Earth x 7 = Trappist-1

Astronomers have discovered seven Earth-size planets orbiting a nearby star. Due to their size and their location within the “habitable zone” of their star, it is possible that three of these planets could contain water and, therefore, support life.

The results of the study were published in the journal Nature on Feb. 22, coinciding with a press conference held by NASA announcing the discovery at their Washington D.C. headquarters. The system is called TRAPPIST-1, named for the Transiting Planets and Planetesimals Small Telescope in Chile, which was used to locate the first three of the planets in May 2016. NASA’s Spitzer Space Telescope was used to discover the additional four planets, making TRAPPIST-1 the largest known system of Earth-size planets orbiting the same star.

“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,” Thomas Zurbuchen, associate administrator of the agency’s Science Mission Directorate in Washington, said in a press release.

The TRAPPIST-1 system is a series of firsts for astronomers: it is the first time that three terrestrial planets have been found in the habitable zone of the same star, and it is the first time astronomers have been able to measure the mass and radius of Earth-size planets in a habitable zone. While all seven of the plants could contain water—a key feature of planets that can sustain life—under the right conditions, it is most likely that water would be found on the three planets within the habitable zone.

The star at the center of the system, which gives the system the TRAPPIST-1 name, is considered an ultracool dwarf star, about 2,000 times dimmer than our sun and only slightly larger than Jupiter. Because of this, the habitable zone is much closer to the star, which could explain the compact configuration of the seven planets. (All seven of the planets orbit closer to their star than Mercury does to our sun). TRAPPIST-1 is expected burn for another 10 trillion years, so even if the planets do not currently hold life, there is still potential that they will in the future.

The system is about 40 light-years away, or 235 trillion miles. While this is relatively close by on a cosmic scale, it would still take hundreds of millions of years to get there using current technology. Because they are located outside of our solar system— in the constellation Aquarius, to be exact—they are considered exoplanets.

The planets were discovered through a method called transit photometry, when researchers wait for a planet to pass in front of its host star. In studying the amount of light that is blocked, scientists can see the planet and determine its size. Since 2010, astronomers witnessed 34 transits which they determined came from seven different planets.

The six planets closest to the TRAPPIST-1 star were measured using this system and the density measurements of the planets indicate that they are rocky or terrestrial like Earth, rather than gaseous, like Jupiter. The seventh planet has not yet been measured, but scientists think that could be an icy, “snowball-like” world.

Future research will focus on determining the molecular makeup of the planets’ atmospheres, which could determine whether or not they can sustain life. Things like oxygen could indicate biological activity.

“This is the most exciting result I have seen in the 14 years of Spitzer operations,” said Sean Carey, manager of NASA’s Spitzer Science Center at Caltech/IPAC in Pasadena, California, in a press release. “Spitzer will follow up in the fall to further refine our understanding of these planets so that the James Webb Space Telescope can follow up. More observations of the system are sure to reveal more secrets.” The James Webb Space Telescope will launch at NASA in 2018.

The announcement comes as President Donald Trump has called for an expedited manned mission to the moon, the first since 1972. Originally planned to launch in 2019, Trump has asked NASA to push its launch date up to November 2018. With his obvious focus on returning America to its Cold War glory, it is unsurprising that Trump has set his sights to the moon, but with Congressional budget battles looming, it is unclear whether NASA will find itself on the chopping block or whether it will fulfill expectations of reaching Mars and beyond in the coming years.

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