Tag: Planets

Jupiter’s Great Red Spot Is Shrinking (Also, Jupiter Is Insane)

Jupiter’s Great Red Spot has been the biggest storm in the solar system for centuries. But lately, it seems to be shrinking… and nobody’s sure why.

So this video was supposed to just be about the Great Red Spot but honestly the more I looked into Jupiter, the more I was struck by how insane the planet is. So it kinda became about that.

Saturn Hasn’t Always Had Rings

Precise measurements of Cassini’s final trajectory have now allowed scientists to make the first accurate estimate of the amount of material in the planet’s rings, weighing them based on the strength of their gravitational pull.

That estimate about 40 percent of the mass of Saturn’s moon Mimas, which itself is 2,000 times smaller than Earth’s moon tells them that the rings are relatively recent, having originated less than 100 million years ago and perhaps as recently as 10 million years ago.

Their young age puts to rest a long-running argument among planetary scientists.

Some thought that the rings formed along with the planet 4.5 billion years ago from icy debris remaining in orbit after the formation of the solar system.

Others thought the rings were very young and that Saturn had, at some point, captured an object from the Kuiper belt or a comet and gradually reduced it to orbiting rubble.

The new mass estimate is based on a measurement of how much the flight path of Cassini was deflected by the gravity of the rings when the spacecraft flew between the planet and the rings on its final set of orbits in September 2017.




Initially, however, the deflection did not match predictions based on models of the planet and rings.

Only when the team accounted for very deep flowing winds in atmosphere on Saturn, something impossible to observe from space, did the measurements make sense, allowing them to calculate the mass of the rings.

They also calculated that the surface clouds at Saturn’s equator rotate 4 percent faster than the layer 9,000 kilometers (about 6,000 miles) deep.

That deeper layer takes 9 minutes longer to rotate than do the cloud tops at the equator, which go around the planet once every 10 hours, 33 minutes.

Militzer also was able to calculate that the rocky core of the planet must be between 15 and 18 times the mass of Earth, which is similar to earlier estimates.

The team, led by Luciano Iess at the Sapienza University of Rome, Italy, reported their results today in the journal Science.

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Pass it on: New Scientist

Something Massive Crashed into Uranus and Changed It Forever

This composite image, created in 2004 with Keck Observatory telescope adaptive optics, shows Uranus’ two hemispheres.

It turns out that Uranus is so weird because of a massive collision billions of years ago.

A new study confirms that this collision with a huge object — which was approximately twice the size of Earth — could have led to the planet’s extreme tilt and other odd attributes.

Uranus, the planet with the unforgettable name, is unique in a number of ways.

All of the planets in the solar system are spinning more or less in the same way … yet Uranus is completely on its side,” Jacob Kegerreis, the new study’s lead author and a researcher at Durham University’s Institute for Computational Cosmology in the U.K. said.

And this isn’t the only thing that makes the planet so strange.

Uranus also has a “very, very strange” magnetic field and is extremely cold, even though it “should” be warmer, according to Kegerreis.

In this study, Kegerreis and his team of astronomers seek to explain many of the planet’s odd features by attributing them to a collision with a massive, icy object about 4 billion years ago.

To better understand how the impact affected Uranus’ evolution, the team used a high-powered supercomputer to run a simulation of massive collisions — something that has never been done before.

This study confirms an older study that suggested Uranus’ significant tilt was caused by a collision with a massive object.

The researchers suspect that this object was probably a young protoplanet, made up of rock and ice. This collision is “pretty much the only way” that we can explain Uranus’ tilt, Kegerreis said.




 

Amazingly, Uranus retained its atmosphere after this impact.

The researchers think that this is because the object only grazed the planet, hitting it hard enough to change its tilt but not enough to affect its atmosphere, according to a statement from Durham University.

It’s likely that this type of event isn’t uncommon in the universe: “All the evidence points to giant impacts being frequent during planet formation, and with this kind of research, we are now gaining more insight into their effect on potentially habitable exoplanets,” Luis Teodoro, study co-author and researcher at the BAER/NASA Ames Research Center, said in the statement.

