# FIRST EXOPLANET IMAGE CONFIRMED!

Apr 30, 2005 6:58 AMNov 5, 2019 6:46 AM

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:

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?

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