The planets TESS finds will keep exoplanet scientists busy for years

One area that exoplanet scientists are becoming increasingly interested in is taking a deeper dive into the atmospheres of exoplanets. Doing so is difficult, as it requires picking out the tiny fraction of starlight that passes through these alien atmospheres when the planets transit their stars.

By comparing the chemical signature of a star when it has a planet in front of it to when it doesn’t, astronomers can work out what elements are in its atmosphere. This is easiest to do when the background star is bright. “The number of photons passing through the atmosphere is key to how much of a signal you can ultimately find,” says Sara Seager, deputy science director for TESS. “Planets that have a puffier atmosphere are better as well.”

To ensure that our own atmosphere doesn’t drown out the signal, this follow-up is usually done with space-based telescopes, be it with the new dedicated scopes such as ESA’s Cheops, or more general-purpose scopes such as Hubble and the upcoming JWST.

Such observations are difficult and can take a long time to both take and process, but over the coming decade we could soon find out what alien skies are like on planets around other stars.