But this enormous object crashing into Uranus did more than just knock it into a new tilt.

According to this research, when the object hit Uranus, some of the debris from the impact may have formed a thin shell that continues to trap heat coming from the planet’s core.

This could at least partially explain why Uranus’ outer atmosphere is extremely cold.

The explosive results of a massive impact on Uranus

According to Kegerreis, this collision could also explain two other oddities about the tilted planet. First, it could explain how and why some of Uranus’ moons formed.

The researchers think that the impact could have knocked rock and ice into the young planet’s orbit — debris that later became some of Uranus’ 27 moons.

Additionally, they think that the collision could have altered the rotation of any moons that already existed at the time. Last year, a separate study also explored this aspect of the collision.

The researchers also suggest that the collision could have created molten ice and lumps of rock inside the planet, which tilted its magnetic field, according to the statement.

Following this study, the researchers hope to study this collision with even higher-resolution simulations to better understand Uranus’ evolution, according to Kegerreis.

He also noted that the team aims to study Uranus’ chemistry and the different ways that an impact like this could have affected its atmosphere.

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How the Mars Moon Phobos Got Its Grooves?

The weird linear grooves scoring the surface of the Mars moon Phobos were likely carved by boulders knocked loose by a giant impact, a new study suggests.

That impact created Phobos’ most notable feature — the 5.6-mile-wide (9 kilometers) Stickney Crater, which is about one-third as wide as the moon itself.

These grooves are a distinctive feature of Phobos, and how they formed has been debated by planetary scientists for 40 years,” study lead author Ken Ramsley, a planetary scientist at Brown University in Providence, Rhode Island, said in a statement.

We think this study is another step toward zeroing in on an explanation.

Mars has two tiny moons — Phobos and Deimos, both of which the Red Planet may have nabbed from the nearby asteroid belt long ago.




Phobos’ parallel grooves were first spotted in the 1970s by NASA’s Mariner and Viking missions. In the decades since, researchers have advanced many hypotheses to explain their origin.

For example, they may have been carved by material blasted off Mars by powerful impacts. Or they could be strain marks showing that Mars’ gravity is tearing Phobos apart.

Or bouncing, rolling boulders freed by the Stickney-causing impact could have created the grooves. This idea was first advanced in the late 1970s by researchers Lionel Wilson and Jim Head, the latter of whom is a co-author on the new study.

In the new work, the researchers used computer models to simulate how debris set in motion by the Stickney smashup may have traveled across Phobos’ surface.

The model is really just an experiment we run on a laptop,” Ramsley said in the same statement. “We put all the basic ingredients in, then we press the button and we see what happens.

What happened supports the rolling-boulder idea, study team members said. In the simulations, for example, rocks set in motion by the Stickney impact tended to travel on parallel paths, matching the observed groove patterns.

In addition, some of the simulated boulders traveled all the way around Phobos, rolling over the tracks of their fellow bounders. This could explain an oddity of the actual grooves — that some of them overlay one another.

There’s another puzzling aspect of the Phobos features — a weird “dead spot” free of grooves. But the new modeling work has an answer for that, too: The dead spot is a low-elevation area just beyond a slight “lip” of rock.

It’s like a ski jump,” Ramsley said. “The boulders keep going, but suddenly there’s no ground under them. They end up doing this suborbital flight over this zone.”

All in all, the work “makes a pretty strong case” that the “rolling-boulder model accounts for most if not all the grooves on Phobos,” Ramsley said.

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Pass it on: New Scientist

Planets Can Be Big, Small, But All Round

The eight planets in our solar system differ in lots of ways. They are different sizes. They are different distances from the sun. Some are small and rocky, and others are big and gassy.

But they’re all nice and round. Why is that? Why aren’t they shaped like cubes, pyramids, or discs?

Planets form when material in space starts to bump and clump together. After a while it has enough stuff to have a good amount of gravity.

