Imagine an infantile version of our 4.6 billion-year-old sun. Now picture a “failed star,” a brown dwarf, about the size of Jupiter, tightly orbiting that 12 million year old stellar baby–at the distance Uranus orbits our sun. Astronomers have just found such a duo: a star about the mass of our sun with an unusually close brown dwarf companion.

Of the similarly situated brown dwarfs that astronomers have imaged, most keep their distance, orbiting at about 50 AU (or 50 times the average distance from the Earth to the sun). A team of astronomers believe the distance between this young sun, called PZ Tel A, and its dwarf companion, PZ Tel B, is less than half that, a mere 18 AU.

A paper to appear in Astrophysical Journal Letters details the find, which was made using images from the Near-Infrared Coronagraphic Imager, on the Gemini-South telescope in Chile. The researchers predicted the orbit by using two observations, one in April of 2009 and another in May of 2010 and then calculated the brown dwarf’s motion using a computer model.

Because PZ Tel A is young and sun-like, researchers say, that it might present a good history lesson on our own solar system.

In fact, PZ Tel is young enough to still possess significant amounts of cold circumstellar dust, which may have been sculpted by the gravitational interaction with the young brown dwarf companion. This is the material that can form planets so the PZ Tel system is an important laboratory for studying the early stages of planetary system formation. [Gemini Observatory]

Astronomers say that the brown dwarf is about Jupiter’s size, but is around 36 times its mass. Though they have imaged PZ Tel A before, they couldn’t pick out its dim companion because of its proximity.

An older image, taken seven years ago and reanalyzed by Laird Close, a professor at UA’s Steward Observatory and the department of astronomy, showed PZ Tel B was obscured by the glare from its parent star as recently as 2003, indicating its orbit is more elliptical than circular.”Because PZ Tel A is a rare star being both close and very young, it had been imaged several times in the past,” said Close. “So we were quite surprised to see a new companion around what was thought to be a single star.” [University of Arizona]

The Near-Infrared Coronagraphic Imager gave them more power than previously possible, as its a high-contrast instrument designed for finding dim bodies circling bring stars, like exoplanets or brown dwarfs, and can pick out a companion up to one million times fainter than the host star.

The research team was able to take pictures so close to the star by using an adaptive optics system and coronagraph [a device to block out light from the brighter star] to block our excess starlight. They then applied specialized analysis techniques to the images to detect PZ Tel B and measure its orbital motion. . . “We are just beginning to glean the many configurations of solar systems around stars like the sun,” said Michael Liu, NICI campaign leader. “The unique capabilities of NICI provide us with a powerful tool for studying their constituents using direct imaging.” [Space.com]

An international team is now using the telescope to complete a 300-star survey, the largest such survey to date, so hopefully more brown dwarfs will come out of hiding soon.

Related content:
80beats: A Hidden Cosmic Neighbor: Cool Brown Dwarf Found Lurking Near Our Solar System
DISCOVER: Hi Ho, Hi Ho—Brown dwarfs are the missing links between stars and planets
DISCOVER: Works in Progress—When it’s a planet that’s not a planet
Bad Astronomy: Brown Dwarf T Party
Bad Astronomy: The Upper Limit to a Planet

Images: Jon Lomberg, provided by Gemini Observatory, and Beth Biller and the Gemini NICI Planet-Finding Campaign

I have a Martian mystery for you today, and one that is writ quite large and dramatically. It seems weird at first, then simple next, but when you dig deeper — literally — things get very weird indeed.

It all starts with an out-of-control awesome picture that honestly made me reel back and say "Wow!"

I present to you out-of-control awesome:

Wow!

Click the pic to embiggen. This unnamed crater is about 700 meters (roughly half a mile) across, and sits in the northern mid-latitudes region of Mars. It’s interesting, isn’t it? The multiple concentric bowls of the crater are trying to tell us something, but what?

