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Red red moon!

December 21, 2010 4 comments

photograph of dec 21 lunar eclipse

Cornelis Dutoit, an engineer at Goddard Space Flight Center and president of our amateur astronomy club, took this bloody red image of the moon at about 3 a.m. this morning from home. We had great luck here in Maryland, with good clear skies for lunar eclipse viewing. Cornelis recounts his experience…

At first it seemed that everything was going wrong. I first struggled to get my scope balanced with a new camera adapter, and then when I went through the motions of getting the telescope aligned, its batteries died on me! I got new batteries installed (AA size in the C-size holders) just as the eclipse was starting. After that everything went fine, and even the slight wind died down. Clouds appeared on the Southern horizon but did not get near the moon. I waited till 3 a.m., about 20 minutes after the moon was covered completely but not quite at the center of the eclipse, when I finally decided that I had enough cold exposure for the night… My first pictures were taken with 1/250th of a second exposure, and the last was done with 15 second exposure, which shows that the moon dimmed in the order of 4000 times or more!

To take the picture, he used a Panasonic Lumix DMC FZ8 camera mounted on a 42mm eyepiece with a Meade 8-inch f10 Schmidt Cassegrain telescope, 15-second exposure time.

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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.

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NASA Goddard scores six spots in Discover Magazine's Top 100 Science Stories of 2010!

December 17, 2010 Leave a comment

Discover Magazine revealed their Top 100 Science Stories of 2010, and Six NASA Goddard stories made the countdown. It reminds us that despite NASA being most closely identified or “branded” as the people who put people on the moon, we are as much a scientific institution as anything else. Here are the winners.

#100: Portrait of a Violent Star

#98: Roaming Rocks of Death Valley

#83: Mammoth Star Is the Biggest One Ever Seen

#76: What Lies Beyond the Edge of the Universe

#55: First Peek at the Solar System’s Outer Edge

#28: The Incredible Shrinking Moon

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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.

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That Was The Week That Was, December 13-17, 2010. . . A Digest of Goddard People, Science, & Media, PLUS Historical Tidbits and Our Best Stuff in the Blogpodcastotwitterverse

December 17, 2010 Leave a comment



photo of goddard employeesMONDAY December 13: Hey good looking! See a week in the life of Goddard people: the slideshow.

Heat islands: Why summer land surface temperatures are rising in the Northeast.

NASA Blueshift’s Weekly Awesomeness Round Up spotlights SDO’s latest stunning solar images, sneak attacks from the sun, an update on its coverage of alleged “arsenic-based life,” the latest technological tour-de-force from the Webb Telescope project, and other astro-news of the week.


artist concept of mariner 2TUESDAY December 14: On this day in 1962, Mariner 2 passes within 22,000 miles of Venus and transmits data back to Earth, becoming the world’s first successful interplanetary spacecraft. Mariner 2 recorded the planet’s temperature for the first time, revealing its very hot atmosphere of about 500 degrees Celsius (900 degrees Fahrenheit). The spacecraft’s solar wind experiment was the first to measure the density, velocity, composition and variation over time of the solar wind. . .On this same day in 1978, the Pioneer Venus Orbiter went into orbit around Venus and relayed data until its systems failed.


image of supernova remnant shellHungry: Research by Goddard’s Marc Imhoff and colleagues finds that humans are consuming an increasing amount of the Earth’s total annual land plant production.

Pushing it: humans are using an increasing amount of the Earth’s total land plant production each year for food, fiber, building and packaging materials and biofuels.

Hubble bubble: space observatory sees supernova shell that looks like an ornament.


illumination map of the moon south polar areaWEDNESDAY December 15: New illumination map of the moon’s south pole shows which areas are dark and which are in the light.

Keeps on ticking: Today, Mars Odyssey becomes the all-time longest-running spacecraft at Mars. Launched in 2001, the probe begins its 3,340th day in Martian orbit at 8:55 p.m. EST on Wednesday to break the record set by NASA’s Mars Global Surveyor, which orbited Mars from 1997 to 2006.

