More evidence for watery plumes on Europa

Artist’s concept of water vapor plumes on Europa, the smallest of Jupiter’s 4 large Galilean moons. Image via ASA/ ESA/ K. Retherford/ SwRI/ Science.

The huge plumes of water vapor erupting through enormous cracks in the surface of Saturn’s moon Enceladus were quickly found by the Cassini spacecraft after it began orbiting Saturn in 2004. They’re thought to arise from a salty global ocean below the moon’s ice crust. Over the past few years, evidence has been accumulating for watery plumes on Jupiter’s large ocean moon Europa, too. It’s taking longer to put the pieces of the puzzle together, but – although still not definitive – the data for plumes on Europa are beginning to look compelling. They indicate that geyser-like plumes erupt from Europa’s surface, at least occasionally. On May 12, 2020, researchers at the Max Planck Institute for Solar System Research (MPS) in Germany and the European Space Agency (ESA) reported yet more evidence for water plumes on Europa.

The new work supports previous studies that suggested that – although it wasn’t recognized at the time – NASA’s Galileo spacecraft glimpsed one of these plumes during a flyby of Europa in 2000. The researchers published their work in Geophysical Research Letters in late April.

Making the case for plumes on Europa has been a long process, since, from the evidence gathered so far, they are seemingly intermittent. In contrast, the plumes on Enceladus were large and easy to see and, at least at the time, were erupting continuously. MPS scientist Elias Roussos said in a statement:

 However, various theories, models, and sporadic observations suggest that Europa, too, can exhibit plumes.

Jupiter’s ocean moon Europa, as seen by Galileo. This image is a combination of images from 1995 and 1998. Scientists have found yet more evidence for water vapor plumes erupting from its icy surface, most likely originating in the ocean below. Image via NASA/ JPL-Caltech/ SETI Institute.

How did the researchers find further evidence for Europa’s plumes?

They used computer simulations to replicate the data from the Energetic Particles Detector (EPD) onboard Galileo during a flyby of Europa in 2000. EPD recorded the distribution of high-energy protons trapped in Jupiter’s powerful magnetic field, which is 20 times stronger than Earth’s. Europa orbits within that magnetic field. Back in 2000, the detector recorded fewer protons during the flyby than had been expected. At the time, it was thought that Europa itself was blocking the view of the detector.

But now the new study suggests something else. The researchers modeled the movements of protons during the flyby, in an attempt to reproduce the original results from Galileo. But – surprise – they found that the only model that matched the results was one where a water vapor plume was between Europa and the detector.

Composite photos from the Hubble Space Telescope and the Galileo spacecraft, showing a suspected plume erupting in the same place on Europa in 2014 and 2016. Image via NASA/ ESA/ W. Sparks (STScI)/ USGS Astrogeology Science Center/ JPL-Caltech.

The plume would have disrupted both Europa’s extremely thin atmosphere and the magnetic field. This also would have changed the amount and behavior of the energetic protons. When the protons collided with uncharged particles from Europa’s atmosphere or plume, they took electrons from them, becoming uncharged particles themselves. As Hans Huybrighs from ESA, lead author of the new study, said:

This means they are no longer trapped in Jupiter’s magnetic field and can leave the system at high speed.

Therefore, the decreased number of protons detected during the flyby could be explained by a water vapor plume.

Last year, it was reported that water vapor itself had been directly detected above Europa’s surface by researchers using the W. M. Keck Observatory on Mauna Kea in Hawaii. According to NASA scientist Lucas Paganini:

Essential chemical elements (carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur) and sources of energy, two of three requirements for life, are found all over the solar system. But the third – liquid water – is somewhat hard to find beyond Earth. While scientists have not yet detected liquid water directly, we’ve found the next best thing: water in vapor form.

The water vapor signal was faint, however, and only seen once in 17 nights of observations in 2016 and 2017. The Hubble Space Telescope (HST) also took images in 2014 and 2016 that appear to show a plume in the same location. But even that wasn’t considered quite conclusive enough.

Saturn’s moon Enceladus was confirmed to have water vapor plumes by the Cassini spacecraft. This stunning photo shows then erupting through cracks in the ice crust at the moon’s south pole. Evidence suggests they are more active than those on Europa. Image via NASA Science.

Based on this and previous studies, the Europan plumes are probably less frequent and maybe smaller than those on Enceladus. But that doesn’t make them any less exciting. If they occur in a manner similar to the ones on Enceladus, then they probably originate from the subsurface ocean. Both Europa and Enceladus are now known to have global oceans below their outer ice crusts.

Cassini was able to sample the plumes at Enceladus, and found water vapor, methane, salts and organic molecules. It also found evidence for current active hydrothermal vents – just like in Earth’s oceans – on the ocean floor of Enceladus. The organics by themselves don’t prove yet there is life there, but combined with the hydrothermal clues, they point to a likely habitable environment in Enceladus’ ocean. Is the same true for Europa?

The Juno probe currently orbiting Jupiter isn’t able to conduct flybys of Europa, but NASA’s upcoming Europa Clipper mission, scheduled to launch in 2023, will make many such flybys. If the exact locations of any plumes can be determined beforehand, then Europa Clipper should be able to fly right through them, just like Cassini did at Enceladus. The composition could then be determined, and thus scientists could learn more about conditions in the ocean itself. ESA’s Jupiter Icy Moon Explorer (JUICE) mission to Jupiter, launching in 2022, will also be able to study Europa in more detail.

Although Europa is slightly smaller than our moon, its global subsurface ocean is estimated to contain more water than all the oceans on Earth combined. If there is any hydrothermal activity on the ocean bottom, as on Earth and Enceladus, that would increase the chances of the ocean being habitable, despite being completely hidden from sunlight by the ice crust. Even in deep oceans on Earth, a wide variety of life thrives around hot hydrothermal vents, with no sunlight needed.

Hans Huybrighs at ESA, lead author of the new study. Image via ESA.

The evidence for plumes on Europa seems stronger than ever, but absolute certainty may have to wait for either the Europa Clipper or JUICE mission. Confirmation would be exciting, allowing scientists a way to sample and analyze water coming from the ocean without having to drill through the ice (still a long way off), just like at Enceladus. And then, just maybe, we will be much closer to to answering the biggest question of all: is there life on Europa?

Bottom line: Scientists in Europe have found more evidence for water vapor plumes on Europa.

Source: An Active Plume Eruption on Europa During Galileo Flyby E26 as Indicated by Energetic Proton Depletions

Via MPS

Via ESA

from EarthSky https://ift.tt/2WHqkn3

Artist’s concept of water vapor plumes on Europa, the smallest of Jupiter’s 4 large Galilean moons. Image via ASA/ ESA/ K. Retherford/ SwRI/ Science.

The huge plumes of water vapor erupting through enormous cracks in the surface of Saturn’s moon Enceladus were quickly found by the Cassini spacecraft after it began orbiting Saturn in 2004. They’re thought to arise from a salty global ocean below the moon’s ice crust. Over the past few years, evidence has been accumulating for watery plumes on Jupiter’s large ocean moon Europa, too. It’s taking longer to put the pieces of the puzzle together, but – although still not definitive – the data for plumes on Europa are beginning to look compelling. They indicate that geyser-like plumes erupt from Europa’s surface, at least occasionally. On May 12, 2020, researchers at the Max Planck Institute for Solar System Research (MPS) in Germany and the European Space Agency (ESA) reported yet more evidence for water plumes on Europa.

The new work supports previous studies that suggested that – although it wasn’t recognized at the time – NASA’s Galileo spacecraft glimpsed one of these plumes during a flyby of Europa in 2000. The researchers published their work in Geophysical Research Letters in late April.

Making the case for plumes on Europa has been a long process, since, from the evidence gathered so far, they are seemingly intermittent. In contrast, the plumes on Enceladus were large and easy to see and, at least at the time, were erupting continuously. MPS scientist Elias Roussos said in a statement:

 However, various theories, models, and sporadic observations suggest that Europa, too, can exhibit plumes.

Jupiter’s ocean moon Europa, as seen by Galileo. This image is a combination of images from 1995 and 1998. Scientists have found yet more evidence for water vapor plumes erupting from its icy surface, most likely originating in the ocean below. Image via NASA/ JPL-Caltech/ SETI Institute.

