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NASA has found hundreds of exoplanets – and is expected to find thousands

At just 50 light-years away from Earth, there are about 1,560 stars, probably orbited by several thousand planets. About one thousand of these extrasolar planets – so-called exoplanets – can be rocky and have an earth-like composition. Some can even accommodate life. Over 99 percent of these alien worlds are still undiscovered – but that will change soon.

NASA's new Exoplanet Hunter Space Telescope TESS is looking for potentially habitable planets near our solar system. TESS – orbiting Earth every 13.7 days – and ground-based telescopes are ready to find hundreds of planets over the next few years. This could change the astronomers' understanding of alien worlds around us and provide goals that can be scanned for signatures of life with next-generation telescopes.

In just over a year, TESS has identified more than 1

,200 planetary candidates, 29 of which are already superior to planets as planets. Given TESS's unique ability to simultaneously search tens of thousands of stars for planets, the mission is expected to produce over 10,000 new worlds.

These are exciting times for astronomers and especially for those of us exploring exoplanets. We are members of the planetary hunting project EDEN, which also supports the work of TESS. We use telescopes on the ground and in space to search for exoplanets to understand their properties and their potential for housing life.

Undiscovered Worlds Around Us

Worlds around us are waiting to be discovered. Take, for example, Proxima Centauri, a modest, faint red star invisible without a telescope. It is one of over a hundred billion such stars in our galaxy, unobtrusive, except for its status as our nearest neighbor. Orbiting Proxima is a fascinating but mysterious world called Proxmia b that was discovered in 2016.

Scientists know surprisingly little about Proxima b. Astronomers call the first planet "b" discovered in a system. This planet has never been seen with human eyes or with a telescope. However, we know that it exists because of its attraction to the star of hosts, causing the star to wobble very slightly. This slight wobble was found in measurements taken by a large international group of astronomers based on data from multiple ground-based telescopes. It is very likely that Proxima b has a rocky composition that resembles that of Earth, but has a higher mass. It receives about the same amount of heat as the earth from the sun.

And that's what makes this planet so exciting: it's in the "habitable" zone and may have properties similar to Earth's, like a surface or liquid of water and – who knows? – maybe even an atmosphere with telltale chemical signs of life.

The NASA TESS mission started in April 2018 to look for other planets the size of the Earth, but with a different method. TESS looks for rare dimming events that occur when planets pass in front of their host stars and block starlight. These transit events not only indicate the presence of the planets, but also their size and orbit.

The search for a new exoplanet in transit is a great challenge for astronomers like us, because unlike those found by the star's wobbly movements, worlds observed during transit can be examined for their density and atmospheric composition to determine.