New Alien Planet Found By NASA’s Exoplanet Hunter TESS


NASA’s new exoplanet hunter called TESS – the abbreviation for Transiting Exoplanet Survey Satellite – is pretty good at discovering alien planets outside our solar system. We call them exoplanets, and scientists want to learn more about them and their composition – leading to solving the greatest question on Earth: are we the only life forms in this galaxy?

TESS has discovered a small and cool planet outside our solar system. But these characteristics made scientists wonder.

The planet is known as HD 21749b, and it is the third one discovered by TESS, which began its work at the end of summer 2018.

HD 21749b is orbiting its star in 36 days, and despite being this close to it, the small planet is quite cool – it only reaches about 300 degrees Fahrenheit. The leader of this discovery, Diana Dragomir, who is a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research, stated a few words about this planet:

It’s the coolest small planet that we know of around a star this bright. We know a lot about atmospheres of hot planets, but because it’s very hard to find small planets that orbit farther from their stars, and are therefore cooler, we haven’t been able to learn much about these smaller, cooler planets. But here we were lucky, and caught this one, and can now study it in more detail.


HD 21749b is nothing like our Earth. Dragomir added that the planet might be made of gas:

We think this planet wouldn’t be as gaseous as Neptune or Uranus, which are mostly hydrogen and really puffy. The planet likely has a density of water, or a thick atmosphere.

While scientists say that this planet is small, it actually is almost as big as three Earths and 23 times more massive than Earth. This means that HD 21749b is a “sub-Neptune,” but it is still considered almost Earth-like in terms of size.


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