Alien Atmosphere Hubbled

b-side.org writes "Yahoo! News has a story on yon giant hubble mirrorscope thingy locating an alien, mostly sodium, atmosphere. X10.com popunder ads also included free of charge." Mm....let's mix that atmosphere with water. T cuts in: This turns out to be the major discovery hinted at a few days ago.

Comments

A few things...

[joh3n]

1) The sodium bit: It's not that the planet's atmosphere is mostly sodium, it's just that sodium is rather easy to detect as compared to other elements (we use it to identify stars all the time). Also, given the spectral coverage of STIS (the spectrograph used to make the measurement), Na was probably the only strong line they could go for in one setting.

2) Why this is a big deal: Yes, we know there are gas giants elsewhere, but that's not the point. It's more of a proof of concept that we can measure the properties of an atmosphere of a planet outside the solar system. Plop a more sensitive instrument up there and you can go for smaller planets....and hopefully find signatures of methane and oxygen...boo-yah.

3) The unexpected bit (from the astronomers point of view) Hubble found it. Hubble's great and all, but spectra is not it's bread and butter. Most of us in the astro community were betting on Keck to find this first since a 10 meter on the ground with larger spectral coverage kicks the crap out of a 2.5 meter (Hubble)

Re:Sodium

[markmoss]

There's a better article in nytimes.com (registration required). The Hubble's spectrograph is detecting tiny traces of sodium in the planet's atmosphere as it transits between the star (its sun) and us. They set it to look for sodium, because that has the strongest spectrum lines of any element. The article didn't say, but I think these must be absorption lines where the starlight shines through the atmosphere of the planet, around the edges as it transits. I would assume it is ionic sodium -- you just plain don't find sodium in any other form.

The planet is Jupiter-sized, and close to it's sun, so the atmosphere is hot enough to melt copper. Not a good place to visit... But with the present methods for detecting extra-solar planets, any we can spot will be too big and too hot.

Mostly, planets are detected because their mass as they orbit makes the star jiggle just a little (the star and the planet orbit the common center of gravity -- which is still somewhere inside the star, but not the exact middle). The stars motion doppler shifts it's light, and so there is a periodic shift in the star's spectrogram. The bigger the planet is and the closer to the star, the more jiggle -- someone in another solar system looking at ours with instruments of similar capability wouldn't detect Earth because it's too small, and might miss Jupiter because it's orbit is too wide and slow.

This particular planet was detected by a different method; it happens that the planet's orbit causes it to transit between the star and Earth, blocking a small part of the star's light. If the planet is big enough, this drop in the star's intensity is detectable. But such an orbital alignment must be something like a one in a million shot...

Re:Drake Equation

[LMCBoy]

"the Drake equation gives us NO new information about the statistics of life"

This is true, but it's not the point of the Drake equation. Frank Drake came up with it back before he founded SETI, as a way to speculate quantitatively about the possibility of life elsewhere. It's utility is that it separates the unknown factors regarding life in our Galaxy, so that the mind can deal with each independently. I mean, think about it:

Conversation about life in the universe, pre-Drake equation:

"How many civilizations do you think there are in our Galaxy?"
"I have no idea."
"Heavy."
"Yeah."

Same conversation, armed with DE:

"How many civilizations do you think there are in our Galaxy?"
"Who knows? But there are billions of stars, and I think about half probably have a planetary system of some kind."
"Yeah, but how many of those could support life? Even in our system, apparently only 1 of 9."
"OK, so let's go with that, for now. But how many of the life-bearing planets would evolve intelligent life?...."

and so on. The Drake Equation provides a framework for speculation about The Big Question: Is there intelligent life elsewhere in the universe?. It was whimsically conceived, and it was not meant to provide new information about the question.