Tag: Planets

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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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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Over The Past Nineteen Years, This Man Has Dedicated His Work To The Study Of Our Solar System

Dr. Franck Marchis is a senior planetary astronomer and chair of the exoplanet group at the Carl Sagan Center of the SETI Institute and Chief Scientific Officer and Founder at Unistellar.

He began full-time work at the Institute in June 2011 after leaving a joint position with Institute and the department of astronomy at University of California, Berkeley.

Marchis moved to the United States in October 2000 shortly after getting a Ph.D. from the University of Toulouse in France that he acquired while traveling around the world for his research and for the sake of exploration.

Over the past nineteen years, he has dedicated his work to the study of our solar system, specifically the search for asteroids with moons, using mainly ground-based telescopes equipped with adaptive optics (AO).

More recently he has been also involved in the definition of new generation of AOs for 8 -10 m class telescopes and future Extremely Large Telescopes.

He has also developed algorithms to process and enhance the quality of astronomical and biological images.




He is currently the collaboration manager of the Gemini Planet Imager Exoplanet Survey, which consists in imaging and characterizing Jupiter-like exoplanets using an extreme AO system designed for the Gemini South telescope.

Today, Marchis dedicates most of his energy to instruments capable of imaging and characterizing Earth-like exoplanets by being involved in education, public outreach, technology, and scientific investigations related to those ambitious projects both in the United States and in Europe.

Marchis is also involved in startups related to astronomy so he joined Unistellar as a Chief Scientific Officer and VR2Planets as a scientific advisor in 2017.

Marchis is a member of numerous science committees including the SETI Science council, the GPI steering Committee, the TMT Science Definition Team, PLOS One editor board, the Project Blue and the PLANETS Foundation Advisory board.

He has co-authored more than 380 scientific publications, trained numerous students, and served as a science consultant and interviewee for numerous documentaries and movies in English, French, and Spanish.

The asteroid (6639) was named Marchis in honor of his discovery of the first triple-asteroid system in 2007. He has been an affiliated Astronomer at Observatoire de Paris since 2003.

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Saturn’s Northern Pole Is Home To A Six-Sided Feature That Mystifies Scientists

This stunning new image reveals the massive hexagonal storm at Saturn’s North Pole, and its gigantic rings. Each latitudinal band represents air flowing at different speeds, and clouds at different heights, compared to neighboring bands.

At first glance, it looks like a serene planet.

However, stunning new images reveals the massive hexagonal storm at Saturn’s North Pole, and its gigantic rings.

In reality, the planet’s atmosphere is an ever-changing scene of high-speed winds and evolving weather patterns, punctuated by occasional large storms, Nasa says.

The latest image shows Saturn’s north polar region’s bands and swirls, which Nasa says somewhat resemble the brushwork in a watercolor painting.

Each latitudinal band represents air flowing at different speeds, and clouds at different heights, compared to neighboring bands.

Where they meet and flow past each other, the bands’ interactions produce many eddies and swirls.

The northern polar region of Saturn is dominated by the famous hexagon shape which itself circumscribes the northern polar vortex – seen as a dark spot at the planet’s pole in the above image – which is understood to the be eye of a hurricane-like storm.




Such collisions play a key role in the rings’ numerous waves and wakes, which are the manifestation of the subtle influence of Saturn’s moons and, indeed, the planet itself.

The long duration of the Cassini mission has allowed scientists to study how the atmosphere and rings of Saturn change over time, providing much-needed insights into this active planetary system.

It has long baffled astronomers, and now the strange hexagon at Saturn’s north pole has a new mystery.

The mysterious six-sided hexagon on Saturn’s North Pole has long captivated astronomer, and is thought to be nearly 20,000 miles (32,190 km) wide.

The hexagon is made of a band of upper-atmospheric winds which creates its shape.

A polar cyclone can be seen at its centre.

Recent natural colour images from NASA’s Cassini spacecraft show the changing appearance of Saturn’s north polar region between 2012 and 2016.

It shows a clear change from blue to gold – and nobody knows why.