No way! Goddard science report says amino acids found in an “impossible” place.

Losing it: Why West Antarctica ice is shrinking.


THURSDAY December 16, 2010: Behold the chirping, pulsating Norwegian aurora on the What On Earth blog this week.

In a new video, meet Carrie Anderson, a member of the NASA team probing Titan with the CIRES instrument.




FRIDAY December 17: NASA Earth Observatory’s Image of the Day spotlights a land surface temperature map showing that the first week of December was exceptionally cold in northern Europe and the eastern United States. Blame it on the “Arctic Oscillation.”

It’s a whole new moon: Lunar Reconnaissance Orbiter’s LOLA instrument is charting a exquisitely detailed — and colorful — new view of our luminous natural satellite.


image of moon made with lola instrument data

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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.

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How to rip a moon apart

December 14, 2010 2 comments

artist concept of ice particles in saturn rings


We know that Saturn’s rings are ice particles orbiting the planet like a zillion tiny moons. But we’re not so sure how they got there. Surprised?

This week, a researcher at the Southwest Research Institute in Colorado, Robin Canup, published a new and intriguing hypothesis for what built Saturn’s rings as well as its inner moons. In a nutshell, Canup says multiple icy moons spiraled to their doom early in Saturn’s history, leaving behind the ice and rock that formed the rings and Saturn’s small inner moons.

Canup’s idea solves a few key problems for Saturn ring theorists. For more details, see the press release or a story by Discovery News writer Irene Klotz.

It’s hard to imagine a moon perhaps the size of Titan — around 5,150 kilometers (3,200 miles) across — getting torn apart. But it can happen, and the cause of it all is called tidal disruption.

Terry Hurford is a planetary scientist at Goddard who studies tidal disruption as it relates to Jupiter’s moon Europa and Saturn’s moon Enceladus. Gravitational tides alternately stretch and compress those bodies, causing cracking at the surface and interior heating.

On Europa, the degree of distortion is about 1 kilometer (0.6 miles) in extent. It’s not as clear about Enceladus, but Hurtford roughly estimates it could be around 500 meters.

But if a moon strays too close to its planet, the tides can stretch it to the breaking point. The threshold is known as the Roche limit. Once a satellite gets within that distance to its planet, the planet’s gravity is in charge and the moon literally can’t hold itself together.

“The body gets more and more distorted tidally,” Hurford explains. “The gravity from Saturn makes it more like a football shape, where you have this kind of a point of the football pointed toward Saturn. As you get closer, this distortion can grow really large. If you get close enough, you can distort the body so much that it no longer can hold onto its mass.”

And that’s exactly what Canup shows in her new computer simulation. Multiple moons stray inside Saturn’s Roche limit. Tidal flexing — the same thing that today occurs on Europa and Enceladus — melts the moon’s watery ices and separates them from rocky material. Eventually the ice gets stripped off entirely to form the rings and inner moons, and the rocky stuff plummets into Saturn.

Pretty dramatic! And it’s intriguing to think that Saturn might have once had several large moon, not just one. I think they deserve to at least be named, these lost satellites of Saturn.

How about: “Going, “Going,” and “Gone”?


Tidal Disruption of a Moon
[These illustrations appear in the Wikipedia entry for “Roche limit” and were created by Theresa Knott of English Wikipedia. The illustration shows a top view of a planet and its moon.]


illustration of tidal disruptionFar from the planet’s Roche limit (curved white line), the moon’s gravity molds it into a near-perfect sphere.





illustration of tidal disruptionAs the moon approaches the Roche limit, the planet’ s powerful gravity stretches and distorts the smaller satellite.





illustration of tidal disruptionAt the Roche limit, tidal forces overwhelm the moon’s own gravity, tearing the satellite into pieces.





illustration of tidal disruptionParticles inside the Roche limit orbit faster than those outside the limit. This causes the particles to spread out and form rings.
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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.

