1:23 p.m.	Little Rock	1:11 p.m.	Albuquerque	1:08 p.m.	Seattle	1:11 p.m.
Detroit	1:34 p.m.	Kansas City (KS)	1:21 p.m.	Salt Lake City	1:29 p.m.	San Francisco	1:12 p.m.
Atlanta	1:39 p.m.	Houston	1:23 p.m.	Phoenix	12:30 p.m. *	Portland	1:12 p.m.

* Note that Phoenix is on Standard, not Daylight, Time. Also note that the exact moment of the summer solstice is not related to the time of local solar noon.

Oh, and by the way, if you’re out in the sun – contemplating the passage of the sun and the time of noon for you – don’t forget your sunscreen.

Bottom line: What is the definition of noon? An exploration of how astronomers think about noontime.

from EarthSky https://ift.tt/2V4icMk

Solstice sun near Taurus-Gemini border

At the June 20, 2020, solstice, the sun is in front of the constellation Taurus the Bull. On June 21, at around 09:00 UTC, the sun moves out of the constellation Taurus and into the constellation Gemini the Twins. In other words, the sun on the June solstice shines very close to the Taurus-Gemini border.

Relative to the backdrop stars of the zodiac, the sun on the solstice always appears a tiny bit westward of the previous year’s solstice sun.

As seen from Earth, the sun travels in front of the constellation Gemini the Twins from June 22, 2019 at around 03:00 UTC, until July 21 at about 07:00 UTC. Translate UTC to your time. The solstice point is at the intersection of 6h with the ecliptic.

Thirty-one years ago, in the year 1989, the sun was in front of the constellation Gemini on the June solstice. Then in the following year, in 1990, the June solstice sun shone in front of the constellation Taurus, the constellation to the immediate west of Gemini. The sun on the June solstice will continue to shine in front of Taurus until the year 4609, when the June solstice sun will finally move into the constellation Aries, the constellation to the immediate west of Taurus.

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Sign versus constellation

Please keep in mind that we’re talking about constellations – not astrological signs – of the zodiac.

By definition, the sun occupies the first point of (the sign) Cancer on the June solstice, irrespective of which constellation backdrops the sun at this time. Also, the sun reaches the first point of (the sign) Leo when it resides 30 degrees east of the June solstice point along the ecliptic – regardless of which constellation backdrops the sun.

Signs are fixed relative to the solstice and equinox points. On the other hand, the solstice and equinox points slowly but surely move westward relative to the zodiacal constellations.

The solstice and equinox points go full circle through the constellations of the zodiac in about 26,000 years.

Bottom line: On June 21, 2020, at around 09:00 UTC, the sun moves out of the constellation Taurus the Bull and into Gemini the Twins.

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from EarthSky https://ift.tt/2NjkC5j

At the June 20, 2020, solstice, the sun is in front of the constellation Taurus the Bull. On June 21, at around 09:00 UTC, the sun moves out of the constellation Taurus and into the constellation Gemini the Twins. In other words, the sun on the June solstice shines very close to the Taurus-Gemini border.

Relative to the backdrop stars of the zodiac, the sun on the solstice always appears a tiny bit westward of the previous year’s solstice sun.

As seen from Earth, the sun travels in front of the constellation Gemini the Twins from June 22, 2019 at around 03:00 UTC, until July 21 at about 07:00 UTC. Translate UTC to your time. The solstice point is at the intersection of 6h with the ecliptic.

Thirty-one years ago, in the year 1989, the sun was in front of the constellation Gemini on the June solstice. Then in the following year, in 1990, the June solstice sun shone in front of the constellation Taurus, the constellation to the immediate west of Gemini. The sun on the June solstice will continue to shine in front of Taurus until the year 4609, when the June solstice sun will finally move into the constellation Aries, the constellation to the immediate west of Taurus.

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

Sign versus constellation

Please keep in mind that we’re talking about constellations – not astrological signs – of the zodiac.

By definition, the sun occupies the first point of (the sign) Cancer on the June solstice, irrespective of which constellation backdrops the sun at this time. Also, the sun reaches the first point of (the sign) Leo when it resides 30 degrees east of the June solstice point along the ecliptic – regardless of which constellation backdrops the sun.

Signs are fixed relative to the solstice and equinox points. On the other hand, the solstice and equinox points slowly but surely move westward relative to the zodiacal constellations.

The solstice and equinox points go full circle through the constellations of the zodiac in about 26,000 years.

Bottom line: On June 21, 2020, at around 09:00 UTC, the sun moves out of the constellation Taurus the Bull and into Gemini the Twins.

