NASA telescope identifies Earth-sized planet in habitable zone

A NASA telescope just discovered a planet in the habitable zone.
Image: NASA Goddard Space Flight Center

Humans have long been pursuing the idea of finding an Earth-like planet somewhere else in space. Yet, despite the fact that astronomers have found celestial bodies in so-called “habitable zones,” none of them are similar in size to the blue planet we inhabit. That is, until their most recent discovery.

NASA’s planet-hunting telescope recently identified an Earth-sized planet that may contain water on its surface. The Transiting Exoplanet Survey Satellite (TESS) has a long history of identifying potentially habitable planets, but none are as exciting as this one.

In the Habitable Zone

The Earth’s position relative to the sun is just right to support life. If it were a little further away, it would be too cold for our diverse array of plants and animals. Water would also freeze. If it were closer, things on the surface would simply overheat and water would boil away. As it happens, not many planets find themselves in this situation. Thus, scientists have given it the name “habitable zone.”

In terms of Earth, this means that everything needed to support life is present. For other planets in the habitable zone of their own star, scientists believe that the conditions for life may be appropriate. Though it’s impossible to confirm a planet’s environment without visiting, this belief marks them as targets for more research and observation.

The planet recently discovered by TESS is the outermost in its solar system and rests just inside the habitable zone. It has been given the name TOI 700 d.

Interestingly, astronomers have known about the TOI 700 system for a while. However, they originally believed that its sun was as big as Earth’s. This meant that the planets also appeared to be larger and hotter.

Once TESS discovered that TOI 700’s sun is about 40 percent smaller than ours, the calculations about the orbiting planets also changed. Ultimately, this led to the realization that TOI 700 d is the same size as Earth.

Brewing Excitement

The discovery of TOI 700 d has led to a great deal of excitement in the scientific community. It is the first of its kind. No other Earth-sized planet has ever been found in a habitable zone.

Emily Gilbert, a graduate student at the University of Chicago said in a statement, “In 11 months of data, we saw no flares from the star, which improves the chances TOI 700 d is habitable and makes it easier to model its atmospheric and surface conditions.”

Sadly, the TOI 700 system is more than 101 light-years away from Earth. This means that humans won’t be visiting to find out if TOI 700 d is habitable anytime soon. Still, knowing that such a planet exists is exciting.

Researchers are now trying to learn more about TOI 700 d by conducting studies to determine what type of atmosphere and composition the planet may have.

Joseph Rodriguez is an astronomer at the Center for Astrophysics at Harvard and Smithsonian. He says, “Given the impact of this discovery—that it is TESS’s first habitable-zone Earth-sized planet—we really wanted our understanding of this system to be as concrete as possible.”


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