My first thought, also mentioned on the HiRISE blog, is that this is a coincidental double impact: the big terraced crater was the original impact, then a later, second object impacted almost exactly in the center of the older one, hitting the bulls-eye like William Tell splitting an arrow.

The topography seems to support that; the inner crater has a raised rim, as you might expect from a second impact, and that would be hard to explain in a single impact. The terracing — shelf-like structures sortof like an upside-down wedding cake layering — is seen sometimes when an impactor smacks into layered ground. Imagine a layer of dirt on top of ice on top of rocks: each layer reacts differently to the impact, leaving the circular, concentric shelves in the crater bowl.

Note too that the central crater doesn’t look exactly centered, supporting a second impact.

Case closed… but wait, Your Honor! We have a surprise witness!

This picture is actually part of a much larger region which provides some context:

You can see the extensive ejecta blanket (excavated material laid down from the impact ) around the crater now, which is nifty. But note the smaller crater to the lower right (indicated by the arrow): it looks a lot like the bigger crater! There’s a shallow bowl with a deeper crater almost but not quite in the center. There’s no terracing, but it’s a smaller impact and wouldn’t have dug so deeply into the surface.

So what gives? If all we had here was the big crater, I might believe the coincidence of a nearly perfect second impact bullseye inside it. But two of them? Right next to each other?

It seems unlikely, to say the least. And I thought I had an explanation for it… which I’ll give you. But note: I chatted for a few minutes with Alfred McEwen, the Principle Investigator of the HiRISE camera (which took the image), and he told me things still aren’t quite as they seem. Keep that in mind while I describe my thought…

My idea is/was this: both of those craters were single impact events. The terrain itself must explain the weird structures; there must be several layers of material with different solidity. In the lower right crater, the softer surface material deformed and splashed back, forming a shallow bowl. Underneath it is a stronger material, forming the raised rim central crater that’s slightly off-center. The fact that’s it’s not centered may be due to sloping in the surface, or that the surface layer isn’t constant in thickness across the surface. Perhaps there is stronger material to the left which resisted the impact pressure, leaving the inner crater off-center once the event was over.

This explains the big crater too. The outer bowl is shallow. Inside that is a raised rim, as you’d expect from a stronger material. The impactor was big enough to dig below even that layer to a third, deeper and even more resilient layer, leaving a beautiful raised rim. It’s not centered either, again perhaps due to the layers being irregular in thickness or to different material strengths in the layers themselves.

Finally, in the context image, you can see lots of shallow smaller craters. Again, I think this shows the top layer is something soft like ice, which leaves those barely visible bowls behind after smaller impacts.

Tadaa! Done.

But wait! Not so done. As Alfred pointed out to me, note that the second crater is actually sitting on the ejecta blanket from the first one (which is how we know that the smaller crater impact occurred after the bigger one). Since it’s on top of that material, the ground underneath the impact would’ve been different than the ground into which the original impactor hit. The other shallow craters are all sitting in that material as well. So we can’t simply state that the terrain was similar to the original event because the original impact changed the surface structure.

Also, the detail of the structure is difficult to interpret. Turns out that at this latitude glaciation is common, and that tends to screw up details, changing the way things look. Interestingly, the rim of the innermost crater in the big crater looks pretty fresh, too, like it happened after the original event, supporting the William Tell idea that a second asteroid impact hit right in the middle of the previously excavated crater.

Finally, in the top image, look at the floor just outside that innermost crater. See the two crescent-shaped lobes at 1 and 2 o’clock? Those may be slumped material from the walls of the crater. If a second impact happened in the center of a pre-existing crater, you’d get some disturbance of the material, including debris flowing down from the walls.

So what do we conclude?

This place is a mess. That’s what I conclude. Alfred said my idea that layered terrain explains most everything has some merit, but so does the idea that a second impactor did the deed. We simply can’t tell.

