Exoplanet - TOI-700 d

NASA's Transiting Exoplanet Survey Satellite (TESS) has just bagged its first potentially habitable planet discovery, named TOI-700 d, which orbits a red dwarf star about 100 light years away from earth. So what is it about this planet that makes it habitable?

Exoplanet - TOI-700 d

First off, it receives 85% the amount of energy from its star that Earth gets from the Sun, which puts it safely in the habitable zone. Despite receiving less energy, average surface temperatures might be closer to that of Earth, given that red dwarfs radiate most of their energy in the infrared.

Exoplanet - TOI-700 d

The planet is 1.22 times the size of Earth and probably rocky. Size is important, if the planet were bigger, say around 1.6 times larger than Earth, it might not have a solid surface to live on.

The star it orbits appears to be rather quiet. The TESS satellite observed this star for nearly a year and did not detect any stellar flares. Of course flares are bound to happen at some point, but their non-detection in the TESS data suggest that they are a rare occurrence. This fact is a plus for habitability, as strong flares can potentially erode away a planet’s atmosphere or sterilize the surface.

However, even though this planet is potentially habitable, it would still be different from Earth in many ways. The first and most obvious feature would be that TOI-700 d is tidally locked to its star. One side of the planet gets constant sunlight, while the other side is in permanent darkness. On the day side, water from oceans (if there are any) could evaporate and form a giant cloud layer, which has the potential to cool down the surface and make it more livable.

It remains to be seen what 700 d is made of. Researchers have generated models based on the size and type of star in order to predict 700 d’s atmospheric composition and surface temperature.

In one simulation, NASA explained, the planet is covered in oceans with a “dense, carbon dioxide-dominated atmosphere similar to what scientists suspect surrounded Mars when it was young. In another, the planet is dry and cloudless”. Researchers modeled 20 different versions of TOI 700 d, any of which might be correct.

In summary, I’d say that TOI-700 d is definitely one of the better candidates for being potentially habitable.

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