That’s the force that holds stuff together in space. When a forming planet is big enough, it starts to clear its path around the star it orbits. It uses its gravity to snag bits of space stuff.

A planet’s gravity pulls equally from all sides. Gravity pulls from the center to the edges like the spokes of a bicycle wheel. This makes the overall shape of a planet a sphere, which is a three-dimensional circle.




Are they all perfect, though?

While all the planets in our solar system are nice and round, some are rounder than others. Mercury and Venus are the roundest of all. They are nearly perfect spheres, like marbles.

But some planets aren’t quite so perfectly round. Saturn and Jupiter are bit thicker in the middle. As they spin around, they bulge out along the equator. Why does that happen?

When something spins, like a planet as it rotates, things on the outer edge have to move faster than things on the inside to keep up.

This is true for anything that spins, like a wheel, a DVD, or a fan. Things along the edge have to travel the farthest and fastest.

Along the equator of a planet, a circle half way between the north and south poles, gravity is holding the edges in but, as it spins, stuff wants to spin out like mud flying off a tire.

Saturn and Jupiter are really big and spinning really fast but gravity still manages to hold them together. That’s why they bulge in the middle. We call the extra width the equatorial bulge.

Saturn bulges the most of all the planets in our solar system. If you compare the diameter from pole to pole to the diameter along the equator, it’s not the same.

Saturn is 10.7% thicker around the middle. Jupiter is 6.9% thicker around the middle. Instead of being perfectly round like marbles, they are like basketballs squished down while someone sits on them.

What about the other planets?

Earth and Mars are small and don’t spin around as fast as the gas giants. They aren’t perfect spheres, but they are rounder than Saturn and Jupiter.

Earth is 0.3% thicker in the middle, and Mars is 0.6% thicker in the middle. Since they’re not even one whole percentage point thicker in the middle, it’s safe to say they’re very round.

As for Uranus and Neptune, they’re in between. Uranus is 2.3% thicker in the middle. Neptune is 1.7% thicker. They’re not perfectly round, but they’re pretty close.

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NASA’s Revolutionary Planet-Hunting Telescope Kepler Runs Out of Fuel

NASA’s prolific Kepler Space Telescope has run out of fuel, agency officials announced on Oct. 30, 2018. The planet-hunting space telescope discovered thousands of alien worlds around distant stars since its launch in 2009.

The most prolific planet-hunting machine in history has signed off.

NASA’s Kepler space telescope, which has discovered 70 percent of the 3,800 confirmed alien worlds to date, has run out of fuel, agency officials announced last October 30.

Kepler can no longer reorient itself to study cosmic objects or beam its data home to Earth, so the legendary instrument’s in-space work is done after nearly a decade.

And that work has been transformative.

“Kepler has taught us that planets are ubiquitous and incredibly diverse,” Kepler project scientist Jessie Dotson, who’s based at NASA’s Ames Research Center in Moffett Field, California said.




“It’s changed how we look at the night sky.”

The announcement was not unexpected. Kepler has been running low on fuel for months, and mission managers put the spacecraft to sleep several times recently to extend its operational life as much as possible.

But the end couldn’t be forestalled forever; Kepler’s tank finally went dry two weeks ago, mission team members said during a telecon with reporters today.

This marks the end of spacecraft operations for Kepler, and the end of the collection of science data,” Paul Hertz, head of NASA’s Astrophysics Division, said during the telecon.

Prepping the Kepler spacecraft pre-launch in 2009.

Even though Kepler has closed its eyes, discoveries from the mission should keep rolling in for years to come.

About 2,900 “candidate” exoplanets detected by the spacecraft still need to be vetted, and most of those should end up being the real deal, Kepler team members have said.

A lot of other data still needs to be analyzed as well, Dotson stressed.

And Kepler will continue to live on in the exoplanet revolution it helped spark.

For example, in April, NASA launched a new spacecraft called the Transiting Exoplanet Survey Satellite (TESS), which is hunting for alien worlds circling stars that lie relatively close to the sun (using the transit method, just like Kepler).