If you think I’m having fun figuring this out, then dingdingding! I am. Because it is fun. This is good old-fashioned sleuthing, detective work on the scale of a city block. When we look at pictures like these we get evidence of a crime scene, perhaps millions of years old — talk about a cold case! — but still fresh enough that we can puzzle out what happened. The big crater is the main clue, drawing our attention, but the second, smaller crater may be a smoking gun, the surprise evidence that just might make everything else make sense.

It’s CSI Mars. But in this case it’s not some procedural drama on TV. It’s real, it’s huge, and it’s sitting there on another world for everyone to see. All you need to do is go there and look.

I know I haven’t been posting much astronomy the past few days — Comic Con, w00tstock, and "Bad Universe" have kept me hopping — so to make up for it a little bit, here’s a lovely image sent back a billion kilometers from Cassini:

This is Tethys, an ice moon of Saturn. The angle of Cassini, Tethys, and the Sun light the moon as a crescent. The most obvious feature is Ithaca Chasma, a (more than) thousand-kilometer-long gash in the side of the object. Note that Tethys is only about 1000 km in diameter, so the chasm runs along a third of the moon’s surface (circumference = diameter x π, remember).

How big is that? Stand up and take a long stride. That’s about one meter. Now do it 999,999 more times. That’s a megameter: a million meters, or 1000 kilometers. Better pack a lunch.

The chasm is billions of years old, and may have formed when water inside the moon froze, expanded, and cracked the surface open. It’s a hundred kilometers across and 3-5 km deep, too. It’s far larger than the Grand Canyon, the largest canyon on Earth.

Space is big, and weird, where even small objects have huge features. It’s surprising, but surprising things are the best things to know.

Tip o’ the dew shield to Carolyn Porco.

They went to investigate solar wind-stirred storms in our planet’s magnetic field, but, after working for three years, two NASA solar-powered probes faced a dark demise, trapped in the Earth’s shadow. NASA researchers now think they can give the twin satellites another shot by altering their courses and sending them instead to study the moon.

NASA launched the probes in 2007 as a set of five identical satellites in the THEMIS Mission (Time History of Events and Macroscale Interactions during Substorms), meant to orbit Earth and send information during brief (2-3 hour) “substorms” when the magnetic field surrounding the Earth releases stored energy from solar winds. To understand the start of these “space tornadoes” responsible for the northern and southern lights, NASA placed the probes in very precise orbits, but for two craft that meant, one day, they would face prolonged battery-draining time in the Earth’s shadow.

“When we realized that the satellites would be going into very deep shadows, we started thinking of different methods for saving them–even before they were launched,” lead scientist Vassilis Angelopoulos, at the University of California, Berkeley, told Discovery News. “We realized that if we had enough fuel to change their orbits, the moon’s gravity would start pulling them up.”[Discovery News]

As Discovery News reports, funding is still pending for the new mission called ARTEMIS (Acceleration Reconnection and Turbulence and Electrodynamics of the Moon’s Interaction with the Sun), but the two satellites are already moonward bound. By firing their thrusters to extend their orbits, scientists started moving them closer to the moon in September of 2009, New Scientist reports. If the mission gets final approval, the recycled probes will move into position 62 miles in front of and behind the moon (relative to the Sun), and will give researchers a look at how the moon’s magnetic fields interact with solar winds.

The gravitational slingshot effect from these lunar encounters, as well as the probes’ close passes near Earth, changed their trajectories drastically – you can see the technical details [and artist renderings] here (pdf). Their own thrusters should be able to do the rest of the job, putting them in orbit around the moon in 2011. . . Not bad for two spacecraft that would have been space junk by now without this creative rescue plan.[New Scientist]

Related content:
80beats: “Space Tornadoes” Power the Northern Lights
80beats: Distant Turbulence in the Magnetic Field Triggers the Northern Lights
DISCOVER: Seeing the Light takes readers to an aurora research station in the Alaskan interior
DISCOVER: Space Weather explains the damage that solar storms can wreak

Image: Artist’s concept of original THEMIS in orbit. / NASA

Beware death from above! So blared science headlines yesterday. Citing a study in the Journal Icarus that said a huge asteroid perhaps could have a 1 in 1,000 shot of striking earth late in the next century, stories broke such as,

“Will a Giant Asteroid Kill Us All in 2182?”