How did the researchers find further evidence for Europa’s plumes?

They used computer simulations to replicate the data from the Energetic Particles Detector (EPD) onboard Galileo during a flyby of Europa in 2000. EPD recorded the distribution of high-energy protons trapped in Jupiter’s powerful magnetic field, which is 20 times stronger than Earth’s. Europa orbits within that magnetic field. Back in 2000, the detector recorded fewer protons during the flyby than had been expected. At the time, it was thought that Europa itself was blocking the view of the detector.

But now the new study suggests something else. The researchers modeled the movements of protons during the flyby, in an attempt to reproduce the original results from Galileo. But – surprise – they found that the only model that matched the results was one where a water vapor plume was between Europa and the detector.

Composite photos from the Hubble Space Telescope and the Galileo spacecraft, showing a suspected plume erupting in the same place on Europa in 2014 and 2016. Image via NASA/ ESA/ W. Sparks (STScI)/ USGS Astrogeology Science Center/ JPL-Caltech.

The plume would have disrupted both Europa’s extremely thin atmosphere and the magnetic field. This also would have changed the amount and behavior of the energetic protons. When the protons collided with uncharged particles from Europa’s atmosphere or plume, they took electrons from them, becoming uncharged particles themselves. As Hans Huybrighs from ESA, lead author of the new study, said:

This means they are no longer trapped in Jupiter’s magnetic field and can leave the system at high speed.

Therefore, the decreased number of protons detected during the flyby could be explained by a water vapor plume.

Last year, it was reported that water vapor itself had been directly detected above Europa’s surface by researchers using the W. M. Keck Observatory on Mauna Kea in Hawaii. According to NASA scientist Lucas Paganini:

Essential chemical elements (carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur) and sources of energy, two of three requirements for life, are found all over the solar system. But the third – liquid water – is somewhat hard to find beyond Earth. While scientists have not yet detected liquid water directly, we’ve found the next best thing: water in vapor form.

The water vapor signal was faint, however, and only seen once in 17 nights of observations in 2016 and 2017. The Hubble Space Telescope (HST) also took images in 2014 and 2016 that appear to show a plume in the same location. But even that wasn’t considered quite conclusive enough.

Saturn’s moon Enceladus was confirmed to have water vapor plumes by the Cassini spacecraft. This stunning photo shows then erupting through cracks in the ice crust at the moon’s south pole. Evidence suggests they are more active than those on Europa. Image via NASA Science.

Based on this and previous studies, the Europan plumes are probably less frequent and maybe smaller than those on Enceladus. But that doesn’t make them any less exciting. If they occur in a manner similar to the ones on Enceladus, then they probably originate from the subsurface ocean. Both Europa and Enceladus are now known to have global oceans below their outer ice crusts.

Cassini was able to sample the plumes at Enceladus, and found water vapor, methane, salts and organic molecules. It also found evidence for current active hydrothermal vents – just like in Earth’s oceans – on the ocean floor of Enceladus. The organics by themselves don’t prove yet there is life there, but combined with the hydrothermal clues, they point to a likely habitable environment in Enceladus’ ocean. Is the same true for Europa?

The Juno probe currently orbiting Jupiter isn’t able to conduct flybys of Europa, but NASA’s upcoming Europa Clipper mission, scheduled to launch in 2023, will make many such flybys. If the exact locations of any plumes can be determined beforehand, then Europa Clipper should be able to fly right through them, just like Cassini did at Enceladus. The composition could then be determined, and thus scientists could learn more about conditions in the ocean itself. ESA’s Jupiter Icy Moon Explorer (JUICE) mission to Jupiter, launching in 2022, will also be able to study Europa in more detail.

Although Europa is slightly smaller than our moon, its global subsurface ocean is estimated to contain more water than all the oceans on Earth combined. If there is any hydrothermal activity on the ocean bottom, as on Earth and Enceladus, that would increase the chances of the ocean being habitable, despite being completely hidden from sunlight by the ice crust. Even in deep oceans on Earth, a wide variety of life thrives around hot hydrothermal vents, with no sunlight needed.

Hans Huybrighs at ESA, lead author of the new study. Image via ESA.

The evidence for plumes on Europa seems stronger than ever, but absolute certainty may have to wait for either the Europa Clipper or JUICE mission. Confirmation would be exciting, allowing scientists a way to sample and analyze water coming from the ocean without having to drill through the ice (still a long way off), just like at Enceladus. And then, just maybe, we will be much closer to to answering the biggest question of all: is there life on Europa?

Bottom line: Scientists in Europe have found more evidence for water vapor plumes on Europa.

Source: An Active Plume Eruption on Europa During Galileo Flyby E26 as Indicated by Energetic Proton Depletions

Via MPS

Via ESA

from EarthSky https://ift.tt/2WHqkn3

Learn to recognize the wildlife out your window

Is it a single busy squirrel you’re watching every day? Or is it a cast of characters? Image via Julian Avery/ The Conversation.

By Julian Avery, Pennsylvania State University

Watching the wildlife outside your window can boost your mental well-being, and it’s something lots of people have been doing a lot more of lately.

Maybe you’ve been wondering if you’re seeing one persistent gray squirrel or a rotating cast of furry characters. Maybe you’ve been thinking about which birds are passing through for the season and which are townies who stick around all year.

As a wildlife ecologist, I’ve learned to pay attention to patterns that show me what the animals outside my window are up to, and I usually know which individuals are my regulars.

Whether you’re spying on animals in a city, town or rural area, with a little background knowledge, you too can keep tabs on the private lives of your neighborhood critters.

Seasonal shifts change the players

For many species, winter is a time when individuals compete less with one another and gather in large groups.

For example, eastern cottontail rabbits congregate around areas with plenty of food and places to escape to. Birds form large mixed-species flocks, which helps them better find food and avoid being hunted. They even form temporary allegiances as they forage together, following specific individuals who help determine where the flock goes.

Seasonal migration means the abundance of particular species in one location can change over the course of the year. Image courtesy eBird.org

As the season changes to spring, migratory species start arriving. A steady parade of individuals moves through the neighborhood. As animals transition to their breeding season, plumage and appearances may change as they work to attract mates. For many species, defense of a piece of land becomes an overriding concern.

During the summer months, adult animal numbers stabilize, and the drive to establish a territory means you’re likely to have the same individuals active outside your windows for the majority of summer.

This white-throated sparrow is molting into breeding plumage before heading on to summer grounds. Image via Julian Avery/ The Conversation.

Splitting up the neighborhood

A territory is a chunk of habitat. Its size will vary depending on the amount of food and breeding resources it holds. A territory with few trees, for example, may need to be bigger to hold enough forage for the animal that owns the turf.

Territory sizes for different species can range from the size of a large kitchen table (common lizards like green anoles and skinks) to an area greater than 120 football fields (a raptor such as the Cooper’s hawk). The cool thing is that animal home ranges are governed by their own needs and often do not follow the lines of human fences and alleyways.

A territory map for anoles shows how these lizards each have their own home turf that can overlap with neighbors. Habitat in this case included individual trees and a fallen log toward the bottom of the map which offered basking and display space Image via Jordan Bush.

I like to think of animal territories as quilts that drape over your neighborhood. For some species, like anoles, the squares in that quilt will have many small and intricate pieces, and you could fit many quilt pieces within each individual human property boundary. Some of those pieces will even overlap other patches.

Small songbirds will have quilt patches that span several human properties, though they may use specific parts more than others. Larger species will have quilt patches that cover entire neighborhoods with one territory.

Frequently spotted

If you’ve become familiar with the animals in your neighborhood, chances are you’ll see some of the same individuals again year after year. Eastern cottontails are likely to live up to three years in the wild, and they stay in the same general territory throughout their lives. Even the young have a tendency to stay close to their birth place.

Researchers have recaptured gray squirrels year after year in their original territories. On average, these critters survive about six years and can live longer than 20.