The stunning image reveals the massive hexagonal storm at Saturn’s North Pole, and its gigantic rings. The rings, consist of countless icy particles, which are continually colliding.

Scientists are investigating potential causes for the change in color of the region inside the north-polar hexagon on Saturn.

The colour change is thought to be an effect of Saturn’s seasons.

In particular, the change from a bluish color to a more golden hue may be due to the increased production of photochemical hazes in the atmosphere as the north pole approaches summer solstice in May 2017,” Nasa said.

Researchers think the hexagon, which is a six-sided jetstream, might act as a barrier that prevents haze particles produced outside it from entering.

During the seven-year-long Saturnian winter, the polar atmosphere became clear of aerosols produced by photochemical reactions – reactions involving sunlight and the atmosphere.

This helps to explain why the hexagon is not influenced by seasonal changes, said the researchers.

It is hoped that by studying the movement of the hexagon it may be possible to understand more about the winds that are hidden beneath the stormy clouds in the gas giant’s upper atmosphere.

Speaking to Space.com, Professor Morales-Juberías said: “With a very simple model, we have been able to match many of the observed properties of the hexagon.

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Atomic Iron And Titanium In The Atmosphere Of The Exoplanet KELT-9b

To constrain the formation history of an exoplanet, we need to know its chemical composition.

With an equilibrium temperature of about 4,050 kelvin, the exoplanet KELT-9b (also known as HD 195689b) is an archetype of the class of ultrahot Jupiters that straddle the transition between stars and gas-giant exoplanets and are therefore useful for studying atmospheric chemistry.

At these high temperatures, iron and several other transition metals are not sequestered in molecules or cloud particles and exist solely in their atomic forms




However, despite being the most abundant transition metal in nature, iron has not hitherto been detected directly in an exoplanet because it is highly refractory.

The high temperatures of KELT-9b imply that its atmosphere is a tightly constrained chemical system that is expected to be nearly in chemical equilibrium and cloud-free, and it has been predicted that spectral lines of iron should be detectable in the visible range of wavelengths.

Here we report observations of neutral and singly ionized atomic iron (Fe and Fe+) and singly ionized atomic titanium (Ti+) in the atmosphere of KELT-9b.

We identify these species using cross-correlation analysis of high-resolution spectra obtained as the exoplanet passed in front of its host star.

Similar detections of metals in other ultrahot Jupiters will provide constraints for planetary formation theories.

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Mars Is Spectacular This Month – Here’s The Best Way To Spy The Red Planet

If you look at the sky tonight and spot a very bright star, it may well be a planet. Mars is the closest it has been to Earth for 15 years – and therefore the brightest.

Mars shines through reflected light,” says Robert Massey, the deputy executive director of the Royal Astronomical Society.

That means that when it’s closer to the Earth it appears brighter, because its apparent size is bigger.” It won’t be this visible again until 2035.

So, how best to see it? First, make sure tall trees or buildings are not obscuring the view. Ideally, you want a clear horizon. Then, look south.




It will be obvious, because it’s bright, it doesn’t twinkle and it has a distinct reddish tinge,” says Massey, who suggests Somerset, Devon and Dorset as good locations for spotting it.

The best Mars-gazing time is 1am, but it rises earlier in the evening.

You can see Mars with the naked eye, but a pair of binoculars would help,” says Massey. “If you have a small telescope, you may be lucky to see a polar ice cap.

If you are an amateur with good equipment, the details to look out for are two polar ice caps, mountains or volcanoes, and sunken, crater-like features. Massey suggests contacting your local astronomical society about public viewing events.

Hubble’s views of Mars at two recent oppositions

When is the best time to see Mars?

According to NASA, Mars Opposition begins Friday, July 27 around midnight.

Mars will be visible between Friday, July 27 and Monday, July 30, making its closest approach — 35.8 million miles to be exact — on Tuesday, July 31 at around 4 a.m. E.T.

Mars will be at its brightest Friday night due to an opposition surge that is affected by the planet’s angle of the sun — giving you the clearest view of the Red Planet.

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