Rather, the Transiting Exoplanet Survey Satellite, was launched in 2018 aboard a SpaceX Falcon 9. Since then, it has been pointed outward toward distant stars in search of exoplanets.

It’s primary mission lasted two years and now the data has been collected and published. TESS found 2241 exoplanet candidates orbiting the brightest stars in the sky.

TESS discovered these exoplanets (or TOI’s which stands for TESS Object of Interest), by utilising the transit method. Essentially, TESS observed bright stars over a period of time, approximately 27 days, and watched for dips in the light being cast out by the stars.

Any dip that repeats itself at regular intervals can possibly signal that it is an exoplanet orbiting the star.

The Transit Method Credit: Universe and Astronomy, YouTube

And within those 2241 TOI’s there have already been some incredible discoveries.

A phenomenon previously thought to be impossible, and reserved for science fiction has been discovered. It was first detected by the Kepler satellite, designated KOI-5 and then tagged against by TESS as TOI-1241. It is a three star system with an exoplanet orbiting one of them. It took years of data collection and hard work by a group of scientist to come to this conclusion and a peer-reviewed is on its way.

But that isn’t all that TESS has discovered, within the article published alongside the catalog of Objects of Interest, the authors describe a few of their most startling discoveries.

It’s long been assumed that when our sun expands into a red giant, that all the planets orbiting it will be consumed. And when the sun shrinks back down into its final stage, that of a white dwarf, there would be no planets orbiting it any longer, merely remnants. However, thanks to TESS and the team behind it, a white dwarf has been discovered with a giant planet orbiting it. This planet, designated as TOI 1690, orbits the white dwarf once every 1.4 days and its close proximity to the white dwarf suggests that it has moved into that near orbit long after the star collapsed from its red giant state. This means that long ago TOI 1690 had a far larger orbit than it does today, otherwise it would have been consumed.

A planet orbiting in the habitable zone of its star has also been discovered by TESS. TOI 700d is an earth sized planet orbiting its red dwarf every 37.42 days. As the star of this system is a lot cooler than earth, the habitable zone is closer, hence the smaller orbital period. Two other planets also exist in this system, however they are both interior to 700d and therefore are too close to the star to be considered habitable.

Those three examples of TOI that TESS has shed light on barely scratch the surface of the 2241 that it has found. It’s true that some of these TOI’s may not be exoplanets, however, the majority will be and that is an exciting prospect; the more we learn about the planets out there in the galaxy, the more we can learn about the ones in our very own solar system.

It’s no surprise to people who read this blog that I am enamoured with the idea of space in general, but exoplanets specifically. The idea that we may have discovered 2241 more makes me giddy with excitement and I hope that reading about the latest discoveries does the same for you.

Further Reading:

[2103.12538] The TESS Objects of Interest Catalog from the TESS Prime Mission (arxiv.org)


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