View this post on Instagram

Have you ever seen anything so perfect? #blackcappedchickadee #nest in the #backyard … amazing output for their #tiny size, the female will wait till all are laid before she incubates. • • • • #biodiversity #babies #babyanimals #nature_perfection #nature_brilliance #birdsofinstagram #nesting #exploreeverything #explorepage #getoutside #birdwatching #animals #nature #naturephotography #wildlife #wildlife_perfection #wildlife_photography #bbcearth #bella_shots #animales @agsciences #pawilds #pennsylvaniaisbeautiful #naturalpennsylvania #animallover #animalphotography #nuts_about_birds

A post shared by Julian Avery (@evolutionavery) on May 2, 2020 at 4:15pm PDT

Birds also have long lives and will often stay in the same territory year after year. However, when eggs don’t hatch or young die in the nest, some birds may choose a new territory the following year. This means there can be high turnover in your local bird network if the local habitat is unpredictable or full of urban predators.

Birds that don’t migrate and stay in residence year-round, like chickadees, often have a tendency to stay in the same area, which means you’ll be seeing the same individual birds outside your window across seasons.

Some species will have territories that don’t overlap much at all. For others, the overlap can be extensive.

This means that generally during the breeding season, you could be watching many gray squirrels visiting outside your window.

There may also be a couple of male cottontails, but probably a single female because they tend to not overlap with other females.

Maybe you’ll spy the same pair of cardinals along with a reliable pair of chickadees. If you’re watching closely like I was the other day, you may get lucky and catch another male cardinal from the territory next door trying to flirt with your female, at least until her mate realizes what’s about to happen. That is a clue to the invisible lines birds have drawn between their own domains.

Plenty of anole territories can fit into one human-scaled backyard. Image via Julian Avery

When it comes to smaller animals, like lizards and insects, all bets are off for how many unique individuals are present outside your window. But you can expect more of everything as the number of native plants increases.

Tips for watching

If you’re interested in trying to keep track of particular wildlife friends through the window, try to watch for identifying marks.

Natural markings like a torn ear can help you keep track of individuals. Image via Julian Avery.

In my research, I attach colored bands to bird legs or mark the scales of turtles and snakes so we can figure out how many exist in an area. Many animals have enough individual variation that you can keep track of them using their natural unique marks and scars. Squirrels can have torn ears or injured tails, lizards can have unique scars or healed injuries, and birds can have subtle differences in color or pattern.

Also try paying attention to the maximum number you see at any one point. Where do they go after eating or basking? You may get lucky and spy a nest or resting place. See if you can spot other individuals coming from different directions and territories.

Maybe you’ll notice animal families expanding. Image via Julian Avery.

At my house, we had a nest of rabbit kits born under our deck. I thought there was only one surviving newborn because we never saw more than one offspring. Two weeks later, there were three babies foraging simultaneously in the yard, and it became clear that they’d previously been taking turns coming out of hiding.

If you start watching closely, I think you’ll find so much drama happening in your neighborhood that you may get hooked on the action.

Julian Avery, Assistant Research Professor of Wildlife Ecology and Conservation, Pennsylvania State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bottom line: Tips to recognizing individual birds, squirrels, and other wildlife out your window.

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

Is it a single busy squirrel you’re watching every day? Or is it a cast of characters? Image via Julian Avery/ The Conversation.

By Julian Avery, Pennsylvania State University

Watching the wildlife outside your window can boost your mental well-being, and it’s something lots of people have been doing a lot more of lately.

Maybe you’ve been wondering if you’re seeing one persistent gray squirrel or a rotating cast of furry characters. Maybe you’ve been thinking about which birds are passing through for the season and which are townies who stick around all year.

As a wildlife ecologist, I’ve learned to pay attention to patterns that show me what the animals outside my window are up to, and I usually know which individuals are my regulars.

Whether you’re spying on animals in a city, town or rural area, with a little background knowledge, you too can keep tabs on the private lives of your neighborhood critters.

Seasonal shifts change the players

For many species, winter is a time when individuals compete less with one another and gather in large groups.

For example, eastern cottontail rabbits congregate around areas with plenty of food and places to escape to. Birds form large mixed-species flocks, which helps them better find food and avoid being hunted. They even form temporary allegiances as they forage together, following specific individuals who help determine where the flock goes.

Seasonal migration means the abundance of particular species in one location can change over the course of the year. Image courtesy eBird.org

As the season changes to spring, migratory species start arriving. A steady parade of individuals moves through the neighborhood. As animals transition to their breeding season, plumage and appearances may change as they work to attract mates. For many species, defense of a piece of land becomes an overriding concern.

During the summer months, adult animal numbers stabilize, and the drive to establish a territory means you’re likely to have the same individuals active outside your windows for the majority of summer.

This white-throated sparrow is molting into breeding plumage before heading on to summer grounds. Image via Julian Avery/ The Conversation.

Splitting up the neighborhood

A territory is a chunk of habitat. Its size will vary depending on the amount of food and breeding resources it holds. A territory with few trees, for example, may need to be bigger to hold enough forage for the animal that owns the turf.

Territory sizes for different species can range from the size of a large kitchen table (common lizards like green anoles and skinks) to an area greater than 120 football fields (a raptor such as the Cooper’s hawk). The cool thing is that animal home ranges are governed by their own needs and often do not follow the lines of human fences and alleyways.

A territory map for anoles shows how these lizards each have their own home turf that can overlap with neighbors. Habitat in this case included individual trees and a fallen log toward the bottom of the map which offered basking and display space Image via Jordan Bush.

I like to think of animal territories as quilts that drape over your neighborhood. For some species, like anoles, the squares in that quilt will have many small and intricate pieces, and you could fit many quilt pieces within each individual human property boundary. Some of those pieces will even overlap other patches.

Small songbirds will have quilt patches that span several human properties, though they may use specific parts more than others. Larger species will have quilt patches that cover entire neighborhoods with one territory.

Frequently spotted

If you’ve become familiar with the animals in your neighborhood, chances are you’ll see some of the same individuals again year after year. Eastern cottontails are likely to live up to three years in the wild, and they stay in the same general territory throughout their lives. Even the young have a tendency to stay close to their birth place.

Researchers have recaptured gray squirrels year after year in their original territories. On average, these critters survive about six years and can live longer than 20.

View this post on Instagram

Have you ever seen anything so perfect? #blackcappedchickadee #nest in the #backyard … amazing output for their #tiny size, the female will wait till all are laid before she incubates. • • • • #biodiversity #babies #babyanimals #nature_perfection #nature_brilliance #birdsofinstagram #nesting #exploreeverything #explorepage #getoutside #birdwatching #animals #nature #naturephotography #wildlife #wildlife_perfection #wildlife_photography #bbcearth #bella_shots #animales @agsciences #pawilds #pennsylvaniaisbeautiful #naturalpennsylvania #animallover #animalphotography #nuts_about_birds

A post shared by Julian Avery (@evolutionavery) on May 2, 2020 at 4:15pm PDT

Birds also have long lives and will often stay in the same territory year after year. However, when eggs don’t hatch or young die in the nest, some birds may choose a new territory the following year. This means there can be high turnover in your local bird network if the local habitat is unpredictable or full of urban predators.

Birds that don’t migrate and stay in residence year-round, like chickadees, often have a tendency to stay in the same area, which means you’ll be seeing the same individual birds outside your window across seasons.

Some species will have territories that don’t overlap much at all. For others, the overlap can be extensive.

This means that generally during the breeding season, you could be watching many gray squirrels visiting outside your window.

There may also be a couple of male cottontails, but probably a single female because they tend to not overlap with other females.

Maybe you’ll spy the same pair of cardinals along with a reliable pair of chickadees. If you’re watching closely like I was the other day, you may get lucky and catch another male cardinal from the territory next door trying to flirt with your female, at least until her mate realizes what’s about to happen. That is a clue to the invisible lines birds have drawn between their own domains.

Plenty of anole territories can fit into one human-scaled backyard. Image via Julian Avery

When it comes to smaller animals, like lizards and insects, all bets are off for how many unique individuals are present outside your window. But you can expect more of everything as the number of native plants increases.

Tips for watching

If you’re interested in trying to keep track of particular wildlife friends through the window, try to watch for identifying marks.

Natural markings like a torn ear can help you keep track of individuals. Image via Julian Avery.

