An international team of scientists using the Gemini Observatory telescope in Chile has found a way to measure the amount of both water and carbon monoxide in the atmosphere of a planet in another solar system, roughly 340 light years away.
This is the first time scientists have been able to measure the actual amounts of molecules in the atmosphere of such a distant planet, and they hope the technique will be a significant leap forward in our understanding of planets in other solar systems—including how they form and where to look for signs of life.
“This opens up a whole new window into planetary atmospheres,” said study co-author Jacob Bean, an associate professor of astronomy and astrophysics at the University of Chicago. “Previously we could tell whether there were certain molecules, but not how many, and that makes a huge difference. It’s like being able to see the entire iceberg, not just what’s above water.”
Faint, faraway and fascinating
We now know there are thousands of planets outside of our own solar system, which are called exoplanets. But it took scientists so long to start seeing them because they’re incredibly far away and hard to see next to the blinding light of their stars. It’s only thanks to better telescopes and techniques in the past two decades that we’ve been able to find them at all, and the field is still evolving rapidly.
Because they’re so faint, scientists only have a few ways to tease out clues about what these planets actually look like. One of them is by looking for what molecules exist in these planets’ atmospheres. That can hint at what the planet’s surface probably looks like, how it formed, and even what might live there.
For example, alien astronomers would probably be able to find us by the amount of oxygen in our atmosphere, which you wouldn’t expect to see based on Earth’s geologic makeup—because it was put there by plants.
Previously, scientists could use instruments like the Hubble Space Telescope to get a preliminary sense of a planet’s atmosphere and whether or not it contains elements like oxygen or carbon. But they didn’t know how many atoms of those elements there were. “Knowing the abundance of an element—not just whether it’s present or not—makes a huge, huge difference in recreating scenarios of how a planet formed and what it looks like now,” said Bean.
So the team wanted to try to find out if they could use recent advances in processing techniques to pick out the abundances of the primary molecules that are made up of carbon and oxygen atoms.
They focused on a planet known as “WASP-77Ab,” a type of exoplanet called a “hot Jupiter” because they are like our solar system’s Jupiter, but roughly 20 times hotter.