Kepler’s death “is not the end of an era,” Kepler system engineer Charlie Sobeck, also of NASA Ames said. “It’s an occasion to mark, but it’s not an end.”

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Why Is Pluto No Longer A Planet?

In 2006, Pluto was voted out of the planetary club by members of the International Astronomical Union

But in 2006, it was relegated to the status of dwarf planet by the International Astronomical Union (IAU). So why was Pluto demoted?

Where did the controversy start?

Pluto was discovered in 1930 by US astronomer Clyde Tombaugh, who was using the Lowell Observatory in Arizona.

Textbooks were swiftly updated to list this ninth member in the club. But over subsequent decades, astronomers began to wonder whether Pluto might simply be the first of a population of small, icy bodies beyond the orbit of Neptune.

This region would become known as the Kuiper Belt, but it took until 1992 for the first “resident” to be discovered.

The candidate Kuiper Belt Object (KBO) 1992 QBI was detected by David Jewitt and colleagues using the University of Hawaii’s 2.24m telescope at Mauna Kea.




How did this change things?

Confirmation of the first KBO invigorated the existing debate. And in 2000, the Hayden Planetarium in New York became a focus for controversy when it unveiled an exhibit featuring only eight planets.

The planetarium’s director Neil deGrasse Tyson would later become a vocal figure in public discussions of Pluto’s status.

But it was discoveries of Kuiper Belt Objects with masses roughly comparable to Pluto, such as Quaoar (announced in 2002), Sedna (2003) and Eris (2005), that pushed the issue to a tipping point.

Eris, in particular, appeared to be larger than Pluto – giving rise to its informal designation as the Solar System’s “tenth planet“.

The discovery of other icy objects similar in size to Pluto forced a re-think by the IAU

Prof Mike Brown of the California Institute of Technology (Caltech), who led the team that found Eris, would later style himself as the “man who killed Pluto”, while deGrasse Tyson would later jokingly quip that he had “driven the getaway car”.

The finds spurred the International Astronomical Union to set up a committee tasked with defining just what constituted a planet, with the aim of putting a final draft proposal before members at the IAU’s 2006 General Assembly in Prague.

Under a radical early plan, the number of planets would have increased from nine to 12, seeing Pluto and its moon Charon recognised as a twin planet, and Ceres and Eris granted entry to the exclusive club. But the idea met with opposition.

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NASA’s New Planet Hunter Has Already Spotted Two Candidates For Earth-Like Alien Worlds

 

NASA’s Transiting Exoplanet Survey Satellite (TESS) has only been on the job less than two months, and already it’s ponying up the planet goods.

The exoplanet-hunting space telescope has found two candidate planets, and there are plenty more on the horizon.

The two candidate planets are called Pi Mensae c, orbiting bright yellow dwarf star Pi Mensae, just under 60 light-years from Earth; and LHS 3844 b, orbiting red dwarf star LHS 3844, just under 49 light-years away.

TESS took its first test observations on July 25 (and managed to get some pretty great snaps of a passing comet), and its first official science observations began on August 7.

However, it was observing a large swathe of sky from the moment it opened its eyes – four optical cameras – and both discoveries are based on data from July 25 to August 22.

So far, they are only candidate planets, yet to be validated by the final review process. If they pass that test, they’ll go down in history as TESS’s first two discoveries. Here’s what we know so far about them.

Both planets appear to be Earth-like and rocky, but neither is habitable according to our guidelines – both are too close to their stars for liquid water.

Pi Mensae c, the first planet announced, is a super-Earth, clocking in at just over twice the size of Earth. It’s really close to Pi Mensae – it orbits the star in just 6.27 days.




A preliminary analysis indicates that the planet has a rocky iron core, and also contains a substantial proportion of lighter materials such as water, methane, hydrogen and helium – although we’ll need a more detailed survey to confirm that.

It also has a sibling – it’s not the first object to be found orbiting Pi Mensae. That honour goes to Pi Mensae b, an enormous planet with 10 times the mass of Jupiter discovered in 2001.