In my research, I attach colored bands to bird legs or mark the scales of turtles and snakes so we can figure out how many exist in an area. Many animals have enough individual variation that you can keep track of them using their natural unique marks and scars. Squirrels can have torn ears or injured tails, lizards can have unique scars or healed injuries, and birds can have subtle differences in color or pattern.

Also try paying attention to the maximum number you see at any one point. Where do they go after eating or basking? You may get lucky and spy a nest or resting place. See if you can spot other individuals coming from different directions and territories.

Maybe you’ll notice animal families expanding. Image via Julian Avery.

At my house, we had a nest of rabbit kits born under our deck. I thought there was only one surviving newborn because we never saw more than one offspring. Two weeks later, there were three babies foraging simultaneously in the yard, and it became clear that they’d previously been taking turns coming out of hiding.

If you start watching closely, I think you’ll find so much drama happening in your neighborhood that you may get hooked on the action.

Julian Avery, Assistant Research Professor of Wildlife Ecology and Conservation, Pennsylvania State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bottom line: Tips to recognizing individual birds, squirrels, and other wildlife out your window.

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

Look for the beautiful Northern Crown

Photo at top: Corona Borealis, the Northern Crown, with its brightest star Alphecca, via Fred Espenak and AstroPixels. Used with permission.

Tonight, look for a constellation that’s easy to see on the sky’s dome, if your sky is dark enough. Corona Borealis – aka the Northern Crown – is exciting to find. It’s an almost-perfect semicircle of stars. You’ll find this beautiful pattern in the evening sky from now until October.

The constellation Corona Borealis is located more or less along a line between two bright stars, Arcturus in the constellation Boötes the Herdsman and Vega in the constellation Lyra the Harp.

At nightfall and early evening, you’ll see Arcturus fairly high in the east to northeast, noticeable for its brightness and yellow-orange color. Vega will be rather low in the northeast – bright and blue-white in color. The Northern Crown is more or less between these 2 bright stars.

You’ll need a fairly dark sky to see Corona Borealis between Vega and Arcturus. It’s a semicircle of stars – very noticeable.

The brightest star in Corona Borealis is Alphecca, also known as Gemma, sometimes called the Pearl of the Crown. The name Alphecca originated with a description of Corona Borealis as the “broken one,” in reference to the fact that these stars appear in a semi-circle, rather than a full circle. Alphecca is a blue-white star, with an intrinsic luminosity some 60 times that of our sun. It’s located about 75 light-years from Earth.

The C-shaped constellation Corona Borealis shines between the constellations Boötes and Hercules. Constellation chart via IAU.

View at EarthSky Conmmunity Photos. | Dr Ski in Valencia, Philippines caught this photo of Arcturus and its constellation Bootes, next to the Northern Crown, on May 24, 2019. Thanks, Dr Ski!

Bottom line: Look for Corona Borealis – the Northern Crown – between the brilliant stars Arcturus and Vega tonight! This constellation is very noticeable, if you have a dark sky.

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

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from EarthSky https://ift.tt/3g1bijV

Photo at top: Corona Borealis, the Northern Crown, with its brightest star Alphecca, via Fred Espenak and AstroPixels. Used with permission.

Tonight, look for a constellation that’s easy to see on the sky’s dome, if your sky is dark enough. Corona Borealis – aka the Northern Crown – is exciting to find. It’s an almost-perfect semicircle of stars. You’ll find this beautiful pattern in the evening sky from now until October.

The constellation Corona Borealis is located more or less along a line between two bright stars, Arcturus in the constellation Boötes the Herdsman and Vega in the constellation Lyra the Harp.

At nightfall and early evening, you’ll see Arcturus fairly high in the east to northeast, noticeable for its brightness and yellow-orange color. Vega will be rather low in the northeast – bright and blue-white in color. The Northern Crown is more or less between these 2 bright stars.

You’ll need a fairly dark sky to see Corona Borealis between Vega and Arcturus. It’s a semicircle of stars – very noticeable.

The brightest star in Corona Borealis is Alphecca, also known as Gemma, sometimes called the Pearl of the Crown. The name Alphecca originated with a description of Corona Borealis as the “broken one,” in reference to the fact that these stars appear in a semi-circle, rather than a full circle. Alphecca is a blue-white star, with an intrinsic luminosity some 60 times that of our sun. It’s located about 75 light-years from Earth.

The C-shaped constellation Corona Borealis shines between the constellations Boötes and Hercules. Constellation chart via IAU.

View at EarthSky Conmmunity Photos. | Dr Ski in Valencia, Philippines caught this photo of Arcturus and its constellation Bootes, next to the Northern Crown, on May 24, 2019. Thanks, Dr Ski!

Bottom line: Look for Corona Borealis – the Northern Crown – between the brilliant stars Arcturus and Vega tonight! This constellation is very noticeable, if you have a dark sky.

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This isn’t a triple rainbow

View at EarthSky Community Photos. | Earl Martin in Everett, Washington captured this image of a rare reflection rainbow over Puget Sound on May 5, 2020. Thanks for sharing, Earl!

When he captured this photo, Earl Martin wondered if he’d caught a triple rainbow. But what experts in atmospheric optics call tertiary or quaternary rainbows are exceedingly rare. Read the latest on them – from 2011 – here: First-ever photos of triple and quadruple rainbows

So the photo above isn’t a triple rainbow. But it’s still a rare kind of rainbow, rare enough to cause most people to do a double-take. Earl caught what’s called a reflection rainbow, which can be caused sunlight beaming upwards after reflecting from wet sand or calm water. In this case, the reflection rainbow is coming the water of Puget Sound in the Pacific Northwest, located along the northwestern coast of the U.S. state of Washington.

On his page of explanation for reflection rainbow, Les Cowley of the website Atmospheric Optics has the following diagram, showing exactly how reflection rainbows form.

Diagram by Les Cowley at Atmospheric Optics.

You can see in this diagram just what’s in Earl’s photo at top, a double rainbow (labeled primary and secondary bows in the diagram above), plus one reflection rainbow. Les wrote of the diagram:

The centers of reflection bows are at the same altitude as the sun – the anthelic point [point on the celestial sphere which lies directly opposite the sun from the observer]. This is the same distance above the horizon as the centers of normal bows are below it at the antisolar point.

The normal bow and its corresponding reflection bow intersect at the horizon.

Reflection bows are usually brightest when the sun is low because then its light is reflected most strongly from water surfaces. The normal and reflection bows draw closer together as the sun gets lower.

The source of the reflected light is usually water behind you, i.e. sunwards. It can be in front of you but then only the base of the reflected bow will be seen.

Thank you, Les, and thank you, Earl!

Bottom line: The photo shows what looks like an ordinary double rainbow with a third rainbow, at an odd angle, in their midst. The third rainbow is the reflection rainbow, reflected from the water in Puget Sound on May 5, 2020.

More: Another reflection rainbow photo, showing 4 rainbows this time, from 2015

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View at EarthSky Community Photos. | Earl Martin in Everett, Washington captured this image of a rare reflection rainbow over Puget Sound on May 5, 2020. Thanks for sharing, Earl!

When he captured this photo, Earl Martin wondered if he’d caught a triple rainbow. But what experts in atmospheric optics call tertiary or quaternary rainbows are exceedingly rare. Read the latest on them – from 2011 – here: First-ever photos of triple and quadruple rainbows

So the photo above isn’t a triple rainbow. But it’s still a rare kind of rainbow, rare enough to cause most people to do a double-take. Earl caught what’s called a reflection rainbow, which can be caused sunlight beaming upwards after reflecting from wet sand or calm water. In this case, the reflection rainbow is coming the water of Puget Sound in the Pacific Northwest, located along the northwestern coast of the U.S. state of Washington.

On his page of explanation for reflection rainbow, Les Cowley of the website Atmospheric Optics has the following diagram, showing exactly how reflection rainbows form.

Diagram by Les Cowley at Atmospheric Optics.

You can see in this diagram just what’s in Earl’s photo at top, a double rainbow (labeled primary and secondary bows in the diagram above), plus one reflection rainbow. Les wrote of the diagram:

The centers of reflection bows are at the same altitude as the sun – the anthelic point [point on the celestial sphere which lies directly opposite the sun from the observer]. This is the same distance above the horizon as the centers of normal bows are below it at the antisolar point.

