Hubble smelt who dealt it

Bad Astronomy
The entire universe in blog form
March 19 2008 2:30 PM

Hubble smelt who dealt it

Scientists have used Hubble to detect methane in the atmosphere of a planet orbiting another star for the first time and to confirm the existence of water vapor there as well.

This is not an easy thing to do! The planet is so close to its star that they can't be separated in an image, and the star totally overwhelms the light from the planet. However, when the planet is between the star and us (think of it as a tiny and very distant eclipse) the starlight passes through the planet's atmosphere, which absorbs some of the light. Methane is very good at sucking down infrared light in fact, so when you look in the infrared you see the star looking a bit dimmer.

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  


If you take a spectrum -- break the light up into individual colors -- you can get pretty detailed information about the starlight. In this case, the absorption by methane in the planet's atmosphere is pretty clear.

A spectrum is like a fingerprint: it identifies the element or molecule, how much of it there is, and even in some cases its temperature. The spectrum obtained using Hubble indicates the presence of methane and water vapor.

This is an important first step in understanding exoplanetary atmospheres, especially since we don't know all that much about these giant Jupiters that orbit close in to their parent stars. In this case, the planet, called HD 189733b, is about 63 light years away, and orbits its star in just about two days. We don't expect there to be life on it -- the tops of the clouds are at about 1700 degrees Fahrenheit -- but just finding these two molecules means they must be abundant in other planetary systems.

Now here's a dash of some slightly chillier water on these findings. First, they aren't surprising: I'd be far more surprised if we didn't find these molecules in the planet's atmosphere. We've seen plenty of both water and methane in space; in fact I worked on spectra of a brown dwarf that showed water vapor (literally steam in this case) in its atmosphere -- plus, the water vapor was previously detected using Spitzer (the telescope, not the governor). Methane is a very simple molecule, and should form anywhere there is carbon, hydrogen, and low enough temperatures so that the molecule doesn't break apart.

To me, the import of these findings is that with equipment we already have, we can probe the atmosphere of a planet over 600 trillion kilometers away. That's cool. That implies very strongly that with the next generation of space and ground-based telescopes being built now, we'll soon have an even better glimpse into the air out there.

And yes, I know that methane is not what makes, um, human emissions smell bad, but I couldn't resist the title.


The World

The Budget Disaster that Sabotaged the WHO’s Response to Ebola

Are the Attacks in Canada a Sign of ISIS on the Rise in the West?

PowerPoint Is the Worst, and Now It’s the Latest Way to Hack Into Your Computer

Is It Offensive When Kids Use Bad Words for Good Causes?

Fascinating Maps Based on Reddit, Craigslist, and OkCupid Data


The Real Secret of Serial

What reporter Sarah Koenig actually believes.


The Actual World

“Mount Thoreau” and the naming of things in the wilderness.

In Praise of 13th Grade: Why a Fifth Year of High School Is a Great Idea

Can Democratic Sen. Mary Landrieu Pull Off One More Louisiana Miracle?

  News & Politics
Oct. 23 2014 3:55 PM Panda Sluggers Democrats are in trouble. Time to bash China.
Business Insider
Oct. 23 2014 2:36 PM Take a Rare Peek Inside the Massive Data Centers That Power Google
Atlas Obscura
Oct. 23 2014 1:34 PM Leave Me Be Beneath a Tree: Trunyan Cemetery in Bali
  Double X
The XX Factor
Oct. 23 2014 11:33 AM Watch Little Princesses Curse for the Feminist Cause
  Slate Plus
Oct. 23 2014 11:28 AM Slate’s Working Podcast: Episode 2 Transcript Read what David Plotz asked Dr. Meri Kolbrener about her workday.
Brow Beat
Oct. 23 2014 4:03 PM You’re Doing It Wrong: Puttanesca Sauce
Oct. 23 2014 11:45 AM The United States of Reddit  How social media is redrawing our borders. 
  Health & Science
Bad Astronomy
Oct. 23 2014 7:30 AM Our Solar System and Galaxy … Seen by an Astronaut
Sports Nut
Oct. 20 2014 5:09 PM Keepaway, on Three. Ready—Break! On his record-breaking touchdown pass, Peyton Manning couldn’t even leave the celebration to chance.