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That Was The Week That Was, December 5-10, 2010. . . A Digest of Goddard People, Science, & Media, PLUS Historical Tidbits and Our Best Stuff in the Blogpodcastotwitterverse

December 10, 2010 Leave a comment

image of Chatham island plankton bloomSUNDAY December 5: The Smithsonian AirSpace blog features Robert Goddard, the namesake of our center.

Ocean bloom: A large springtime bloom colored the ocean near the Chatham Islands, New Zealand. The Aqua satellite captured a stunning image of this colorful event today.


MONDAY December 6: On the NASA What On Earth blog, a new “what on Earth is that?” puzzler to solve.

Northern jewel: The Arctic National Wildlife Refuge Turns 50 today. Here’s NASA Earth Observatory’s Image of the Day: a NASA/Aqua portrait of this unique wildlife area.


photo of goddard employees at film festivalTUESDAY December 7: On this day 15 years ago, the Galileo spacecraft released a probe into Jupiter’s atmosphere. Also today, in 2001, NASA launched the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) mission. TIMED is studying a region of Earth’s upper atmosphere that has never been the subject of a comprehensive, long-term scientific investigation.

Sneaky sun: Harvard scientists use STEREO spacecraft to count space weather “sneak attacks” from sun.

Snowy isle: NASA’s Aqua satellite images a snow-blanketed Ireland after a powerful winter storm hit much of northern Europe in early December

Oh Snap! A Week in the Life of Goddard: Here are some of the more than 700 photographs submitted by Goddard employees, documenting life and work “on Center.”

Cool finding: Computer model shows tree growth could help cool a world with doubled atmospheric carbon dioxide levels.


NASA image of the sun captured December 8, 2010WEDNESDAY December 8: Solar Dynamics Observatory snaps the spaced out smiley face of our home star.

Goddard filmfest: Employees use ballots to vote for their favorite NASA science and mission videos.

Diamond planet: Scientists announce discovery of a carbon-rich, possibly diamond-littered world previously hypothesized by Goddard exoplanet researcher Marc Kuchner and others.

Good attitude: Read a Q&A with Goddard’s Melissa Vess, an engineer who worked on the attitude control system for Solar Dynamics Observatory mission.

Midwest mantle: Snow covers the U.S. Midwest in this new Terra satellite image.

Deadly flood: Goddard scientists use their satellite fleet to map the heavy rainfalls in Venezuela, Colombia, and Costa Rica in late November and early December 2010 that killed more than 190 people.


artist concept of carbon-rich planetsTHURSDAY December 9: Try to focus: A new video takes viewers behind the Webb’s mirrors to investigate “actuators,” one component that will help Webb focus on some of the earliest objects in the universe.


FRIDAY December 10: On this day in 1974, NASA launches Helios 1, a joint project of Goddard Space Flight Center and the Federal Republic of Germany — NASA’s first such project with that nation.

What’d he call it? On the NASA Blueshift blog, Goddard astrophysicist Koji Mukai writes about the mystery of Hanny’s Voorwerp.
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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.

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WASP-12b: Shine on you crazy diamond planet

December 8, 2010 2 comments

Artist's concept of a carbon planet with a tar covered surface. A meteor impact has exposed a diamond layer in the planet's interior. For permission to reproduce this figure, please contact Lynette R. Cook, lynette@spaceart.org. Credit: Lynette Cook (extrasolar.spaceart.org)

In this artist's concept of a tar-covered carbon planet, a meteor impact has exposed a diamond layer in the planet's interior. For permission to reproduce this figure, please contact Lynette R. Cook at lynette@spaceart.org. Credit: Lynette Cook (extrasolar.spaceart.org)

“There is no use trying, said Alice; one can’t believe impossible things. I dare say you haven’t had much practice, said the Queen. When I was your age, I always did it for half an hour a day. Why, sometimes I’ve believed as many as six impossible things before breakfast.”