EarthSky astronomy kits are perfect for beginners. Order today from the EarthSky store

Donate: Your support means the world to us

from EarthSky https://ift.tt/2NjkC5j

June’s old moon and Venus

View at EarthSky Community Photos. | Isn’t this the coolest image ever? No, it’s not 2 moons. The larger one is Earth’s moon, and the smaller one is Venus! Alex Conu in Oslo, Norway caught this image of the very close conjunction between the planet Venus and the moon in daylight on June 19, 2020, when both worlds were in a thin crescent phase. A few minutes after this photo was taken, Venus was occulted – or covered over – by the moon. Thank you, Alex!

The brightest planet Venus was prominent in the west after sunset in early 2020, through about late May. On June 3, Venus went between us and the sun in what’s called an inferior conjunction for this inner planet. Now Venus is back in the morning sky – visible from around the world – very near the glare of these far-northern sunrises we’ve having around this solstice-time.

Those with telescopes know that Venus is now visible in a crescent phase. That’s because its lighted face, or day side, is mostly facing away from us now.

The photos on this page are from June 19, 2020, when the old moon – a waning crescent visible in the east before sunup – swept past Venus. Thanks to these two photographers and to all those who contributed to EarthSky Community Photos!

See photos from May and early June: Crescent Venus in the evening sky

View at EarthSky Community Photos. | Donald Gargano also caught the moon and Venus on June 19, 2020, at Jenness Beach in Rye, New Hampshire. This photo shows how you would have seen the pair with the eye alone in a sky brightly lit with morning twilight … if you’d been on this glorious beach! Thank you, Donald.

Bottom line: The brightest planet Venus is back in the east before sunup! It’s very bright, visible near the sunrise, in very bright twilight. Here are two beautiful photos of the very old moon on June 19 – a waning crescent seen in the east shortly before sunrise – near Venus.

from EarthSky https://ift.tt/2AVBVH1

View at EarthSky Community Photos. | Isn’t this the coolest image ever? No, it’s not 2 moons. The larger one is Earth’s moon, and the smaller one is Venus! Alex Conu in Oslo, Norway caught this image of the very close conjunction between the planet Venus and the moon in daylight on June 19, 2020, when both worlds were in a thin crescent phase. A few minutes after this photo was taken, Venus was occulted – or covered over – by the moon. Thank you, Alex!

The brightest planet Venus was prominent in the west after sunset in early 2020, through about late May. On June 3, Venus went between us and the sun in what’s called an inferior conjunction for this inner planet. Now Venus is back in the morning sky – visible from around the world – very near the glare of these far-northern sunrises we’ve having around this solstice-time.

Those with telescopes know that Venus is now visible in a crescent phase. That’s because its lighted face, or day side, is mostly facing away from us now.

The photos on this page are from June 19, 2020, when the old moon – a waning crescent visible in the east before sunup – swept past Venus. Thanks to these two photographers and to all those who contributed to EarthSky Community Photos!

See photos from May and early June: Crescent Venus in the evening sky

View at EarthSky Community Photos. | Donald Gargano also caught the moon and Venus on June 19, 2020, at Jenness Beach in Rye, New Hampshire. This photo shows how you would have seen the pair with the eye alone in a sky brightly lit with morning twilight … if you’d been on this glorious beach! Thank you, Donald.

Bottom line: The brightest planet Venus is back in the east before sunup! It’s very bright, visible near the sunrise, in very bright twilight. Here are two beautiful photos of the very old moon on June 19 – a waning crescent seen in the east shortly before sunrise – near Venus.

from EarthSky https://ift.tt/2AVBVH1

News digest – targeted ‘lava lamp’ treatment, skin cancer biopsies and the iKnife

With news about the coronavirus pandemic developing daily, we want to make sure everyone affected by cancer gets the information they need during this time. 

We’re pulling together the latest government and NHS health updates from across the UK in a separate blog post, which we’re updating regularly. 

‘Lavalamp’ effect could make cancer drugs more powerful

A new study published in Science has revealed how drug molecules are organised when they enter a cell, and how this information could be used to make certain drugs hit their targets more effectively. Research found that cancer drug compounds become concentrated in certain spots within cells – like blobs in a lava lamp. Whilst scientists hope that a better understanding of this phenomenon could lead to more targeted cancer treatments, others think that other mechanisms should be explored. Find out more at Nature.  