The normal bow and its corresponding reflection bow intersect at the horizon.

Reflection bows are usually brightest when the sun is low because then its light is reflected most strongly from water surfaces. The normal and reflection bows draw closer together as the sun gets lower.

The source of the reflected light is usually water behind you, i.e. sunwards. It can be in front of you but then only the base of the reflected bow will be seen.

Thank you, Les, and thank you, Earl!

Bottom line: The photo shows what looks like an ordinary double rainbow with a third rainbow, at an odd angle, in their midst. The third rainbow is the reflection rainbow, reflected from the water in Puget Sound on May 5, 2020.

More: Another reflection rainbow photo, showing 4 rainbows this time, from 2015

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Giant star cluster Omega Centauri

The globular cluster Omega Centauri seen from ESO’s La Silla Observatory. Image via Wikimedia Commons.

Having a mass of 5 million suns, Omega Centauri is 10 times more massive than a typical globular cluster. Omega Centauri has a diameter of 230 light-years. It’s a stellar city sparkling with perhaps 10 million stars. Globular clusters generally have stars of similar age and composition. However, studies of Omega Centauri reveal that this cluster has different stellar populations that formed at varying periods of time. It may be that Omega Centauri is a remnant of a small galaxy that merged with the Milky Way.

Spica, the brightest star in the constellation Virgo, serves as your guide star to the Omega Centauri globular star cluster. When Spica is highest up for the night, so is Omega Centauri!

How to see Omega Centauri. Omega Centauri – the Milky Way galaxy’s largest and most luminous globular star cluster – is far to the south on the sky’s dome. It’s visible from the southern half of the United States, or south of 40 degrees north latitude (the latitude of Denver, Colorado). Canadians hasten to remind us that they can spot Omega Centauri from as far north as Point Pelee in Canada (42 degrees latitude). When seeing conditions are just right, they can catch the Omega Cenaturi star cluster skimming along the surface of Lake Erie, they say.

From the Southern Hemisphere, Omega Centauri appears much higher in the sky and is a glorious sight.

If you’re in the Northern Hemisphere and want to spot this cluster, know that Omega Centauri can only be seen at certain times of the year. It’s best seen in the evening sky from the Northern Hemisphere on late April, May and June evenings.

Around mid-May, this wondrous star cluster is highest up and due south around 11 p.m. local daylight saving time.

By mid-June, Omega Centauri is highest up and due south around 10 p.m. local daylight saving time.

Northern Hemisphere residents can see Omega Centauri from January through April as well, but they must be willing to stay up past midnight or to get up before dawn.

Spica, the brightest star in the constellation Virgo, serves as your guide star to Omega Centauri. When Spica and Omega Centauri transit – appear due south and reach the highest point in the sky – they do so in unison. However, Omega Centauri transits about 35 degrees south of (or below) sparkling blue-white Spica. For reference, your fist at arm’s length approximates 10 degrees of sky. Find Spica’s transit time for your sky at this U.S. Naval Observatory page, or follow the arc in the handle of the Big Dipper to find Spica.

Use the search function in Stellarium-Web.org to locate sky objects as viewed from your location

Omega Centauri in infrared, via Spitzer Space Telescope/ Wikimedia Commons.

Omega Centauri is a globular, not an open, star cluster. The symmetrical, round appearance of Omega Centauri distinguishes it from clusters such as the Pleiades and Hyades, which are open star clusters.

An open star cluster is a loose gathering of dozens to hundreds of young stars within the disk of the Milky Way galaxy. Open clusters are weakly held together by gravity, and tend to disperse after several hundreds of millions of years.

Globular clusters orbit the Milky Way outside the galactic disk. They harbor tens of thousands to millions of stars. Tightly bound by gravity, globular clusters remain intact after 12 billion years.

Generally, open clusters visible to the unaided eye are hundreds to a few thousand light-years away. In contrast, globular clusters are generally tens of thousands of light-years distant.

At 16,000 to 18,000 light-years, Omega Centauri is one of the few of the galaxy’s 200 or so globular clusters that is visible to the unaided eye. It looks like a faint, fuzzy star, but Omega Centauri’s mere presence testifies to its size and brilliance. Like any globular cluster, Omega Centauri is best appreciated with a telescope.

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Omega Centauri’s position is at Right Ascension: 13h 26.8m; Declination: 47 degrees 29′ south

Bottom line: The globular star cluster Omega Centauri is by far the largest globular cluster known, as seen from Earth. It’s about 10 times more massive than a typical globular cluster.

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The globular cluster Omega Centauri seen from ESO’s La Silla Observatory. Image via Wikimedia Commons.

Having a mass of 5 million suns, Omega Centauri is 10 times more massive than a typical globular cluster. Omega Centauri has a diameter of 230 light-years. It’s a stellar city sparkling with perhaps 10 million stars. Globular clusters generally have stars of similar age and composition. However, studies of Omega Centauri reveal that this cluster has different stellar populations that formed at varying periods of time. It may be that Omega Centauri is a remnant of a small galaxy that merged with the Milky Way.

Spica, the brightest star in the constellation Virgo, serves as your guide star to the Omega Centauri globular star cluster. When Spica is highest up for the night, so is Omega Centauri!

How to see Omega Centauri. Omega Centauri – the Milky Way galaxy’s largest and most luminous globular star cluster – is far to the south on the sky’s dome. It’s visible from the southern half of the United States, or south of 40 degrees north latitude (the latitude of Denver, Colorado). Canadians hasten to remind us that they can spot Omega Centauri from as far north as Point Pelee in Canada (42 degrees latitude). When seeing conditions are just right, they can catch the Omega Cenaturi star cluster skimming along the surface of Lake Erie, they say.

From the Southern Hemisphere, Omega Centauri appears much higher in the sky and is a glorious sight.

If you’re in the Northern Hemisphere and want to spot this cluster, know that Omega Centauri can only be seen at certain times of the year. It’s best seen in the evening sky from the Northern Hemisphere on late April, May and June evenings.

Around mid-May, this wondrous star cluster is highest up and due south around 11 p.m. local daylight saving time.

By mid-June, Omega Centauri is highest up and due south around 10 p.m. local daylight saving time.

Northern Hemisphere residents can see Omega Centauri from January through April as well, but they must be willing to stay up past midnight or to get up before dawn.

Spica, the brightest star in the constellation Virgo, serves as your guide star to Omega Centauri. When Spica and Omega Centauri transit – appear due south and reach the highest point in the sky – they do so in unison. However, Omega Centauri transits about 35 degrees south of (or below) sparkling blue-white Spica. For reference, your fist at arm’s length approximates 10 degrees of sky. Find Spica’s transit time for your sky at this U.S. Naval Observatory page, or follow the arc in the handle of the Big Dipper to find Spica.

Use the search function in Stellarium-Web.org to locate sky objects as viewed from your location

Omega Centauri in infrared, via Spitzer Space Telescope/ Wikimedia Commons.

Omega Centauri is a globular, not an open, star cluster. The symmetrical, round appearance of Omega Centauri distinguishes it from clusters such as the Pleiades and Hyades, which are open star clusters.

An open star cluster is a loose gathering of dozens to hundreds of young stars within the disk of the Milky Way galaxy. Open clusters are weakly held together by gravity, and tend to disperse after several hundreds of millions of years.

Globular clusters orbit the Milky Way outside the galactic disk. They harbor tens of thousands to millions of stars. Tightly bound by gravity, globular clusters remain intact after 12 billion years.

Generally, open clusters visible to the unaided eye are hundreds to a few thousand light-years away. In contrast, globular clusters are generally tens of thousands of light-years distant.

At 16,000 to 18,000 light-years, Omega Centauri is one of the few of the galaxy’s 200 or so globular clusters that is visible to the unaided eye. It looks like a faint, fuzzy star, but Omega Centauri’s mere presence testifies to its size and brilliance. Like any globular cluster, Omega Centauri is best appreciated with a telescope.

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Omega Centauri’s position is at Right Ascension: 13h 26.8m; Declination: 47 degrees 29′ south

Bottom line: The globular star cluster Omega Centauri is by far the largest globular cluster known, as seen from Earth. It’s about 10 times more massive than a typical globular cluster.