“Asteroid Could Destroy Human Life on Earth by 2200”

“Huge asteroid on possible collision course with Earth (172 years from now)”

“Mark your calendars: Potentially hazardous asteroid might collide with Earth in 2182”

They’re correct in that there’s a giant asteroid out there called 1999 RQ36, and there’s a small chance it might hit us in a just less than couple hundred years. There’s just one problem: It isn’t news, though you wouldn’t have gotten that from the articles. The study everyone is referring to came out last year—it was in Icarus last October.

Confused why there was a press release yesterday that blew up into this wave of coverage, I emailed study coauthor Maria Eugenia Sansaturio of the Universidad de Valladolid in Spain to see if there was anything new to report about the asteroid. Her reply:

The answer to your question is that there is nothing new. I’m still trying to understand how this has made it to the international media. I was contacted by the Spanish Foundation for Science and Technology because they wanted to prepare a report on it and inform the Spanish Media, even though the article had been published in 2009…. and here I am overwhelmed with mails and phone calls from all over the world!

So the risk from 1999 RQ36 isn’t exactly new (and the press release in English caught Sansaturio by surprise, to say the least). Apparently, she says, the study just now got on the SFST radar, and that organization’s release set science publications humming about killer asteroids.

But, whether this asteroid’s path is old news or not, we shouldn’t dawdle in thinking about how we might avoid it or asteroids like it. In this case, we’ve only got 172 years—and we already wasted one year getting the news out.

172 years into the future is a long time, and humans aren’t exactly well-known for preparing for future events over those kinds of time scales. But time is one thing we’ll need if we are to protect future generations from a potentially catastrophic impact event [Discovery News].

Of course, the last time there was a giant hubbub over an asteroid that might kill us all (we’re looking at you, Apophis), subsequently improved data all but ruled out a disaster. So don’t panic; grab a telescope.

Related Content:
DISCOVER: What To Do Before the Asteroid Strikes
80beats: Asteroid Photo Session: Rosetta Spacecraft Snaps Pics of Battered Lutetia
80beats: Danger, President Obama! Visiting an Asteroid Is Exciting, But Difficult

Image: ESA, NASA, JAXA, RAS, JHUAPL, UMD, OSIRIS (asteroids visited by spacecraft, created by Emily Lakdawalla)

I never get tired of the stunning pictures being sent to Earth from the Lunar Reconnaissance Orbiter. This one is particularly cool:

It’s a little weird, isn’t it? What you’re seeing is sunset over some mountains on the Moon, with only the peaks popping up into the sunlight. It might help to pull back a bit:

[Click to embiggen.]

That’s a little better. You can see the long shadows of the two mountains on the hills farther back, giving the image a bit of context and relief.

But you’re still missing the coolest part. Ready? Here’s the entire shot:

Whoa! Getting the picture now? Those three mountains are actually the central peaks of the crater Bhabha, a 64 kilometer (40 mile) wide impact scar on the far side of the Moon. With really big impacts, the shock waves bounce around inside the crater bowl, making the rock flow like a fluid. The rock flows outward, then sloshes back inward, splashing up to form peaks. Usually there’s only one, but Bhaba has three.

This shot is from the west, facing east. It was taken just minutes before the Sun set over the peaks, throwing them into two weeks of darkness — remember, the far side of the Moon gets light just like the near side; when we see a thin crescent Moon that means the Sun is shining down on the other side, just like day on one side of the Earth means night on the other.

This picture is a vivid reminder that the Moon is a world in its own right. Eventually, I hope, people will once again get to see views like this by simply looking out the window. Until that time, LRO will provide us with these amazing pictures.

