Seven Earth-size planets that could potentially harbor life have been identified orbiting a tiny star not too far away, offering the first realistic opportunity to search for biological signs of alien life outside of the solar system.
The planets orbit a dwarf star named Trappist-1, about 40 light years, or about 235 trillion miles, from Earth. That is quite close, and by happy accident, the orientation of the orbits of the seven planets allows them to be studied in great detail. One or more of the exoplanets, planets around stars other than the sun in this new system could be at the right temperature to be awash in oceans of water, astronomers said, based on the distance of the planets from the dwarf star.
This is the first time so many planets of this kind are found around the same star, said Michael Gillon, an astronomer at the University of Liege in Belgium and the leader of an international team that has been observing Trappist-1.
The findings appear Wednesday in the journal Nature.
Telescopes on the ground now and the Hubble Space Telescope in orbit will be able to discern some of the molecules in the planetary atmospheres. The James Webb Telescope, scheduled to launch next year, will peer at the infrared wavelengths of light, ideal for studying the dimmer longer wavelength light coming from Trappist-1. Comparisons among the different conditions of the seven will also be revealing.
The Trappist-1 planets make the search for life in the galaxy imminent, said Sara Seager, an astronomer at the Massachusetts Institute of Technology who was not a member of the research team. For the first time ever, we don’t have to speculate. We just have to wait and then make very careful observations and see what is in the atmospheres of the Trappist planets.
Even if the planets all turn out to be lifeless, gaining an understanding of the constraints for when life can exist or cannot would also be important new knowledge.Astronomers always knew other stars must have planets, but until a couple of decades ago, they had not been able to spot them. Now they have confirmed more than 3,400, according to the Open Exoplanet Catalog. While the Trappist planets are about the size of Earth give or take 25 percent in diameter the star is very different from our sun.