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Here’s how SOHO and a skywatcher discovered Comet SWAN

The movement of Comet C/2020 F8 (SWAN) through successive all-sky maps as observed with the SWAN instrument on SOHO during the period from April 1 to May 9, 2020. Image via ESA.

This article comes from the European Space Agency (ESA). It was originally published on May 13, 2020.

Currently crossing the skies above Earth, Comet C/2020 F8 (SWAN) is grazing the northeastern horizon before dawn now and has some potential to become more prominent object by late May or early June. Yet it wasn’t discovered by someone looking up at the night sky. Instead, the person was looking at a computer screen.

Amateur astronomer Michael Mattiazzo from Australia spotted this icy visitor from the outer solar system while inspecting images that had been posted online from the Solar Wind ANisotropies (SWAN) instrument aboard SOHO, the ESA/NASA Solar and Heliospheric Observatory.

SWAN captures images in ultraviolet light, including a specific ultraviolet wavelength called Lyman alpha. This is a wavelength that is characteristically emitted by hydrogen atoms. The instrument’s primary goal is to map changes in the solar wind, the variable flow of charged particles that is continuously released by the sun into interplanetary space. In addition, it has become an effective discoverer of comets, too, because comets are also sources of hydrogen.

Read more and find charts: Will you see Comet SWAN?

Check out the raw SOHO/SWAN images online

View larger. | Anatomy of a comet. Image via ESA.

In the case of a comet, the hydrogen comes from the water vapor the icy core releases into space when heated by the sun. And there is more, as solar radiation can break water molecules (H2O) into a single hydrogen atom (H) and a hydrogen-oxygen pair (which scientists call a hydroxyl radical, or OH). The result is a cloud of hydrogen that surrounds the comet, giving off a bright spot of Lyman-alpha light that can be spotted in the SWAN maps.

Almost every day, SWAN records a complete map of the sky. These raw sky maps are full of stars, making it difficult to pick out new comets, which may arrive at random from any direction. To make the job easier, successive maps are automatically subtracted from one another, removing the stars and leaving only variable or moving sources visible.

These ‘difference images’ are regularly posted online on the SOHO website, meaning that anyone with internet access can look at these ‘comet tracker’s maps’ and join the search for new comets. To date, 12 of them have been spotted in the SWAN data since 1996, all of them by amateur astronomers, or citizen scientists as they are also known.

In the case of this current comet, Mattiazzo (who has already discovered eight comets using this method) found it by comparing the SWAN maps from several days in early April 2020.

Comet SWAN in all-sky map from SOHO. Image via ESA.

From discovery to observation

Once the comet had been announced, Austrian astrophotographer Gerald Rhemann obtained a beautiful image of it from the desert in Namibia, clearly showing the spherical gas cloud of the comet’s coma and its extended ion tail. When the image was published as Astronomy Picture of the Day (APOD) on April 29, it helped bring the comet to wide scale attention.

Another image, taken a few days later by British astrophotographer Damian Peach using a remote telescope in Chile and also featured as APOD, portrays the impressive comet’s tail as it closed in on Earth. The closest approach is estimated for May 13, at around 85 million km from our planet.

The SWAN team’s comet expert, Michael Combi from the University of Michigan, estimates that by April 15 the comet was ejecting about 1300 kg of water vapor every second, or about 4.4×1028 H2O molecules every second. That is a fast rate of ejection when compared to other comets. Jean-Loup Bertaux, former principal investigator and proposer of the SWAN instrument, said:

This is already three times more than Comet 67P/Churyumov-Gerasimenko at its best, when it was visited by ESA’s Rosetta mission between 2014 and 2016.

Will Comet SWAN become an obvious naked eye object?

The comet’s vigor could be significant for observers on Earth. The more material ejected from the comet, the more sunlight it reflects and the more visible it becomes. The comet has moved from the southern to the northern skies. It has not brightened as expected, based on estimates from last month. However, it could brighten as it approaches its May 27 perihelion, or closest point to the sun – if it survives that long.

Comets are fragile objects, and can often break apart as they approach the sun. In late April, the much anticipated Comet ATLAS suffered this fate, breaking into at least 30 fragments. Comet SWAN is now entering the ‘danger zone’ and – at its closest point to the sun on May 27 – the solar heating will be at its maximum.

It can be extremely difficult to predict the behavior of comets that make such close approaches to the sun, but scientists are hopeful that Comet SWAN will remain bright enough to see as it continues its journey. If the comet survives, stargazers on Earth should look for it near the bright star Capella in the constellation of Auriga, the Charioteer. This is almost certainly the only time the comet will be visible in our lifetimes: estimates are not yet fully precise, but it is clear that the comet’s orbital period is measured in thousands or even millions of years.

Find charts and observing tips for Comet SWAN here.

SOHO’s 3000th comet, discovered in 2015 by a comet hunter from Thailand. Image via ESA.

Waiting for the 4,000th comet

Although Comet SWAN is only the 12th discovery from that particular instrument, it is the 3,932nd comet discovered by SOHO.

This extraordinary number is thanks to the Large Angle and Spectrometric Coronagraph Experiment (LASCO) instrument, with significant help from members of the public.

Karl Battams is LASCO team comet expert at the US Naval Research Laboratory and lead researcher of the Sungrazer Project. He said:

Almost all of SOHO’s comet discoveries so far have been made by citizen scientists scouring images returned by SOHO’s LASCO instrument.

Bernhard Fleck, ESA SOHO project scientist, said:

It’s extremely exciting that our sun-watching observatory has spotted so many comets since its launch in 1995. We are eagerly awaiting, along with comet enthusiasts around the world, for the 4,000th discovery, which might happen real soon.

Bottom line: Currently crossing the skies above Earth, Comet C/2020 F8 (SWAN) is grazing the northeastern horizon before dawn now and has some potential to become more prominent object by late May or early June. Yet it wasn’t discovered by someone looking up at the night sky. Instead, the person was looking at a computer screen.

Via ESA

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The movement of Comet C/2020 F8 (SWAN) through successive all-sky maps as observed with the SWAN instrument on SOHO during the period from April 1 to May 9, 2020. Image via ESA.

This article comes from the European Space Agency (ESA). It was originally published on May 13, 2020.

Currently crossing the skies above Earth, Comet C/2020 F8 (SWAN) is grazing the northeastern horizon before dawn now and has some potential to become more prominent object by late May or early June. Yet it wasn’t discovered by someone looking up at the night sky. Instead, the person was looking at a computer screen.

Amateur astronomer Michael Mattiazzo from Australia spotted this icy visitor from the outer solar system while inspecting images that had been posted online from the Solar Wind ANisotropies (SWAN) instrument aboard SOHO, the ESA/NASA Solar and Heliospheric Observatory.

SWAN captures images in ultraviolet light, including a specific ultraviolet wavelength called Lyman alpha. This is a wavelength that is characteristically emitted by hydrogen atoms. The instrument’s primary goal is to map changes in the solar wind, the variable flow of charged particles that is continuously released by the sun into interplanetary space. In addition, it has become an effective discoverer of comets, too, because comets are also sources of hydrogen.

Read more and find charts: Will you see Comet SWAN?

Check out the raw SOHO/SWAN images online

View larger. | Anatomy of a comet. Image via ESA.

In the case of a comet, the hydrogen comes from the water vapor the icy core releases into space when heated by the sun. And there is more, as solar radiation can break water molecules (H2O) into a single hydrogen atom (H) and a hydrogen-oxygen pair (which scientists call a hydroxyl radical, or OH). The result is a cloud of hydrogen that surrounds the comet, giving off a bright spot of Lyman-alpha light that can be spotted in the SWAN maps.

Almost every day, SWAN records a complete map of the sky. These raw sky maps are full of stars, making it difficult to pick out new comets, which may arrive at random from any direction. To make the job easier, successive maps are automatically subtracted from one another, removing the stars and leaving only variable or moving sources visible.

These ‘difference images’ are regularly posted online on the SOHO website, meaning that anyone with internet access can look at these ‘comet tracker’s maps’ and join the search for new comets. To date, 12 of them have been spotted in the SWAN data since 1996, all of them by amateur astronomers, or citizen scientists as they are also known.