This just in from our Department of Impossible Things: carbon-soaked planets harboring rock formations glittering with diamonds instead of quartz or other silicate minerals common on Earth. Imagine dark gray plains of graphite. Bubbling pools of tar. A smoggy methane atmosphere.

Scientists today report using the Spitzer Space Telescope to discover the carbon-rich recipe of a previously known exoplanet called WASP-12b. A press release today from Jet Propulsion Laboratory has more details:

Astronomers have discovered that a huge, searing-hot planet orbiting another star is loaded with an unusual amount of carbon. The planet, a gas giant named WASP-12b, is the first carbon-rich world ever observed. The discovery was made using NASA’s Spitzer Space Telescope, along with previously published ground-based observations.

Here at Goddard, exoplanet researcher Marc Kuchner received the news with barely concealed glee. In years past, his work contributed to establishing the hypothetical existence of carbon planets. The WASP-12b observations confirm it.

The implications are exotic. Weird things happen when the ratio of carbon to oxygen in a planetary system crosses the tipping point — that being a ratio greater than 1 to 1.

“When the relative amount of carbon gets that high, it’s as though you flip a switch, and everything changes,” Kuchner explains. “Everything would be different — like imagine, one day you’re a Yankees fan, the next day, Red Sox.”

WASP-12b is a gas giant, so its carbon-rich creations swirl within oceans of dense atmosphere. But what about terrestrial (i.e., rocky) carbon planets? Now it gets mighty interesting.

“If something like this had happened on Earth when it was formed,” Kuchner says, “your expensive engagement ring would be made of glass, which would be rare, because the atmosphere would be made of smog and the mountains would all be made of diamonds.”

artist concept of beta pic planetary system

Artist’s conception of the dust and gas disk surrounding the star Beta Pictoris. A giant planet may have already formed and terrestrial planets may be forming. The inset panels show two possible outcomes for mature terrestrial planets around Beta Pic. The top one is a water-rich planet similar to the Earth; the bottom one is a carbon-rich planet, with a smoggy, methane-rich atmosphere similar to that of Titan, a moon of Saturn. A team led by Aki Roberge of NASA’s Goddard Space Flight Center first presented the observation in the June 8, 2006, issue of Nature. Credit: NASA/FUSE/Lynette Cook


Kuchner says he thought initially carbon planets would probably be found in exotic stellar environs, like planetary systems whirling around pulsars or white dwarf stars. “But WASP 12 seems to be a pretty normal star, similar to the sun. If it could happen there, it could have happened here. And now that we know WASP-12b is a carbon planet. I bet we’ll start finding others.”

Well, that sounds familiar. In the early days of exoplanet discovery, we found “hot Jupiters,” gas giant planets orbiting shockingly close to their host stars. They seemed exotic until we started finding them all over the place. Now it’s “another day, another hot Jupiter.”

So perhaps carbon-rich planets won’t seem so strange someday, too. Case in point: a star called Beta Pictoris. Kuchner says Beta Pic is “mostly quite similar to the sun, but which has a planetary system and a disk around it that’s carbon rich. Not just a little carbon rich. It has nine times as much carbon as oxygen.  That’s even more carbon-rich than WASP-12b.”

We can only imagine what a planet might look like in such a carbon-mad place. We may never know, but it’s fun to wonder. The WASP-12b discovery gives us permission. “People sort of didn’t take the carbon planets idea seriously at first,” Kuchner says, “but this changes things.”


image of beta pic dust diskRIGHT:  This image of the circumstellar disk around Beta Pictoris shows (in false colors) the light reflected by dust around the young star at infrared wavelengths. The Beta Pic disk is very likely an infant solar system in the process of forming terrestrial planets. Credit: Jean-Luc Beuzit, et al. Grenoble Observatory, European Southern Observatory
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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.

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How big did you say that massive plasma snake…er, magnetic filament…on the sun was?

