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Wow! Nearby TRAPPIST-1 has 7 planets

Big discovery! NASA’s Spitzer Space Telescope has revealed 7 Earth-sized planets orbiting a tiny star only 40 light-years away. Three of them are firmly in the habitable zone.

At a news conference in Washington D.C. today (February 22, 2017), NASA announced that its Spitzer Space Telescope has observed the first known system of seven Earth-size planets around a single star. Three of these planets are firmly located in what’s called the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water – key to life as we know it. The discovery sets a new record for greatest number of known planets in a star’s habitable zone. After all, our solar system has only two planets in the habitable zone: Earth and Mars. This exoplanet system – called TRAPPIST-1 – has three.

Because they are located outside of our solar system, these planets are scientifically known as exoplanets.

This illustration shows the possible surface of TRAPPIST-1f, one of the newly discovered planets in the TRAPPIST-1 system. Scientists using the Spitzer Space Telescope and ground-based telescopes have discovered that there are seven Earth-size planets in the system. Image via NASA/JPL-Caltech

Only about 40 light-years (235 trillion miles) from Earth, in the direction to our constellation Aquarius, TRAPPIST-1 – classified as an ultra-cool dwarf. It’s so cool that liquid water could survive on planets orbiting very close to it, closer than is possible on planets in our solar system. All seven of the TRAPPIST-1 planetary orbits are closer to their host star than Mercury is to our sun. According to a NASA statement:

The planets also are very close to each other. If a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth’s sky.

The researchers say that the planets might also be tidally locked to the TRAPPIST-1 star. That means that the same side of the planet is always facing the star, therefore each side is either in perpetual day or night. If that’s true, the planets could have weather patterns totally unlike those on Earth, such as strong winds blowing from the day side to the night side, and extreme temperature changes.

The TRAPPIST-1 star, an ultra-cool dwarf, has seven Earth-size planets orbiting it. This artist’s concept appeared on the cover of the journal Nature on February 23, 2017. Image via NASA/JPL-Caltech

According to the study – published today in the journal Nature – all of the TRAPPIST-1 planets are likely to be rocky. Further observations will hopefully reveal whether any have liquid water on their surfaces. The mass of the seventh and farthest exoplanet hasn’t yet been estimated. Scientists believe it could be an icy, “snowball-like” world.

Michael Gillon, lead author of the paper and the principal investigator of the TRAPPIST exoplanet survey at the University of Liege, Belgium. Gillon said in a statement:

The seven wonders of TRAPPIST-1 are the first Earth-size planets that have been found orbiting this kind of star. It is also the best target yet for studying the atmospheres of potentially habitable, Earth-size worlds.

This artist’s concept shows what each of the TRAPPIST-1 planets may look like, based on available data about their sizes, masses and orbital distances. Image via NASA/JPL-Caltech

Following up on the Spitzer discovery, NASA’s Hubble Space Telescope has initiated the screening of four of the planets, including the three inside the habitable zone.

This 360-degree panorama depicts the surface of a newly detected planet, TRAPPIST 1-d, part of a seven planet system some 40 light years away. Explore this artist’s rendering of an alien world by moving the view using your mouse or your mobile device.

Thomas Zurbuchen is associate administrator of NASA’s Science Mission Directorate in Washington. He said in a statement:

This discovery could be a significant piece in the puzzle of finding habitable environments, places that are conducive to life. Answering the question ‘are we alone’ is a top science priority and finding so many planets like these for the first time in the habitable zone is a remarkable step forward toward that goal.

This poster imagines what a trip to TRAPPIST-1e might be like. Image via NASA/JPL-Caltech

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Bottom line: NASA’s Spitzer Space Telescope has observed 7 Earth-sized planets orbiting a tiny star called TRAPPIST-1. Three of them are firmly in the habitable zone.

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Eleanor Imster

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