Blogs / Bad Astronomy

The very first image of a planet orbiting a star other than the Sun has been confirmed. They really did it; they bagged a planet!

I won’t keep you in suspense: here is the picture:

The planet is the red fuzzy blob to the lower left of the blue fuzzy blob. The blue blob is the parent star, and is a brown dwarf, a very low-mass star (it looks blue because this is a false-color image). The planet has about 5 times Jupiter’s mass, well within the range of being a planet and way too low to be even a brown dwarf, let alone a star. It orbits the star at about 1.5 times the distance Pluto orbits from the Sun. The two are close by as these things go: just 70 parsecs (230 light years) from here.

So how do we know that’s a planet? Ah, it’s a fine story to tell. Have a seat and get comfy; this’ll take a while.

We’ve known about other planets for some time now. The first were discovered in 1990, orbiting, of all things, a pulsar, a dead star. These are pretty interesting planets, given their circumstances, but they are not orbiting a sunlike star (though I highly recommend reading the story behind the discovery, it’s a grand tale, full of real science and real scientists).

The first planets orbiting stars like the Sun were found in 1995. They were not seen directly, but only through their influence on their parent star. A star, of course, has lots of gravity, so the planet orbits the star in a big circle (or ellipse). But the planet has gravity too, which tugs on the star. It’s like two people, one big and one small, locking hands and swinging around each other. The little one makes a big circle, and the big one makes a little circle.

As the star moves, this motion is betrayed through the Doppler shift, the same effect that makes a race car go “EEEEEEEEooooooowwwwwwwrrrrrrrrrrr” as it zips past you. When the star moves toward us in its tiny orbit around the planet (if you want to think of it that way), the Doppler shift means its light gets a wee bit bluer. When it moves away from us, the light gets a bit redder. This shift is incredibly small, and takes fantastically sensitive instruments to detect it. That technology only became available 10 years ago, and we’ve come pretty far: over 150 planets have been found this way.

While this is fantastic, it still leaves us semi-evolved apes dissatisfied: we want to see something! Those detections come about as plots of sine waves and wiggly lines.

I wanna see a planet!

Heehee. Now I can. This is so cool!

OK, I got distracted there. Back to the story.

There has been something of a race to get the first image of a planet around another star. I played a minor role in this race. When I worked on a camera onboard Hubble, we wondered if we could image a planet orbiting the nearest sunlike star, Alpha Centauri. I wrote some programs to simulate how the camera worked, and I determined that we might, might, just barely, detect one if the conditions were just so. But it would have been an extremely difficult observation, and we couldn’t convince the folks who controlled Hubble to do the observation– I really don’t blame them, given how monumentally hard this observation would have been , for so low a chance of success. We did search other, nearby stars, and never found one (duh, or else I wouldn’t be writing this blog entry now; I’d have written it years ago!).

Well, then came images from an infrared camera on Hubble. Looking for planets in the IR is good. Stars are bright, so bright that they totally drown out the feeble light from a planet. In visible light, that is. In the infrared, planets are much brighter, and stars dimmer. Instead of being a billion times brighter (as Alpha Cen was over any hypothetical planet I tried to simulate), in the IR stars might only be thousands of times brighter. That’s still a lot, but easier to deal with.

My friend Glenn Schneider had some intriguing data from the IR camera, showing a dim star (for the record, it was called TWA 6, because it’s part of a loose group of young stars called the TW Hydrae Association), with another, dimmer star next to it. The colors of the object were consistent with it being a planet. Had he found a planet orbiting another star? He couldn’t be sure, because it might be a background star masquerading as a planet. He needed proof.

The only way to know was to either wait a year to see if the two objects moved across the sky together (more on that in a moment, because it’s crucial to our tale), or to take a spectrum, break the light up into its colors like a rainbow. By doing that, you can tell the difference between a planet and a star.

So Glenn used the camera I worked on to take spectra, and asked me to help analyze the data. I spent months slaving over that data. Months! But the goal was sweet: to have proof of the first image of an alien world orbiting a far off star…

Other people (like my friend Eliot Malumuth) worked hard on the data too, but in the end we just couldn’t do it. The star’s light was swamping the fainter light from the other object. Dejected, we gave up. Turns out, later, follow-up observations showed it was a background star. Oh well.

