NASA's TESS Finds Buzzing Cosmic Neighborhood With Two Super-Earths

No, there probably aren't any aliens over there. But these exoplanets could help us figure out where aliens might be.

Monisha Ravisetti Former Science Writer
Monisha Ravisetti was a science writer at CNET. She covered climate change, space rockets, mathematical puzzles, dinosaur bones, black holes, supernovas, and sometimes, the drama of philosophical thought experiments. Previously, she was a science reporter with a startup publication called The Academic Times, and before that, was an immunology researcher at Weill Cornell Medical Center in New York. She graduated from New York University in 2018 with a B.A. in philosophy, physics and chemistry. When she's not at her desk, she's trying (and failing) to raise her online chess rating. Her favorite movies are Dunkirk and Marcel the Shell with Shoes On.
Monisha Ravisetti
4 min read
A depiction of NASA's TESS satellite exploring the universe.

An illustration of NASA's TESS satellite between two exoplanet worlds.

MIT News, with TESS Satellite figure courtesy of NASA

Here's your friendly reminder that our solar system is but a molecule of water in the universe's ocean.  

NASA's Transiting Exoplanet Satellite Survey, better known as TESS, has spotted a buzzing galactic neighborhood only 33 light-years away from our planet. It has a central star, a couple of planets circling that star, and according to the scientists behind this alternate reality discovery, there are at least two terrestrial, Earth-size worlds in the pack.

If you could travel at a tenth the speed of light, it would take you something like 330 years to get to this solar system-like place in the galaxy. Obviously, though, that isn't possible, for several reasons.

But by using special Earth-borne equipment like telescopes and space-borne spectrometers -- maybe even the James Webb Space Telescope once it's booted up and online -- we can paint a pretty clear picture of what this neighborhood looks like. 

With that in mind, the researchers are presenting comprehensive details about this multiplanet system on Wednesday at the meeting of the American Astronomical Society in Pasadena, California, so the astronomy world can shortlist these new exoplanets for important exoplanet studies. 

And they've already provided a sneak peek into their findings, in a press release from the Massachusetts Institute of Technology. 

What we know so far is that the system's host star is dubbed HD 260655 and is relatively small, cool and categorized as an M-dwarf. M-dwarves are significantly less massive than our sun, a G-type main sequence star, yet are 10 times as numerous throughout the universe.


This test image from one of the four cameras aboard the Transiting Exoplanet Survey Satellite (TESS) captures a swath of the southern sky along the plane of our galaxy. 


The inner planet orbits its star every 2.8 Earth days and is about 1.2 times the size of Earth and twice as massive. The other foreign world orbits every 5.7 Earth days and is 1.5 times the size of Earth and three times as massive. They're both considered "rocky."

Say hello to your next-door exoplanet neighbors

"Both planets in this system are each considered among the best targets for atmospheric study because of the brightness of their star," Michelle Kunimoto of MIT's Kavli Institute for Astrophysics and Space Research and one of the discovery's lead scientists, said in a statement.

That includes studies that aim to answer questions like, "Is there a volatile-rich atmosphere around these planets? And are there signs of water or carbon-based species?" Kunimoto said -- in other words, a protective layer like the Earth's ozone layer, and living beings like ... humans. "These planets are fantastic test beds for those explorations."

OK, but before you get too excited, the team emphasized that the newly unveiled rocky worlds of interest probably aren't habitable -- they tread really (really) close to their host star, so they're likely too hot to host water. The inner planet, per the study, roasts at an estimated 818 degrees Fahrenheit, and the other runs a balmy temperature of 548 degrees Fahrenheit.


This illustration shows what some exoplanets might look like -- not necessarily the two discussed in this new study.


"We consider that range outside the habitable zone," Kunimoto said.

Still, these worlds could prove invaluable for the overall quest to find habitable exoplanets. In short, they could inform how scientists conduct future studies that might come across planets which are in a habitable zone.

How to find an exoplanet

NASA's TESS has been steadily discovering exoplanets across the universe since its launch in 2018, having already listed an unbelievable number of such extraterrestrial worlds

It essentially works by detecting periodic dips in the luminescence of stars around the universe, because such variations in light could signal that a planet is passing in front of those stars. Imagine looking at a lamp, then seeing a person walk by the lamp to block your view. If you were really far away from the lamp, you might not be able to tell who exactly blocked your view, but you might deduce that someone did, because the light definitely fell for a second. 

It's kind of like that.


An illustration of TESS.


So, in October 2021, Kunimoto found one of these dips while monitoring the satellite's incoming data. They were coming from the star, HD 260655. After lots of other tests, one of which is a well-known gravitational wobble test that looks at whether the light dips are accompanied by a sort of gravitational pull on the star itself, the researchers concluded that, yes, there are two planets orbiting the star at hand.

"We knew we had something very exciting," MIT's Avi Shporer, a member of the discovery team, said in a statement.

"But there might be more planets in the system," Shporer added. "There are many multiplanet systems hosting five or six planets, especially around small stars like this one. Hopefully we will find more." And if the team does find more, "maybe one might be in the habitable zone.

"That's optimistic thinking."