In the case of this current comet, Mattiazzo (who has already discovered eight comets using this method) found it by comparing the SWAN maps from several days in early April 2020.

Comet SWAN in all-sky map from SOHO. Image via ESA.

From discovery to observation

Once the comet had been announced, Austrian astrophotographer Gerald Rhemann obtained a beautiful image of it from the desert in Namibia, clearly showing the spherical gas cloud of the comet’s coma and its extended ion tail. When the image was published as Astronomy Picture of the Day (APOD) on April 29, it helped bring the comet to wide scale attention.

Another image, taken a few days later by British astrophotographer Damian Peach using a remote telescope in Chile and also featured as APOD, portrays the impressive comet’s tail as it closed in on Earth. The closest approach is estimated for May 13, at around 85 million km from our planet.

The SWAN team’s comet expert, Michael Combi from the University of Michigan, estimates that by April 15 the comet was ejecting about 1300 kg of water vapor every second, or about 4.4×1028 H2O molecules every second. That is a fast rate of ejection when compared to other comets. Jean-Loup Bertaux, former principal investigator and proposer of the SWAN instrument, said:

This is already three times more than Comet 67P/Churyumov-Gerasimenko at its best, when it was visited by ESA’s Rosetta mission between 2014 and 2016.

Will Comet SWAN become an obvious naked eye object?

The comet’s vigor could be significant for observers on Earth. The more material ejected from the comet, the more sunlight it reflects and the more visible it becomes. The comet has moved from the southern to the northern skies. It has not brightened as expected, based on estimates from last month. However, it could brighten as it approaches its May 27 perihelion, or closest point to the sun – if it survives that long.

Comets are fragile objects, and can often break apart as they approach the sun. In late April, the much anticipated Comet ATLAS suffered this fate, breaking into at least 30 fragments. Comet SWAN is now entering the ‘danger zone’ and – at its closest point to the sun on May 27 – the solar heating will be at its maximum.

It can be extremely difficult to predict the behavior of comets that make such close approaches to the sun, but scientists are hopeful that Comet SWAN will remain bright enough to see as it continues its journey. If the comet survives, stargazers on Earth should look for it near the bright star Capella in the constellation of Auriga, the Charioteer. This is almost certainly the only time the comet will be visible in our lifetimes: estimates are not yet fully precise, but it is clear that the comet’s orbital period is measured in thousands or even millions of years.

Find charts and observing tips for Comet SWAN here.

SOHO’s 3000th comet, discovered in 2015 by a comet hunter from Thailand. Image via ESA.

Waiting for the 4,000th comet

Although Comet SWAN is only the 12th discovery from that particular instrument, it is the 3,932nd comet discovered by SOHO.

This extraordinary number is thanks to the Large Angle and Spectrometric Coronagraph Experiment (LASCO) instrument, with significant help from members of the public.

Karl Battams is LASCO team comet expert at the US Naval Research Laboratory and lead researcher of the Sungrazer Project. He said:

Almost all of SOHO’s comet discoveries so far have been made by citizen scientists scouring images returned by SOHO’s LASCO instrument.

Bernhard Fleck, ESA SOHO project scientist, said:

It’s extremely exciting that our sun-watching observatory has spotted so many comets since its launch in 1995. We are eagerly awaiting, along with comet enthusiasts around the world, for the 4,000th discovery, which might happen real soon.

Bottom line: Currently crossing the skies above Earth, Comet C/2020 F8 (SWAN) is grazing the northeastern horizon before dawn now and has some potential to become more prominent object by late May or early June. Yet it wasn’t discovered by someone looking up at the night sky. Instead, the person was looking at a computer screen.

Via ESA

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Murder hornets? 5 questions answered about Asian giant hornets in North America

Asian giant hornets (Vespa mandarinia japonica) drinking sap from tree bark in Japan. Image via Alpsdake/Wikipedia

By Akito Y Kawahara, University of Florida

Editor’s note: According to recent press reports, two Asian giant hornets – a species not known to occur in North America – were found in northwest Washington state in late 2019, and a hornet colony was found and eliminated in British Columbia. Now scientists are trying to determine whether more of these large predatory insects are present in the region. Entomologist Akito Kawahara explains why headlines referring to “murder hornets” are misleading.

1. How common are these hornets in Asia, and how much alarm do they cause?

The Asian giant hornet (Vespa mandarinia) is fairly common in many parts of Asia, where it is called the “Giant hornet.” Growing up in Japan, I saw them relatively frequently in the mountains outside of Tokyo.

These insects are large and distinctive, with a characteristic orange head and black-banded orange body. Like any other social wasp, they will defend their nest if the colony is disrupted. But in most cases they will not do anything if people aren’t aggressive toward them.

Giant hornets have longer stingers than a honeybee’s, and hornets do not break off their stingers when they sting. Because hornet stingers can puncture thick clothing, people should avoid hornets and their nests whenever possible.

Giant hornets frequently are attracted to tree sap: I was stung by one when I was looking for butterflies on trees. The sting is painful, but the swelling and pain in most cases subside in a few days.

Just as with honey bee stings, an allergic reaction, or anaphylaxis, can occasionally put people in the hospital. In rare cases, severe reactions can become fatal. But wasp and hornet stings killed less than 13 people a year in 2017 and 2018 in Japan – less than 0.00001% of the national population – in a country where many people spend time in the woods.

If you are allergic to bee and wasp stings, it is best to avoid getting close to these insects and their nests, wear white clothing outdoors (they are attracted to dark colors), and avoid carrying open-top sweet drinks such as sodas in the woods.

Barricade and warning sign in front of Giant hornet nest under a tree stump in Deba, Ritto City, Japan. Image via Greg Peterson/ Flickr

2. Are you surprised that the hornets have appeared in North America?

To some degree, yes. Most likely, a single, fertile queen hornet entered Canada via shipping packaging and created the colony that was discovered in 2019.

It’s easy for invasive species to travel this way. More than 19,000 cargo containers arrive daily at U.S. ports, and inspectors can only do random searches of shipping containers. One estimate suggests that just 2% of shipments are searched for evidence of harmful organisms such as plant pests. Many invasive species are intercepted, but some do get through.

It’s very unlikely that an entire colony of hornets was transferred to North America. Colonies of this hornet are often large, and the hornets would be visible and potentially aggressive if their nest were disturbed.

A genetic test indicated that one of the hornets found in Washington was not related to the Canadian colony, but those results have not been published or peer reviewed. The Giant hornet has not been found in 2020 in either the U.S. or Canada.

Four wasp and hornet species often confused with the giant hornet. Upper left: European hornet (Vespa crabro). Upper right: Common aerial yellowjacket (Dolichovespula arenaria). Lower left: European paper wasp (Polistes dominula). Lower right: Baldfaced hornet (Dolichovespula maculata). Images vie gailhampshire (upper left), Gilles Gonthier (upper right), Judy Gallagher (bottom images)/ Flickr

3. What kind of conditions do these insects need to live?

Giant hornets are fairly common in mountainous regions of Asia, but they’re not often seen in large cities or highly urbanized areas. They usually nest at the base of large trees and inside dead logs. The fact that they can’t tolerate extremely hot or cold temperatures makes it unlikely that they would spread to very hot or cold areas of North America.

If active colonies are discovered in 2020 in the Pacific Northwest, which has a more temperate climate, it’s possible that they could spread there. However, it is unlikely that this would happen quickly, as foraging ranges of Vespa are only about 2,300 feet (700 meters) from their nest.

The key to prevent spread is surveillance. Anyone in the Pacific Northwest should be alert for Giant hornets while they are outdoors this summer and fall.

4. If more hornets are found, could they threaten honeybees and other pollinators?

Possibly. Some media posts have described destruction of honeybee nests by what could have been Giant hornets, but honeybees are not these insects’ only prey. The hornets feed on different kinds of insects, and bring captured dead prey back to their hive to feed to their young.

In Japan, beekeepers surround their hives with wire screen nets to protect them from hornets. North American beekeepers can replicate these with wire netting from local hardware stores.