How did we know it wasn’t a planet? Let’s back up a sec. The Milky Way Galaxy is a collection of hundreds of billions of stars (and clouds of dust and gas and other junk) in the shape of a flattened disk. The stars orbit the center, and that includes the Sun. Even at 200 km/sec, it takes about 240 million years to circle the Galaxy once. Yikes.

But other stars orbit at different speeds. So over years, we see the stars in the sky move with respect to each other. We call this their “proper motion” (I wrote a web page about this, with a Hubble picture showing this motion for a nearby star). So if you take an image of a star, wait some time, and take another one, you can detect this motion. See where this is going (har har)?

If we see a blip of light near a star, it might be a background star. So we wait a while, and then take another picture. If the nearby star moves a lot with respect to the other blip of light, chances are that blip is a star much farther away. If it were planet, it would share its stars motion across the sky.

With Glenn’s star, it turned out that the later observations showed the two objects not to be moving together. They were unassociated, and we didn’t have a planet.

Fast forward five years or so, to 2004…

Last year, a team led by astronomer Gael Chauvin used the prosaically-named Very Large Telescope in Chile, and they spotted something interesting. Near a faint red star called 2M1207 (ironically, in the TW Hydrae association!) was a fainter, even redder blip of light. Hmmm…they got a spectrum, and it sure looked like a young planet, still hot from its formation, but they couldn’t be positively, absolutely sure. The only way to confirm whether it was a planet or not was to wait, and get more images later. Then they could see if the two blips moved together.

Fast forward again, to April 2005…

Hey, that’s now!

Success!

The image above (clicking it takes you to a 220kb higher-res image) shows the proof. The blue line is the motion of the planet relative to the star if it’s not a planet, and the flat red line is if it really is a planet, moving with the star. Note the points on the plot– they are smack dab on the red line.

The two blips moved together. That means the last bit of doubt is gone. They did it! I now pronounce you star and planet. In fact, the star needs a name change: it’s now called 2M1207A. The planet is 2M1207b (stars are upper case, planets are lower case, so that’s not a typo).

My sincere and very exuberant congratulations to Gael Chauvin and his team who made this incredible image. Look at it! Sure, it’s young, only about 8 million years old (compared to 4.5 billion for the Earth), and it’s still so hot that water in its atmosphere is still steam. And sure, it’ll take a few million years to cool off, and even then it’ll be a gas giant probably much like Jupiter.

But it’s a planet. And you can see it.

As our technology gets better, we’ll find lower and lower mass planets. Then there may well be a quantum leap: NASA plans on building space telescopes which can image planets the size of Earth, normal, mature planets, just like Earth, if they’re out there.

I think they are, and I think we’ll see them. I wonder. My daughter is nine years old. By the time she’s in college, taking an astronomy class — will her professor show her an image of a world with blue oceans, green and brown continents, white clouds… orbiting Alpha Centauri?

NASA’s Deep Impact probe (yes, it was named well before the movie) is on its way to a very close encounter with Comet Tempel 1. It will pass by the comet this summer, taking close-up pictures, and will also release a chunk of copper that will smack into the comet (hence the name). This will excavate a pretty sizable crater, allowing scientists to peer inside a comet, and figure out what lies beneath. Well, really, what it’ll do is blast out junk from the comet, and the probe will then analyze the stuff ejected. But they do expect to get images of the crater, too.

Deep Impact is close enough now that it got its first image of the comet. Here it is:

That may not look like much, but the image was taken when DI was still 40 million miles from the comet! It’ll cover that distance in about 70 days, for a July 4th impact (scientists swear that’s a coincidental date).

When that chunk o’ copper hits the comet, it’ll dig a pretty big crater. How big? No one knows. So NASA decided to sponsor a contest: guess the size of the crater, and win a custom-made plaque from Ball Aerospace (the company that built DI). You can enter the contest here. One caveat: the answer must be in meters. They might have done it in Imperial units, but you know what they say: give someone 2.54 centimeters and they’ll take 1.609 kilometers!

I just heard yesterday that Philip Morrison died. Maybe you’ve never heard of him. But you’ve heard him.

He was a brilliant physicist. He played a major role in the Manhattan Project in WWII, and went on to do all sorts of great work, including pioneering the Search for Extraterrestrial Intelligence.