Swansea skin cancer patients receive pioneering procedure

Skin cancer patients in Swansea have become first in the world to receive complex biopsies while awake. Sentinel lymph node biopsies allow doctors to detect whether melanoma has spread in skin cancer patients, but the procedure was suspended due to Covid-19 restrictions on general anaesthetic. A team of plastic surgeons and anaesthetists at Sancta Maria Hospital are now the first to carry out the procedure without anaesthetic. So far nine patients have had the test. More on this at BBC.

Scientist uncover new mechanism driving colorectal cancer

MedicalXpress reports on a collaborative study that has revealed a new mechanism causing colorectal cancer. Research by VIB-UGent Center for Inflammation Research and Ghent University found that abnormal expression of the protein Zeb2 could allow harmful bacteria into the intestinal wall, causing inflammation and driving cancer progression. Scientists have now demonstrated how manipulating the immune system could prevent this development and potentially lead to new cancer treatments.  

Searching for novel connections in cancer metabolism

Dr George Poulogiannis is one of our scientists investigating the relationship between cellular metabolism, cancer and diet. In our blog post, we spoke to him about how his team have been investigating connections in metabolism by utilising a unique tool known as the iKnife, used in cancer surgery, in order to open the door to a better understanding of individual cancers. Whilst the team have uncovered new features of breast cancer biology linked to metabolism and diet, and have shown that a dietary fat restriction plays a major role in therapy response, some headlines were quick to jump to a ‘potential cancer cure’.  

And finally… 

A technique known as a liquid biopsy is allowing doctors to find out more about a patient’s cancer without the need for surgery. The technique analyses a patient’s blood, monitoring the DNA tumours release into the blood stream. By analysing the individual genetic makeup of a tumour, liquid biopsies can focus on a specific set of mutations and use them as a starting point to monitor the progression of cancer. Find the full story on our blog. 

Scarlett Sangster is a writer for PA Media Group

from Cancer Research UK – Science blog https://ift.tt/37WeRUZ

With news about the coronavirus pandemic developing daily, we want to make sure everyone affected by cancer gets the information they need during this time. 

We’re pulling together the latest government and NHS health updates from across the UK in a separate blog post, which we’re updating regularly. 

‘Lavalamp’ effect could make cancer drugs more powerful

A new study published in Science has revealed how drug molecules are organised when they enter a cell, and how this information could be used to make certain drugs hit their targets more effectively. Research found that cancer drug compounds become concentrated in certain spots within cells – like blobs in a lava lamp. Whilst scientists hope that a better understanding of this phenomenon could lead to more targeted cancer treatments, others think that other mechanisms should be explored. Find out more at Nature.  

Swansea skin cancer patients receive pioneering procedure

Skin cancer patients in Swansea have become first in the world to receive complex biopsies while awake. Sentinel lymph node biopsies allow doctors to detect whether melanoma has spread in skin cancer patients, but the procedure was suspended due to Covid-19 restrictions on general anaesthetic. A team of plastic surgeons and anaesthetists at Sancta Maria Hospital are now the first to carry out the procedure without anaesthetic. So far nine patients have had the test. More on this at BBC.

Scientist uncover new mechanism driving colorectal cancer

MedicalXpress reports on a collaborative study that has revealed a new mechanism causing colorectal cancer. Research by VIB-UGent Center for Inflammation Research and Ghent University found that abnormal expression of the protein Zeb2 could allow harmful bacteria into the intestinal wall, causing inflammation and driving cancer progression. Scientists have now demonstrated how manipulating the immune system could prevent this development and potentially lead to new cancer treatments.  

Searching for novel connections in cancer metabolism

Dr George Poulogiannis is one of our scientists investigating the relationship between cellular metabolism, cancer and diet. In our blog post, we spoke to him about how his team have been investigating connections in metabolism by utilising a unique tool known as the iKnife, used in cancer surgery, in order to open the door to a better understanding of individual cancers. Whilst the team have uncovered new features of breast cancer biology linked to metabolism and diet, and have shown that a dietary fat restriction plays a major role in therapy response, some headlines were quick to jump to a ‘potential cancer cure’.  

And finally… 

A technique known as a liquid biopsy is allowing doctors to find out more about a patient’s cancer without the need for surgery. The technique analyses a patient’s blood, monitoring the DNA tumours release into the blood stream. By analysing the individual genetic makeup of a tumour, liquid biopsies can focus on a specific set of mutations and use them as a starting point to monitor the progression of cancer. Find the full story on our blog. 

Scarlett Sangster is a writer for PA Media Group

from Cancer Research UK – Science blog https://ift.tt/37WeRUZ