December 7, 2010 Leave a comment

My colleague Frank Reddy at Goddard Space Flight Center has kindly cooked up some quick illustrations to drive home the massive scale of that giant looping filament on the sun that everybody was oooing and ahhhing about in the blogpodcastotwittersphere yesterday, including the ever-blogolicious Bad Astronomer, Phil Plait. There’s a video of the beast out now, too.

To make these images, Frank laid Earth and Jupiter along the filament. In the full-disk illustration, Earth is a mere 15 pixels in diameter! By the way, the Earth image is the famous Apollo 17 photo, much shrunken, and the Jupiter snapshot is from Cassini.


sun_earth_jupiter_whole_600


sun_earth_jupiter_closeup_600


_____________________________________________________________________________________________________ OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA. //
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Cast Your Vote in the "Best of Goddard" FilmFest 2010

December 7, 2010 Leave a comment

“The envelope please!”

A hushed silence falls over NASA’s Goddard Space Flight Center — so quiet you can almost hear the voltage drop in a bismuth germanate gamma-ray detector array. So quiet that, even if you were in space, EVERYBODY WOULD BE ABLE TO HEAR YOU SCREAM!

“And the award for best NASA/Goddard science documentary of 2010 goes to . . . ”

Sorry, you’ll have to wait until next week to find out which lucky contestant takes the honor this year at the annual Best of Goddard Film Festival. Here at Goddard Space Flight Center, we’ll be filing into Building 3’s Goett Auditorium tomorrow (December 8th) for live screenings of the 12 films — and to cast our votes.

Don’t work for NASA? No problem! Click here to vote for your favorites. Online voting closes Wednesday, December 15, at noon.




























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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.

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Plasma mega-snake on the sun!

December 6, 2010 6 comments

close up image of solar filament

This just in from our “Solar Dynamics Observatory is blowing my mind” department — and SpaceWeather.com:  a plasma mega-snake on the sun.

A magnetic filament snaking around the sun’s southeast limb just keeps getting longer. The portion visible today stretches more than 700,000 km–a full solar radius. NASA’s Solar Dynamics Observatory took this picture during the early hours of Dec. 6th. The STEREO-B spacecraft, stationed over the sun’s eastern horizon, saw this filament coming last week. So far the massive structure has hovered quietly above the stellar surface, but now it is showing signs of instability. Long filaments like this one have been known to collapse with explosive results when they hit the stellar surface below. Stay tuned for action.



solar-snake-fulldisk_600
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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.

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The birth, life, and death of alien planets: Goddard exoplanet scientists give you an update on what we (think) we know

December 6, 2010 5 comments

exoplanet sun panorama

The official count of candidate planets around other stars recently hit a whopping 500. But when the first extrasolar planets — often called exoplanets — were discovered, many scientists weren’t sure if they should believe their own data. The first confirmed exoplanets were found around a stellar corpse called a pulsar, born of a supernova explosion of a star. And we also found lots of so-called hot Jupiters, huge steaming gasballs orbiting many times closer to their host stars than Mercury orbits the sun.

365 days of astronomy logoHow do exoplanets come to exist? How do they evolve over billions of years? And how do they die? If you’re curious and have 10 minutes, listen to my podcast, The Birth, Life, and Death of Alien Planets, on “365 Days of Astronomy.” (It’s a daily podcast produced by the International Year of Astronomy 2009.) You can also just download the (11 Mb) .mp3 file here and listen to it on your iPod or other media player. This blog post is adapted from the podcast transcript, if you prefer to read rather than listen to the 10-minute broadcast

The race is still on to discover more planets, and scores are promised thanks to missions like the Kepler space observatory. Meanwhile, down here on earth, exoplanets scientists are scratching their heads, mining their data, and tweaking their theoretical models to try and make sense of the diversity of alien worlds we have already found.

Here at NASA’s Goddard Space Flight Center, where I work as a science writer, we’ve got a whole group of scientists obsessed with exoplanets. They took me on a whirlwind tour of the birth, life, and death of planetary systems. It all starts with a collapsing cloud of gas that forms an infant stars surrounded by a spinning disk of gas and dust — the stuff of which planets are made. A protoplanetary disk.

