Space: The Final Frontier

[CaaC (John)+]

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Largest-ever comet cometh! But have no fear, it won’t come near

The four billion-year-old comet has been falling toward the Sun for over one million years.

Astronomers have detected a comet hurtling toward Earth at around 10 kilometres a second. And it’s the largest comet ever observed, weighing in at 500 trillion tonnes. But don’t lock yourselves away in your bunkers just yet. This comet will only get as close as 1.6 billion kilometres from the Sun in 2031, so we’re in no danger. This time.

Comets are the icy remnants of the period of planet formation in the early solar system. They are now thought to exist in the hypothesised Oort Cloud – a vast reservoir of comets flung billions of kilometres beyond the farthest planets encircling the Sun. When observed, comets have a characteristic tail, sometimes stretching millions of kilometres, made of ice and gas. But at the head of every comet is a ball of ice and dust.

The gargantuan comet headed our way is called Comet C/2014 UN271. The four billion-year-old comet has been falling toward the Sun for well over one million years. It was discovered by accident in 2010 by astronomers Pedro Bernardinelli and Gary Bernstein when it was nearly five billion kilometres from the Sun; they came across it when studying archival images from the Dark Energy Survey at the Cerro Tololo Inter-American Observatory in Chile.

A new study of the comet, published in the Astrophysical Journal Letters, was co-authored by Professor David Jewitt of the University of California Los Angeles (UCLA), US. “This comet is literally the tip of the iceberg for many thousands of comets that are too faint to see in the more distant parts of the solar system,” Jewitt says. “We’ve always suspected this comet had to be big because it is so bright at such a large distance. Now we confirm it is.”

“This is an amazing object, given how active it is when it’s still so far from the Sun,” says lead author Man-To Hui from the Macau University of Science and Technology. “We guessed the comet might be pretty big, but we needed the best data to confirm this.”

NASA Hubble Space Telescope observations were needed to see the solid “nucleus” of the comet behind the huge dusty shield enveloping it. The researchers found the comet is at least 130km in diameter.

Hui and Jewitt’s team used Hubble to take five photos of the comet on January 8, 2022. Though too far away to be seen directly, the team identified the bright spot in the images as the comet’s nucleus. Using a computer model, Hui and this team were able to compensate for the surrounding dust to resolve the solid nucleus.

Combining their data with earlier observations by the Atacama Large Millimetre/submillimetre Array in Chile, the researchers narrowed down the diameter and reflectivity of the comet’s nucleus. In addition to its massive size – 50 times larger than any other known comet – the comet is darker than predicted. “It’s big and it’s blacker than coal,” says Jewitt.

The Oort Cloud is thought to contain trillions of comets, with its inner edge expected to lie somewhere between 2,000 and 5,000 times the distance from the Sun to Earth. Its outer edge may stretch to a quarter the distance from our Sun to the Alpha Centauri system, the nearest stars to us.

Other deep sky surveys and observations of comets like Comet C/2014 UN217 will help astronomers understand the role that the Oort Cloud plays in the evolution of the solar system.

https://cosmosmagazine.com/space/comet-billion-oort-cloud/

 

 

 

Edited April 18, 2022 by CaaC (John)
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[nudge+]

Venus, Mars, Saturn and Jupiter are lining up in a rare celestial event at the moment - quite a spectacular view! Will peak tomorrow, and then in the next few days the Moon will join them, too (should be visible around April 23-29). Hope for clear skies...

[CaaC (John)+]

1 hour ago, nudge said:

Venus, Mars, Saturn and Jupiter are lining up in a rare celestial event at the moment - quite a spectacular view! Will peak tomorrow, and then in the next few days the Moon will join them, too (should be visible around April 23-29). Hope for clear skies...

Will have another look later when it gets dark, hopefully if it is a clear night, fingers crossed 

[nudge+]

Just now, CaaC (John) said:

Will have another look later when it gets dark, hopefully if it is a clear night, fingers crossed 

It's visible shortly before sunrise only

[CaaC (John)+]

1 minute ago, nudge said:

It's visible shortly before sunrise only

Then I will be an early bird and have a peek 

[CaaC (John)+]

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Make Uranus mission your priority, Nasa told

The US space agency Nasa should prioritise a mission to Uranus, an influential panel of scientists says.