It’s much farther out than Pi Mensae c, on an orbit of 2,083 days. LHS 3844 b is a little bit smaller, classified as a “hot Earth“.

It’s just over 1.3 times the size of Earth, and on an incredibly tight orbit of just 11 hours. Since the two are so close together, it’s highly likely the planet is blasted with too much stellar radiation to retain an atmosphere.

TESS does need a bit of time to collect enough data for identifying an exoplanet.

Like its predecessor Kepler, it uses what is known as the transit method for detection – scanning and photographing a region of the sky multiple times, looking for changes in the brightness of stars in its field of view.

When a star dims repeatedly and regularly, that is a good indication that a planet is passing between it and TESS.

By using the amount the light dims, and Doppler spectroscopy – that is, changes in the star’s light as it moves ever-so-slightly backwards and forwards due to the gravitational tug on the planet – astronomers can infer details about the planet, such as its size and mass.

 

Using this method, Kepler has discovered 2,652 confirmed planets to date between its first and second missions, located between 300 to 3,000 light-years away.

Kepler is still operational, but barely; it’s only a matter of time until it completely runs out of fuel.

TESS’s search is happening a lot closer, with targets between 30 and 300 light-years away – stars brighter than those observed by Kepler.

Thus, the exoplanets it identifies will be strong candidates to observe using spectroscopy, the analysis of light.

When a planet passes in front of a star, it has an effect on the light from the star, changing it based on the composition of its atmosphere (if it has one).

Ground-based observatories and the James Webb Space Telescope (once it launches in 2021) will have to make those follow-up observations.

Both papers are available on preprint resource arXiv. Pi Mensa c can be found here, and LHS 3844 b can be found here.

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Astronomers Just Found a Planet Where Star Trek’s Vulcan Was Predicted to Exist

So far, astronomers have identified thousands of exoplanets out there beyond the reaches of the Solar System, but only a rare few are the stuff of legend.

Such is the case with an Earth-like exoplanet, found orbiting a star called 40 Eridani A – Star Trek creator Gene Roddenberry’s preferred location for Vulcan, the home planet of Mr Spock.

Located around 16 light-years from Earth in the southern constellation of Eridanus, 40 Eridani A is part of a triple-star system.

Although it was never mentioned in the original TV series of Star Trek, it had been put forward as a proposed location for the planet by related literature.

In 1991, Roddenberry and three astronomers from the Harvard-Smithsonian Center for Astrophysics wrote a letter to Sky & Telescope magazine laying out their choice for Vulcan’s location, and why.

Based on the history of life on Earth, life on any planet around Epsilon Eridani would not have had time to evolve beyond the level of bacteria.




“On the other hand, an intelligent civilisation could have evolved over the aeons on a planet circling 40 Eridani. So the latter is the more likely Vulcan sun.

Epsilon Eridani does have one planet – an uninhabitable gas giant. Now astronomers on the University of Florida-led Dharma Planet Survey have found something that seems a bit more habitable orbiting 40 Eridani A.

More precisely, it’s an object known as a super-Earth – a rocky planet around twice the size of Earth, orbiting 40 Eridani A just inside the system’s habitable zone – not too hot and not too cold. It completes one orbit every 42 (Earth) days.

So life on the planet isn’t unfeasible.

The aim of the Dharma Planet Survey, using the 50-inch Dharma Endowment Foundation Telescope (DEFT) on Mount Lemmon in Arizona, is a dedicated survey to find low-mass planets orbiting bright, nearby stars.

It uses the radial velocity method – detecting the very slight wobble in a star’s position due to the gravitational pull of an exoplanet.

The candidate exoplanet, named HD 26965b (but we’ll probably call it Vulcan, obviously), is the first super-Earth found in the survey.

And if you’re in the southern hemisphere, you can even go outside and look for it.

“Now anyone can see 40 Eridani on a clear night and be proud to point out Spock’s home.”

The research has been published in the Monthly Notices of the Royal Astronomical Society.

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