JENNIFER WISEMAN: Young protostars are buried in a large envelope of dense gas, kind of flattened like a fluffy pancake, but it can extend out to thousands of astronomical units, the distance from the Sun to the Earth.”

DANIEL PENDICK: That’s Jennifer Wiseman. She studies star birth and is the new senior project scientist for the Hubble Space Telescope. She’s also the chief of Goddard’s ExoPlanets and Stellar Astrophysics Laboratory, which is home to many of the exoplanet researchers here at Goddard.

WISEMAN: You have this puffy but dense sort of pancake of gas, swirling around, and in the interior part of this, material is being gravitationally sucked into a tighter accretion disk that’s right around this young forming star.





PENDICK: OK, so far so good. We’ve got an accretion disk, which is where planets come from. What happens next? I asked Hannah Jang-Condell, a post-doctoral researcher at Goddard and the University of Maryland. She’s also a member of the Goddard Circumstellar Disks Group, about a dozen scientists here active in exoplanet research.

JANG-CONDELL: So basically you’ve got a star. It’s not burning hydrogen yet. You’ve got this disk of gas and dust surrounding it. And planets are starting to form in this disk.

PENDICK: Hold on — did she say dust? As in those fluffy dust bunnies that inhabit the underside of my couch? Not exactly. When astronomers say dust, they mean tiny bits of solid stuff, like minerals and ices, floating around in space. The dust grains are on the scale of a micron—a millionth of a meter—in diameter.

JANG-CONDELL: It’s assumed that as you build these things up from the micron size to the centimeter size, that things stay fluffy. So sort of loosely bound aggregates. So they are a lot like dust bunnies at that stage.

PENDICK: So much for interstellar dust bunnies. Now, back to the planet building stage of our story.






JANG-CONDELL: So there’s two main scenarios for the way planets form. There is the core accretion scenario. So you start out with dust particles and they collide and coagulate and become larger and larger bodies. When it gets about 10 to 20 times Earth’s mass it’s able to accrete gas, and then the gas will stay on it. From that point it can accrete gas and become a gas giant planet like Jupiter.

The alternative scenario is called gravitational instability. In that case, you have a massive disk, and it’s cool enough and dense enough for it to start self-gravitating. So in other words, the disk will fragment, it will start to form a clump, the clump will become self gravitating, and eventually it will collapse to form a giant planet.

PENDICK: This all takes place in the space of a few million years — a cosmic blink of an eye. Gas giants have to form before all the gas in the system has either accreted onto the star or is blown away by the star’s radiation.

Once the gas goes away, the infant planetary system evolves into something called a debris disk. As Goddard exoplanet researcher Aki Roberge explains, the planet-building process continues in debris disks, creating larger and larger bodies called planetesimals. In today’s solar system, planetesimals are known as asteroids and comets.

AKI ROBERGE: They start colliding and sticking. Roughly speaking, it’s just hit-stick-hit-stick, get bigger and bigger and bigger.

PENDICK: Sometimes the collisions are not so sticky. The planetesimals smash together and generate lots of smaller debris particles. In fact, huge dusty disks were discovered around other stars for the first time in the 1980s. Astronomers dubbed them ‘debris disks.’

ROBERGE: Over the years, there’s been lots of pieces of evidence collected that these debris disks, they really are young planetary systems. So they are like young, dense versions of our own Kuiper and asteroid belts, and our own solar system probably went through a phase very much like it, a debris phase, when it was young.

So any giant planets that would form in the system have already formed because there is no gas left to form any giant planets. And some planetary embryos, maybe Mars sized bodies, are there already. So what’s happening is the late stage of terrestrial planet formation. So you are building up from Mars to real Earths.