Many honeybees in Asia have the ability to protect their hive from intruding Giant hornets by scorching them. They wait for a hornet to enter their nest, then mob it by surrounding it completely with their bodies. Each honeybee vibrates its wings, and the combined warming of honey bee bodies raises the temperature in the center of the cluster to 122 degrees F (50 degrees C), killing the hornet. Carbon dioxide levels in the nest also increase during this process, which contributes to the hornet’s death.

Japanese honey bees swarm a Giant hornet, killing it with their body heat.

5. Are news stories about “murder hornets” overreacting?

Yes, very much so. In parts of Japan, people consider these hornets beneficial because they remove pests, such as harmful caterpillars, from crops. They are also thought to contain nutrients, and have been used as ingredients in Japanese food and some strong liquors. Some people believe the hornets’ essence has medicinal benefits.

People who live in Vancouver, Seattle or nearby should certainly take note of what these insects look like. They are 2 inches long or more, with a 3-inch wingspan, and have distinctly orange heads and broad striped orange and black-banded abdomens. That’s different from typical North American hornets, which have yellow or white bodies with black marks.

In the unlikely case that you see a Giant hornet in Washington state, do not try to remove nests yourself or spray hornets with pesticides. Cutting down trees to prevent nesting sites is also unnecessary, and can affect many other kinds of native wildlife, including beneficial insects that are needed for pollination and decomposition. Many native insects are declining globally, and it’s important to make sure these insects are not affected.

Instead, take a photo from a distance and report it to the Washington State Department of Agriculture. Photos are essential to verify that identifications are accurate.

Consider also uploading your images to iNaturalist, which is one of the primary sources for information on tracking wildlife. The images are archived and carry data, such as location, time of observance and the insect’s morphological features, that scientists can use for research.

Akito Y Kawahara, Associate Professor and Curator of Insects, Florida Museum of Natural History, University of Florida

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bottom line: What are Asian giant hornets? Do they deserve the nickname “murder hornets?” An entomologist says no.

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

Asian giant hornets (Vespa mandarinia japonica) drinking sap from tree bark in Japan. Image via Alpsdake/Wikipedia

By Akito Y Kawahara, University of Florida

Editor’s note: According to recent press reports, two Asian giant hornets – a species not known to occur in North America – were found in northwest Washington state in late 2019, and a hornet colony was found and eliminated in British Columbia. Now scientists are trying to determine whether more of these large predatory insects are present in the region. Entomologist Akito Kawahara explains why headlines referring to “murder hornets” are misleading.

1. How common are these hornets in Asia, and how much alarm do they cause?

The Asian giant hornet (Vespa mandarinia) is fairly common in many parts of Asia, where it is called the “Giant hornet.” Growing up in Japan, I saw them relatively frequently in the mountains outside of Tokyo.

These insects are large and distinctive, with a characteristic orange head and black-banded orange body. Like any other social wasp, they will defend their nest if the colony is disrupted. But in most cases they will not do anything if people aren’t aggressive toward them.

Giant hornets have longer stingers than a honeybee’s, and hornets do not break off their stingers when they sting. Because hornet stingers can puncture thick clothing, people should avoid hornets and their nests whenever possible.

Giant hornets frequently are attracted to tree sap: I was stung by one when I was looking for butterflies on trees. The sting is painful, but the swelling and pain in most cases subside in a few days.

Just as with honey bee stings, an allergic reaction, or anaphylaxis, can occasionally put people in the hospital. In rare cases, severe reactions can become fatal. But wasp and hornet stings killed less than 13 people a year in 2017 and 2018 in Japan – less than 0.00001% of the national population – in a country where many people spend time in the woods.

If you are allergic to bee and wasp stings, it is best to avoid getting close to these insects and their nests, wear white clothing outdoors (they are attracted to dark colors), and avoid carrying open-top sweet drinks such as sodas in the woods.

Barricade and warning sign in front of Giant hornet nest under a tree stump in Deba, Ritto City, Japan. Image via Greg Peterson/ Flickr

2. Are you surprised that the hornets have appeared in North America?

To some degree, yes. Most likely, a single, fertile queen hornet entered Canada via shipping packaging and created the colony that was discovered in 2019.

It’s easy for invasive species to travel this way. More than 19,000 cargo containers arrive daily at U.S. ports, and inspectors can only do random searches of shipping containers. One estimate suggests that just 2% of shipments are searched for evidence of harmful organisms such as plant pests. Many invasive species are intercepted, but some do get through.

It’s very unlikely that an entire colony of hornets was transferred to North America. Colonies of this hornet are often large, and the hornets would be visible and potentially aggressive if their nest were disturbed.

A genetic test indicated that one of the hornets found in Washington was not related to the Canadian colony, but those results have not been published or peer reviewed. The Giant hornet has not been found in 2020 in either the U.S. or Canada.

Four wasp and hornet species often confused with the giant hornet. Upper left: European hornet (Vespa crabro). Upper right: Common aerial yellowjacket (Dolichovespula arenaria). Lower left: European paper wasp (Polistes dominula). Lower right: Baldfaced hornet (Dolichovespula maculata). Images vie gailhampshire (upper left), Gilles Gonthier (upper right), Judy Gallagher (bottom images)/ Flickr

3. What kind of conditions do these insects need to live?

Giant hornets are fairly common in mountainous regions of Asia, but they’re not often seen in large cities or highly urbanized areas. They usually nest at the base of large trees and inside dead logs. The fact that they can’t tolerate extremely hot or cold temperatures makes it unlikely that they would spread to very hot or cold areas of North America.

If active colonies are discovered in 2020 in the Pacific Northwest, which has a more temperate climate, it’s possible that they could spread there. However, it is unlikely that this would happen quickly, as foraging ranges of Vespa are only about 2,300 feet (700 meters) from their nest.

The key to prevent spread is surveillance. Anyone in the Pacific Northwest should be alert for Giant hornets while they are outdoors this summer and fall.

4. If more hornets are found, could they threaten honeybees and other pollinators?

Possibly. Some media posts have described destruction of honeybee nests by what could have been Giant hornets, but honeybees are not these insects’ only prey. The hornets feed on different kinds of insects, and bring captured dead prey back to their hive to feed to their young.

In Japan, beekeepers surround their hives with wire screen nets to protect them from hornets. North American beekeepers can replicate these with wire netting from local hardware stores.

Many honeybees in Asia have the ability to protect their hive from intruding Giant hornets by scorching them. They wait for a hornet to enter their nest, then mob it by surrounding it completely with their bodies. Each honeybee vibrates its wings, and the combined warming of honey bee bodies raises the temperature in the center of the cluster to 122 degrees F (50 degrees C), killing the hornet. Carbon dioxide levels in the nest also increase during this process, which contributes to the hornet’s death.

Japanese honey bees swarm a Giant hornet, killing it with their body heat.

5. Are news stories about “murder hornets” overreacting?

Yes, very much so. In parts of Japan, people consider these hornets beneficial because they remove pests, such as harmful caterpillars, from crops. They are also thought to contain nutrients, and have been used as ingredients in Japanese food and some strong liquors. Some people believe the hornets’ essence has medicinal benefits.

People who live in Vancouver, Seattle or nearby should certainly take note of what these insects look like. They are 2 inches long or more, with a 3-inch wingspan, and have distinctly orange heads and broad striped orange and black-banded abdomens. That’s different from typical North American hornets, which have yellow or white bodies with black marks.

In the unlikely case that you see a Giant hornet in Washington state, do not try to remove nests yourself or spray hornets with pesticides. Cutting down trees to prevent nesting sites is also unnecessary, and can affect many other kinds of native wildlife, including beneficial insects that are needed for pollination and decomposition. Many native insects are declining globally, and it’s important to make sure these insects are not affected.

Instead, take a photo from a distance and report it to the Washington State Department of Agriculture. Photos are essential to verify that identifications are accurate.

Consider also uploading your images to iNaturalist, which is one of the primary sources for information on tracking wildlife. The images are archived and carry data, such as location, time of observance and the insect’s morphological features, that scientists can use for research.

Akito Y Kawahara, Associate Professor and Curator of Insects, Florida Museum of Natural History, University of Florida

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bottom line: What are Asian giant hornets? Do they deserve the nickname “murder hornets?” An entomologist says no.

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