The "ice giant" is the seventh planet in our Solar System, orbiting the Sun 19 times further out than the Earth.

It's only ever been visited once before, in a brief flyby by the Voyager-2 probe in 1986.

Researchers think an in-depth study of Uranus can help them better understand the many similarly sized objects now being discovered around other stars.

The recommendation is made in a document published by the US National Academies of Sciences, Engineering, and Medicine (NAS).

Known as a "decadal survey", it is the summation of what the American research community thinks are the big planetary science questions right now and the space missions required to answer them.

Nasa has broadly followed the recommendations of previous National Academies reports.

The last planetary decadal survey, published in 2011, had as its two top priorities a rock-collection mission to Mars, which became the Perseverance rover, now on the surface of the Red Planet; and a mission to Jupiter and its moon Europa, which is currently being prepared for launch in 2024. This is called the Europa Clipper spacecraft.

FULL REPORT

 

[CaaC (John)+]

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Earthly comparison hints at shallow liquid water on Jupiter’s moon

Similarities between Europa and Greenland ice sheets provide the clues.

Researchers have revealed new insight into the geology of Jupiter’s moon Europa, described by NASA as one of the most promising locations in our solar system for present-day extraterrestrial life.

Scientists strongly suspect that Europa, one of an estimated 79 moons orbiting the planet Jupiter, harbours liquid water in the form of a large saltwater ocean beneath a frozen icy crust. Europa’s ice “shell” is estimated to be 20-30 kilometres thick.

In a paper published today in Nature Communications, a research team led by Riley Culberg of Stanford University, US, presents evidence that shallow liquid water also exists much closer to Europa’s surface, within the ice shell.

Europa’s ice shell is covered in landforms called “double ridges” – consisting of two ridges of ice that are nearly symmetrical on either side of a shallow trough – up to hundreds of kilometres long.

In the new study, the researchers investigated a double ridge found on Earth in the ice sheet over northwest Greenland. The double ridge is very similar in shape to those found on Europa.  

Using surface elevation and radar sounding data, the team found that the Greenland double ridge was probably formed by shallow liquid water within the ice sheet gradually refreezing, becoming pressurised and eventually fracturing the ice.

This finding implies that a similar mechanism might cause the double ridges on Europa as well – although there are some differences. In Greenland, the regions of shallow liquid water are formed by drainage of meltwater from the surface. On Europa, the liquid water might instead be injected from below, originating from the moon’s subsurface ocean.

The study suggests that shallow liquid water may be more important to shaping Europa’s surface than previously recognised.

“If this mechanism controls double ridge formation at Europa, the ubiquity of double ridges on the surface implies that liquid water is and has been a pervasive feature within the brittle lid of the ice shell,” Culberg and colleagues write.  

With NASA’s Europa Clipper mission scheduled to be launched in October 2024, we’ll no doubt learn much more in the coming decades about the geology of this intriguing moon – and its potential to harbour life.

https://cosmosmagazine.com/space/astronomy/shallow-liquid-water-europa/

 

[CaaC (John)+]

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Edited April 25, 2022 by CaaC (John)

[CaaC (John)+]

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The micronova: small but explosive

Astronomers discover new type of cosmic explosion called a ‘micronova’.

This artist’s impression shows a two-star system where micronovae may occur.

When a star reaches the end of its life it dies in the most spectacular way, through an incredibly powerful and luminous explosion known as a supernova. These occur every 200–400 years and are visible from the Earth’s surface.

Using the European Southern Observatory’s Very Large Telescope (ESO VLT), a team of astronomers have now discovered a smaller type of cosmic explosion, called the micronova. Their work has been published in Nature.

Excitingly, the discovery of the micronova has improved our knowledge of nuclear reactions. During a supernova a white dwarf in a two-star system can steal material, especially hydrogen, from its nearby companion. As this gas connects to the hot surface of the white dwarf, it triggers the hydrogen atoms to fuse into the helium, causing a thermonuclear explosion across the entire surface of the star.

“Such detonations make the entire surface of the white dwarf burn and shine brightly for several weeks,” explains co-author Dr Nathalie Degenaar, an astronomer at the University of Amsterdam, in The Netherlands).