PENDICK: Terrestrial planets can have violent births, as embryonic planets up to the size of Mars slam into others and build up larger planets. Also at this time, water rich comets may stream in and collide with the young terrestrial planets. This provides the raw material for oceans and atmospheres.

Theory tells us these events must be happening in the dusty disks astronomers study. But we don’t see any of this directly.

ROBERGE: All you can really see, ironically enough, is the very smallest portion. So what you see is the dust, tiny, tiny little dust [grains.] This is the dust that’s produced when two asteroids crash together and break up, or the dust that’s in a comet’s coma that’s being expelled as they evaporate. So actually we see the indirect signs. We can see the tiniest material but we know it has to be coming from bigger things.

PENDICK: At some point, things do settle down a bit. But even in a mature planetary system, the action is far from over. Planets continue to migrate in their orbits, or even be ejected from the system in hair-raising close encounters. And if a planet orbits close enough to its star — even closer than Mercury orbits the sun — it could spiral inward and be consumed. In short, entire planets disappear from planetary systems. Goddard exoplanet researcher Brian Jackson explains.

BRIAN JACKSON: Once you get that close, tides raised on the host star and tides raised on the planet can affect the orbit of the planet. Because the rotation of the star is so much slower than the rate at which the planet is going around, the bulge tends to point a little bit behind the planet. And you can think about the gravitational interaction with that bulge always pointing behind the planet a little bit kind of yanks back on the planet and that can reduce the orbital distance between the host star and the planet.

Eventually its orbit will shrink enough that it will be destroyed. That can happen within a few billion years. So a lot of these close-in planets that we see aren’t going to last more than a few billion years.

PENDICK: And even planets farther out from the star can experience dramatic changes because of tidal forces.

JACKSON: If the planet’s orbit is non-circular, then what happens is the size of the tidal bulge when the planet is closest to its host star is bigger than when the planet is farther away. The shape of the planet will change as it goes around in its orbit. That change, that periodic flexing of the planet, dissipates energy inside of the planet. It can drive volcanism, which can cause outgassing and provide an atmosphere for the planet. And we see this sort of volcanism powered by tides in our own solar system, for example, Jupiter’s moon Io undergoes the same sort of tidal heating…and that drives the volcanoes that erupt on the surface of Io.

PENDICK: In fact, tidal flexing could hypothetically turn the surface of a rocky planet into a lava sea fuel massive supervolcanoes. Or it could cause just enough heating to maintain a warm and stable climate, as earthly plate tectonics does on our world.

We used to think that solar systems eventually settle down and become middle-aged and sedentary, with stable and predictable behavior. But this does not appear to be the case.

JACKSON: Among planetary systems, the rule seems to be that interactions can be very violent and dynamic and the orbits can evolve pretty dramatically over time.

PENDICK: Planetary systems can even come back from the dead after the most violent event nature has to offer — the supernova explosion of a star. Goddard post-doctoral scientist John Debes has studied these born-again planetary systems. In fact, the first planets ever discovered around other stars were found orbiting a pulsar — the superdense rotating remnant of a star that went supernova.

JOHN DEBES: What people think happened is that after the initial supernova explosion some of the material fell back into a disk, and that allowed these smaller planets to form. And the only reason we found them is because pulsars are amazingly precise clocks, and you could measure the timing of the pulses of the pulsar, and see that that would change due to the orbital wobble of these planets.

What’s great about that system, even though it’s the only one that’s been found, is it really shows the sort of basic process for forming a planet must be pretty easy to do, because if you can do it in the fallback disk of a supernova, you can do it just about anywhere if you have the right amount of material and the right conditions.

PENDICK: Hot Jupiters spiraling to their fiery doom… planets par boiled in molten lava… worlds born from the ashes of dying stars. It sure isn’t your grandfather’s solar system science anymore, with well-behaved old planets in their stately settled orbits. As telescopes give us even sharper views of alien worlds, it’s hard to predict what strange world await discovery.


Astronomer Carolyn Crow, also the center of the solar system.
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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.

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