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Exoplanets: Earth is not alone

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By Jeremy Wilks
Exoplanets: Earth is not alone

There are probably many millions of Earth-like planets across the Milky Way that we could potentially walk around on, with liquid water and maybe even bacterial life on the surface. In fact, exoplanets of all kinds are everywhere. The number is as infinite as the stars in the heavens.

The latest findings about these planets around TRAPPIST-1 just serves to feed the interest in this growing field of astronomy. Ask any exoplanet scientist about the potential for intelligent life outside our solar system and you’ll hear the familiar ‘Yes, but…’ answer. Yes, we think there might be, but don’t quote us on that, because we can’t see with enough precision.

But that’s changing. Astronomers are now able to use more and more powerful satellites and telescopes to detect these exoplanets, if not actually observe them directly. As we reported on in January’s edition of Space, hunting for exoplanets is still extremely difficult. One of the key reasons the TRAPPIST-1 planets were found is that they orbit fast and close to their dim dwarf star, and so they are relatively easy to spot. A planet like Earth, with a star as bright as the Sun, is really difficult to observe because it’s so faint compared to the light around it, and would only pass in front of it once every year.

Looking forward, we can expect an explosion in exoplanet discovery. The JWST telescope should be able to identify water in the atmospheres of these planets, while the Swiss-ESA telescope CHEOPS will look at stars that we already know to be home to Jupiter-like planets, to look for smaller bodies comparable to Earth. Then ESA’s Plato mission, set for launch in 2024, will look directly for rocky planets in the habitable zone around Sun-like stars. In the same year a big new set of eyes will be looking up from here on Earth, in the form of ESO’s superbly named European Extremely Large Telescope. Built in Chile, it should be able to observe exoplanets directly, and may be the instrument that detects the most convincing signs of alien life.