In comparison, micronovas are a similar type of explosion but on a smaller and faster scale. They occur when white dwarfs with strong magnetic fields siphon material towards the star’s magnetic poles, causing hydrogen fusion to happen in a localised way.

“This leads to micro-fusion bombs going off, which have about one millionth of the strength of a nova explosion, hence the name micronova,” says study co-author Professor Paul Groot, an astronomer at Radboud University, The Netherlands.

“What’s incredible is that these bursts are very fast; they only last 10 hours to half a day and then are gone,” says Dr Simone Scaringi of Durham University, UK, who led the discovery. This is compared to supernovas, which can be visible for months.

The discovery of these micronova events challenge our understanding of stellar explosions, where novae may occur more frequently and in more diverse ways, than previously thought.

“It just goes to show how dynamic the Universe is,”says Scaringi. “These events may actually be quite common, but because they are so fast they are difficult to catch in action.”

https://cosmosmagazine.com/space/astrophysics/the-micronova-small-but-explosive/

 

Edited April 25, 2022 by CaaC (John)
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[CaaC (John)+]

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Jupiter and Venus will “kiss” tonight

You can see a rare planetary alignment – if you get up early.

May is the month of love. So it’s fitting that it should start with two planets surreptitiously “kissing”, in the early hours of Sunday morning.

If you get up early this Sunday, 1 May, you’ll be able to spot a rare planet alignment. Saturn, Mars, Venus and Jupiter will appear from the Earth to be in a straight line.

Jupiter and Venus will get so close together that they’ll overlap – looking like one planet, or, according to astrophysicist Dr Brad Tucker from the Australian National University, like they’re “kissing”.

“Venus and Jupiter have been moving closer together over the past several weeks, so this romantic spark between them has been brewing for some time,” says Tucker.

Between 4:30 AM AEST and sunrise will be the best time to view the planets. They’ll be visible to the naked eye in the eastern skies.

“On the morning of Sunday 1 May AEST, they will appear to be so close that they’ll look like one object, or appear as if they are kissing. Similar to what Jupiter and Saturn did at the end of 2020.”

The additional alignment of Saturn and Mars makes this a one in a thousand year event.

“Although Venus and Jupiter get close to one another every few years, this time there is also Mars and Saturn in the mix which is pretty rare, watching from afar like the creepy neighbour next door,” says Tucker.

You shouldn’t need any special equipment to spot the planets. Apps like SkyView, Night Sky and Star Walk 2 can help you find the right dots of light.

“If you have a telescope, a pair of binoculars or a decent camera, then you’ll get an even better view,” points out Tucker.

•  Winds of Jupiter’s Great Red Spot are speeding up

Cosmos contacted both Jupiter and Venus for comment, but neither responded. The thrill of new love is distracting.

Saturn, however, told us that it’s a good thing that Mars is also present.

“Being the third wheel is awkward,” says Saturn. “But being the fourth wheel is manageable.

“If they need some rings, they can hit me up.”

https://cosmosmagazine.com/space/astronomy/planets-align-and-overlap/

 

Edited April 30, 2022 by CaaC (John)
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[Bluewolf]

[nudge+]

1 minute ago, Bluewolf said:

That's totally not the protomolecule

I've got video feed, too.

[CaaC (John)+]

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Spotted: a Tatooine-like exoplanet orbiting two stars

New, cheaper method shows planet-spotting proof of concept

Happy Star Wars Day! And May the 4^th be with you.

Like Tatooine – the home world of Anakin and Luke Skywalker – a rare exoplanet with its own binary sunset (but in our galaxy, the Milky Way) was spotted by astronomers earlier this year using a ground-based telescope.

We all know that the best films come in trilogies, like Star Wars and A Spacetime Trilogy with Jared Kaplan – a 2021 SCINEMA International Film Festival entry. In the series, Jared Kaplan, theoretical physicist at Johns Hopkins University in the US, looks to black holes, gravity, and even a dazzle of zebras, to examine profound and whimsical questions about spacetime and our universe.

Watch the full trilogy here

A rare exoplanet orbiting two stars at once has been spotted by researchers using a ground-based telescope, in a first-of-its kind demonstration that less expensive, on-the-ground methods could be used to find such rare planets. 