Image credit: NASA/GSFC/Arizona State University

I just found out that video of my talk at w00tstock has been posted on YouTube. The quality is a little shaky, since it was a handheld video taken from a distance back, so some of the pictures may be hard to discern, but I think it suffices to get the point across.

This may surprise you, but the content is pretty much Not Safe For Work. Yeah, I know: I’m not generally known for that. But hey– it’s an astronomy talk! What better place to go a little blue?

The video is in two parts; the first has the last couple of minutes of the warmup before my talk (I came on after the intermission), and the second part includes the premier of the trailer for my new TV show. The reaction of the audience was… well. It made me happy indeed.

Here are both parts. Part 1…

… and Part 2:

That last slide with the Hubble image says, "W00tstock: Where no astronomer has gone before."

I want to make sure I give plenty of credit Amanda Bauer, aka AstroPixie, once again for her inspiration for this talk. It’s something I’d been thinking of doing for a long time, but her blog post really got things started. Way-hey. Giggity.

There are pictures going up about w00tstock all over the place, so check with Flickr to see ‘em. And also, please read Wil Wheaton’s thoughtful and wonderful words about that night.

Thanks also to Kevin Savino Riker for posting that video. One of the beautiful things about w00tstock is that everything is licensed under the Creative Commons theme, which means it can posted publicly. Why? Because like Wil, Adam, Paul & and Storm, I agree that things like this get better the more they are shared, and become more valuable when they cost less. Or nothing at all.

[Brief update: Julia Sherred has many more w00tstock videos on her blog.]

Lake Ontario has some key differences compared to her equally-sized sister lake, Ontario Lacus: The Great Lake has water; Ontario Lacus has methane, ethane, and propane. The Great Lake invites sunbathers; Lacus’ beaches, almost ten times further from the sun, are icy cold. The Great Lake is located on Earth; Lacus on Saturn’s largest moon, Titan. Despite all these distinctions, new research points to an important similarity: liquid levels in both lakes change with the seasons.

From June 2005 to July 2009, the Ontario Lacus shoreline has receded by about 6 miles, Alexander G. Hayes and his coauthors report in two papers submitted to Icarus and the Journal of Geophysical Research. Looking at other lakes in Titan’s southern hemisphere, it seems they are dropping in depth by about three feet per year.

Despite its shoreline’s rapid retreat, there is little worry that Ontario Lacus and other Titan lakes will disappear forever. Scientists expect that the evaporation is just part of a cycle of evaporation and condensation, that changes with the seasons. The four years of observation, carried out by NASA’s Cassini spacecraft, represents only the period from about mid-summer to fall, since a Titan year lasts 29.5 Earth years.

The discovery that Titan’s lakes are evaporating. . . suggests that there are active weather and geological cycles on Titan analogous to those on Earth. But on Titan the liquid driving those cycles is not water but methane, explained Oded Aharonson, a planetary scientist at the California Institute of Technology.“This is a wonderful opportunity and rare in the solar system to observe a planet with working liquid on its surface, a volatile agent that is responsible for altering its geology and participating in its weather cycle by evaporating and precipitating,” Dr. Aharonson said.[New York Times]

The Synthetic Aperture Radar (SAR) on the Cassinni spacecraft provided the data to help the researchers determine the lakes’ properties and see into their depths. Hayes explains:

“[The liquid] is fairly clear to radar energy—that is, transparent, like liquid natural gas.” Because of this, radar can see through the liquid in Titan’s lakes to a depth of several meters. “Then the radar hits the floor, and bounces back,” he says. “Or, if the lake is deeper than a few meters, the radar is completely absorbed, producing a ‘black’ signature.”[California Institute of Technology]

By watching how images created from this radar data (see image right) changed over four years, the researchers witnessed the evaporation in detail.