I knew his work two ways. One was through his great articles for Scientific American which I read as a kid (when I was much younger I used to wait for my dad to read the magazine, then I would grab it; I could hardly understand much of it, but I was laying the groundwork for my own life’s work). I just searched on Morrison’s name at the SciAm website and got 209 results!

But to me, and to a lot of people around my age, he will always be known as the hobbit-like voice narrating one of the best short documentaries of all time: Charles and Ray Eames’ Powers of Ten. You know the one: it starts with a guy snoozing on a picnic blanket, then zooms out, showing first Chicago, then Illinois, then the Earth, then the solar system, planet rushing by, the great void between stars, then stars, the galaxies, the Universe… then it zooms back in. When we get back to the sleeping man’s hand, we don’t stop there. We go in, zooming in more and more, past cells, chromosomes, DNA, carbon atoms, and finally passing through a proton made of quarks, vibrating madly.

All the while, Philip Morrison’s trademark voice was narrating this, telling us how far we’ve traveled, teaching us the powers of ten and scientific notation. It’s one of the greatest teaching tools of all time. It played on a loop at the Museum of Natural History in Washington, DC, and my class went there for field trips practically every school year when I was a kid. I must have seen the film dozens of times (given the topic, maybe I should say tens of times), listening to that weird voice going over the science of the journey. I would sit in the small darkened room, no bigger than an office worker’s cubicle, and stare in fascination. I loved the astronomy, of course, but there was something about zooming in, descending down into space until there was literally no matter to see, wondering what happened if you got yet even smaller… I was like a bird in front of a snake, fascinated despite the chill I felt.

That film was one thread in an tapestry of people and events that makes me who I am today: a scientist, a skeptic, a critical thinker. I never knew Philip Morrison, and that saddens me. But he was a part of my life despite that, and a part of a generation’s life. He showed us the whole Universe, from the impossibly large to the incredibly small, and for that I thank him.

Today, as I write this, it’s the 15th anniversary of the launch of the Hubble Space Telescope aboard the Space Shuttle Discovery (it was actually deployed from the Shuttle a day later; you can see a fun video of it here). If you haven’t seen them already, Hubble released two new images to celebrate: one of the Eagle Nebula, and the other of Whirlpool Galaxy.

The Eagle Nebula	M51, The Whirpool Galaxy

I was going to write a brief history of Hubble, but you know what? You can find that anywhere. So I’m gonna indulge myself (it’s my blog, after all) and talk a little about my own involvement.

In the spring of 1990, I was at the University of Virginia, and I had just finished my Masters degree. I was looking for a PhD project, and having no luck. Most faculty had no money, or no project (one had a fantastic project observing variable stars that was incredibly cool, but she had no funding at the time). I scoured all the relevant departments at UVa, but there was literally nothing I could find.

I had actually written and printed what amounted to a resignation letter from grad school, which I was prepared to hand to the department chair, Roger Chevalier. But when I told him my tale of woe, he said “Well, I do have this one thing coming up…” I asked him what it was, and he said it was observing supernovae (exploding stars) with Hubble. I was fascinated by supernovae, and Hubble was due to launch in a few months, and was the Great Hope of Astronomy at that time. So duh: I said YES.

I still have that resignation letter.

I started reading on the project: it was a massive program to observe supernovae, involving many hundreds of hours total of observing time and a dozen professional astronomers across the globe. I was very eager to get involved, get data, gets started!

I was in for a shock, when it was found that the telescope wouldn’t properly focus (shortly thereafter I got a little salt in the wound: the variable star project I turned down received wheelbarrows full of funding. Figures). But Hubble did return two images of a ring of gas surrounding the supernova SN1987A, and they were good enough for me to start working. In all honesty, I had very little idea of what I was doing; it was a (very severe) learning process. But over time I got a grasp of it, and as new images from Hubble came in, I eagerly incorporated them into my work. I won’t go into details here, but you can read about that here and here.

I defended my PhD in ‘94, and went on to eventually work on the Space Telescope Imaging Spectrograph, or STIS, a camera on Hubble. It took many grand and gorgeous images of astronomical objects, and I was privileged to work on many of them, processing and calibrating the images, and sometimes working on the scientific analysis (even publishing one project).