The exoplanet, Kepler-16b, is 245 lightyears from Earth and, just like the home worlds of both Luke Skywalker (Tatooine) and Doctor Who (Gallifrey), has two sunsets a day as it drifts around its twin stars. It was first discovered 10 years ago by NASA’s Kepler satellite.

Kepler-16b orbits two stars, and those two stars orbit one another. Pairs of stars that orbit one another, known as binary systems, are not rare in themselves – estimates range, but CSIRO predicts possibly up to 85% of all stars are in binary systems. But circumbinary planets (planets that orbit these twin stars) are rare, and before Kepler-16b we only knew of ten.

In fact, scientists aren’t sure how circumbinary planets can come to exist. Typically, planets are formed from the mass of dust and gas that surrounds a young star, known as the protoplanetary disc. But this process may not be possible in a binary system.

“That’s because the presence of two stars interferes with the protoplanetary disc, and this prevents dust from agglomerating into planets, a process called accretion,” explains lead researcher Amaury Triaud, from the University of Birmingham. “Using this standard explanation it is difficult to understand how circumbinary planets can exist”

The team observed the exoplanet using a telescope based at the Observatoire de Haute-Provence, in France. They were able to detect the exoplanet using the radial velocity method, observing the change in the velocity of a star as a planet orbits around it. 

The researchers say this demonstration is important, because it shows we can detect exoplanets using cheaper and more efficient methods. They say the radial velocity method is more sensitive to additional planets in a system, and can also measure the mass of a planet.

They hope to continue the search for more circumbinary planets, and hopefully answer the pressing question of how these planets form. 

“The planet may have formed far from the two stars, where their influence is weaker, and then moved inwards in a process called disc-driven migration,” says Triaud. “Or, alternatively, we may find we need to revise our understanding of the process of planetary accretion.”

Isabelle Boisse, from the University of Marseille, is the scientist in charge of the SOPHIE instrument used to collect the data.

“Our discovery shows how ground-based telescopes remain entirely relevant to modern exoplanet research and can be used for exciting new projects,” Boisse says. “Having shown we can detect Kepler-16b, we will now analyse data taken on many other binary star systems, and search for new circumbinary planets.”

https://cosmosmagazine.com/space/astronomy/exoplanet-orbits-two-stars/

 

Edited May 4, 2022 by CaaC (John)
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Edited May 6, 2022 by CaaC (John)
Cock up

[CaaC (John)+]

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This weekend’s meteor shower: Eta Aquariid

Halley’s comet puts on a show more than once every 76 years.

If you’re willing to get up early this weekend, you have a good shot of spotting one of the best meteor showers of the year.

Meteor showers happen when the Earth passes through patches of debris in space, left behind by comets. These particles burn up in the Earth’s atmosphere, creating a scattering of shooting stars.

Because this debris doesn’t move much relative to Earth’s orbit, meteor showers tend to occur at the same points each year.

This weekend, as Earth travels through the orbit of Halley’s Comet, we’ll be expecting to see some shooting stars in both hemispheres, but particularly in the South. The full shower goes from 4 May – 11 May, but best viewing for Australia will be early in the morning of Saturday 7 May. Sunday and Monday mornings should also provide a good view if it’s cloudy tomorrow.

You should set aside at least half an hour to view the meteor shower, which will be visible from roughly 2AM (local times) across the whole country until dawn.

Don’t use a telescope (unless you also want to check out four aligning planets, which is still happening). Instead, look at the whole sky (the wide portion to the north-east is best for this), let your eyes adjust to the darkness…and wait. (Wear something warm.) You might not see anything for 10 minutes, then several at once.

The meteors will appear all over the sky, but you’re likely to spot the highest number coming from the constellation Aquarius – hence the name. Apps like SkyView, Night Sky and Star Walk 2 can help you find it.

https://cosmosmagazine.com/space/astrobiology/eta-aquariid-meteor-shower-australia/

 

Edited May 6, 2022 by CaaC (John)
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[CaaC (John)+]

4 hours ago, CaaC (John) said:

The meteors will appear all over the sky, but you’re likely to spot the highest number coming from the constellation Aquarius – hence the name. Apps like SkyView, Night Sky and Star Walk 2 can help you find it.