“Cassini continues to take our breath away as it fills in the details on the surfaces of these far-off moons,” said Linda Spilker, Cassini project scientist based at JPL.[NASA/JPL]

Given all that evaporated methane, a visit to the surface might have a similar effect.

The amount of methane gas produced by the changes seen so far exceeds the methane expelled by all the cows on Earth over a year, according to the press release. Yeah, might want to rethink that vacation after all. [DiscoveryNews]

Related content:
80beats: Weird Chemistry on Titan *Could* Be a Sign of Methane-Based Life
80beats: New Take on Titan Hints at More Fuel for Potential Life
80beats: New Evidence for Ice-Spewing Volcanoes on Saturn’s Moon Titan
80beats: Hydrocarbon Lake on Saturnian Moon May Be a Hotspot for Alien Life
80beats: On Saturn’s Moon Titan, It’s Raining Methane

Image: NASA & Cassini Radar Science Team, NASA/JPL/Caltech

Graphing variables is a critical skill in science. If something depends on something else — like the speed of sounds depends on air density, or the surface gravity of an object depends on its size — then if you plot the two things on a graph, you should see a pattern. The result is a line, or a curve. If the two things don’t depend on each other, you get a random collection of dots: a scatter plot.

About a hundred years ago, two astronomers plotted the brightness of stars against their color (from blue to red) and what they found was amazing: a clear connection between the two! In fact, stars fell into several groups, and over the years we’ve learned about why that happens. Most stars are stable, like the Sun, and fall into the Main Sequence of the plot. Some are old, some young, some dying, some dead. And they all have their place in what we now call the Hertzsprung-Russel diagram, or H-R diagram for short. It’s one of the most useful tools astronomers have ever created.

And now my friend Stuart who runs Astronomy Blog has done it one better: he’s created an H-R diagram of media stars. It’s awesome:

That’s really funny, and I wish I had thought of it. The vertical axis is fame, as denoted by Google results, and the horizontal axis is peer-reviewed papers. I’m actually only first author on I think two papers, but I was listed as author on a lot due to my work on Hubble. So I do OK on this diagram. I note that Brian Cox is more luminous than me, but then, he’s an actual rock star. If there were a branch for white main sequence stars, he and I would be in a dead heat.

Next up, I hope: a space-time diagram showing warping due to massive astronomers.

[I know I already posted this, but the video of the trailer had to be taken down, fixed, and put back up, so I'm reposting to give everyone a chance to actually watch it. Everything works now. Yay! Also, it's up on reddit (actually twice) and Fark, too.]

Finally, at last, after many months, I can now officially reveal the Sooper Sekrit Project that has kept me so busy over all this time. I think you’re gonna like this… so why not just jump right in to the teaser trailer posted online by a small TV network you may have heard of called THE DISCOVERY CHANNEL!

[evil laugh]

How ’bout that?

I’ve been working with the Discovery Channel on hosting a new TV science show called "Phil Plait’s Bad Universe". It’s a three-part program where I dissect issues in astronomy and science, putting claims to the test. There’s no air date yet, but I’m hoping it’ll be on your TV sets this fall.

As you can see in the trailer, the first episode is about asteroid impacts, and we tackle the issue in a way that I don’t think has been done on TV. I get right into the mix, blowing things up, flying in a jet, going where the action is so that I can participate in experiments with scientists and try to find out what works and what doesn’t. The idea here is not to have some dry, narrated documentary. Instead I will show you what’s going on, take you along, so that you can see how these things work and what we’re doing to investigate these issues.

I’ve been having a tremendous time filming this, flying around the country, seeing things I ordinarily would never get to see. And the beauty is, you can come too!

Eventually I’ll post some pictures I’ve taken on this adventure, and we’ll be posting more video online as well as more information about the show soon. I’d like to thank everyone at Discovery Channel and Morningstar Entertainment for giving me this chance to fulfill a long-standing dream of mine. We’ve worked very hard on this program, and I hope you like it.

Yay!