I left that project after nearly five years, to pursue a career in public outreach in California. I still miss the work sometimes, and got a jolt when STIS died on August 3, 2004.

But I still look back very fondly on all the fun, work, sweat, pain, torture and sheer joy of working on the world’s premier telescope. I have many other stories about Hubble, including some of the work I did, in the Bitesize Astronomy section of the main website. You may find some of them amusing (especially this one, a personal favorite).

On this, the 15th year of its pushing back the boundaries of our knowledge, let’s hope that it continues for years to come. The decision to de-orbit Hubble is not final, and Mike Griffin, the new head of NASA, has said he wants to look into a Shuttle mission to repair the ailing observatory (it has failing gyros, which stabilize its pointing, and two new cameras are sitting on the ground waiting to be installed).

I certainly hope it continues on, and provides not just the public with the thrill of its spectacular images, but also gives scientists, both young and old, a chance to expand our knowledge of the Universe. For me, that’s what this is all about.

I do a lot of writing, and it can be hard sometimes to capture the essence of how I feel about science. It’s such a grand adventure, full of learning, full of wonder, full of such amazing experiences. This is why it is so horribly upsetting to see people who clearly have no freaking clue about it, and would rather denigrate science from ignorance rather than once — just once, for a fleeting moment — take pause to understand what it is they so smugly reject.

It’s a madhouse! A MADHOUSE!

In another critical thinking blog, called Pharyngula, scientist P Z Myers has written a beautiful bit of prose describing this very situation. He has captured the soul of scientific study, if you will, and then shocks the reader with a contrasting account of arrogant cluelessness. The writer Myers is slamming has a political message, and I don’t want you to necessarily make any political surmising about me for linking to it. Willful ignorance, it so happens, has no political preference. And Myers is justified, hugely justified, in calling this guy to the carpet for such foolish opinions made in a vacuum. Read it and judge for yourself.

Last night, I was watching TV, and a dandruff shampoo commercial came on. The usual advertising slickness ensued, and then they had their tagline: “Our shampoo makes flakes go away”.

I really, really wish that were true. I can think of a lot of flakes I’d use it on.

OK, that title is a stretch. I’m going to New York to give a talk about Mars, but it’s not NYC, it’s actually Suffern, NY, to attend the Northeast Astronomy Forum (or NEAF) star party. I’m the keynote speaker, and I’ll be dissing claims of giant cities and faces on Mars. I love giving that talk. It’s fun — and gratifying — to show exactly where some anti-scientists are misleading the public. Plus, there are some old friends who will be at NEAF and it’ll be good to see them again. Also, I’ll be swinging by the Hudson River Museum planetarium in Yonkers, NY to give my general Bad Astronomy talk, too. You can find out times and locations by going to my calendar page.

Speaking of Mars, my old friend Jim Oberg, who is a space enthusiast and historian and sometimes NASA consultant, pointed out to me an interesting shot from Mars this morning. It’s a picture from the Opportunity rover, and it appears to have spotted a small crater (actually, two of them). The bigger crater is only 20 centimeters (8 inches) across, and the one in the background is a mere 11 cm (4.5 inches) across, making it the smallest ever seen on the surface of Mars!

Craters are formed when a meteor smacks into the ground (after that, it’s called a meteorite). Now, what most people don’t know is that smallish meteoroids (what we call the actual chunk of rock before it hits the round) actually don’t come screaming in like you see in science fiction movies. In reality, they slow way down while still high up in the atmosphere, and then fall freely after that. They might hit the ground at a hundred miles an hour or slower depending on the situation.

In this case, it really looks to me like something small (fist-sized?) hit the sandy surface of Mars at a pretty slow speed, making that sand pit you see in the picture (click on it to see the higher-resolution, full size image). The feature to the left of the bigger crater looks like the spray you’d expect from such an impact, blown a bit by the wind. The surface around the crater is clearly sandy, and sculpted by winds.

If this is true, it may be Mars’ youngest crater! And it may not be around for long; the winds will eradicate it soon too. Most interestingly, it may have a small meteorite at the bottom of it! It’s hard to know if these features are really young (like days old) or hundreds of years; the ages of features are very hard to determine. But that spray-like feature to the left of the bigger crater makes me think these guys are really young.

This situation is being discussed on the Bad Astronomy Bulletin Board. If you’re interested, join in!