[CaaC (John)+]

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Hubble has found a star hiding behind the corpse of a star, adding weight to an explosive theory

Companion star that witnessed – and siphoned from – a supernova.

The Hubble Space Telescope has found a star implicated in the death of its partner.

An international team of astronomers used observations from the telescope to confirm the existence of a companion star to a supernova. The discovery clears up a mystery about supernova chemistry, as well as helping researchers to understand how giant binary stars work.

Supernovae are vast explosions in space, created at the end of a star’s life. They carry layers of elements around them, with hydrogen gas at the very edge. If there’s no hydrogen around a supernova – as is the case with supernova 2013ge – something must have been stripping it away pre-explosion.

So what might be siphoning the hydrogen? Researchers say it’s a companion star that’s been hidden by the supernova’s brightness.

“This was the moment we had been waiting for: finally seeing the evidence for a binary system progenitor of a fully stripped supernova,” says Ori Fox, an astronomer at the Space Telescope Science Institute in Baltimore, US, and lead author on a paper describing the research, published in The Astrophysical Journal Letters.

The researchers used Hubble’s Wide Field Camera 3 to study the region of supernova 2013ge in ultraviolet light, as well as examining archived images of the supernova fading – as it did from 2016 to 2020.

A nearby source of ultraviolet light stayed bright as the supernova faded – leading researchers to suspect a second star.

“In recent years many different lines of evidence have told us that stripped supernovae are likely formed in binaries, but we had yet to actually see the companion,” says co-author Maria Drout, a researcher at the University of Toronto, Canada.

“So much of studying cosmic explosions is like forensic science – searching for clues and seeing what theories match. Thanks to Hubble, we are able to see this directly,” Drout adds.

The researchers say that this adds weight to the growing theory that most massive stars form as binary systems.

Based on the Hubble imagery, the companion star was “jostled” but not otherwise disturbed by 2013ge’s supernova.

It is, however, equally massive – and probably headed for the same fate as its partner. One day, it will explode and form its own supernova, before collapsing into a neutron star or black hole.

From there, it may be flung away from its partner – which the researchers say would explain why we sometimes see solitary supernovae.

Alternatively, it could continue to orbit its dead companion, eventually merging and shooting out gravitational waves.

But it’ll take a little patience to find out. “With the surviving companion of SN 2013ge, we could potentially be seeing the prequel to a gravitational wave event, although such an event would still be about a billion years in the future,” says Fox.

The researchers will be looking for other bereaved supernova companion stars with the Hubble Space Telescope’s help.

“There is great potential beyond just understanding the supernova itself. Since we now know most massive stars in the universe form in binary pairs, observations of surviving companion stars are necessary to help understand the details behind binary formation, material-swapping, and co-evolutionary development,” says Fox.

“It’s an exciting time to be studying the stars.”

https://cosmosmagazine.com/space/astrophysics/supernova-witness-hubble/

 

[Bluewolf]

This is proper creepy... sounds like it came straight from the horror 'Event Horizon' 

Science. - 9GAG

[nudge+]

27 minutes ago, Bluewolf said:

This is proper creepy... sounds like it came straight from the horror 'Event Horizon' 

Science. - 9GAG

Definitely the souls of trapped spacefarers...

[Bluewolf]

5 minutes ago, nudge said:

Definitely the souls of trapped spacefarers...

Space Sirens suckering weary travellers ships in no doubt until they reach the point of no return.. Might explain why we have not been visited yet.. 

[nudge+]

3 minutes ago, Bluewolf said:

Space Sirens suckering weary travellers ships in no doubt until they reach the point of no return.. Might explain why we have not been visited yet.. 

New idea for a book  

[Bluewolf]

7 minutes ago, nudge said:

New idea for a book  

The Space Sirens of Andromeda... 

[nudge+]

3 minutes ago, Bluewolf said:

The Space Sirens of Andromeda... 

Sounds like the perfect title for a campy 70s TV show  

[Bluewolf]

1 minute ago, nudge said:

Sounds like the perfect title for a campy 70s TV show  

Better a decent story told in Heavy Metal Magazine... 

[nudge+]

5 minutes ago, Bluewolf said:

Better a decent story told in Heavy Metal Magazine... 

Oooooh yes, definitely has Heavy Metal vibes...