Alien atmospheres

Washington Post unveils our first observations of the atmosphere on an Earth-like planet outside the solar system:

For the first time ever, scientists are sniffing out the secrets of a “super-Earth” — the type of planet thought to be the most common in our galaxy. In a study published Tuesday in the Astrophysical Journal, a team led by scientists from University College London report on the atmosphere of exoplanet 55 Cancri e, also known as Janssen.

Now, thanks to data from the Hubble, scientists have confirmed that this rocky hell-scape lacks water. They detected signs of hydrogen and helium in the atmosphere but no water vapor to speak of. Hints of hydrogen cyanide could indicate a carbon-rich atmosphere, according to the scientists. That would make sense, since Janssen’s mass and radius led scientists to believe it might be carbon-rich — earning it the nickname of “diamond planet.”

Scientists can determine the makeup of a planet’s atmosphere by watching as it transits in front of its host star. The way the passing planet changes the light of the star behind it — light that’s passing through the planetary atmosphere on its way to our line of sight — can reveal what molecules are clinging to it.