Humanity has long been on a quest to discover other habitable planets in the universe, and this effort has been gaining even more significance as we are consuming up our own globe. But what if we found a solar system with not just one habitable planet, but a whole treasure trove of them?
Well, we might as well be getting there. NASA‘s Spitzer Space Telescope has recently discovered the first known system of seven (!) Earth-size planets around a single star. Three of these planets in the solar system named TRAPPIST-1 are firmly located in the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water.
The discovery sets a new record for the greatest number of habitable-zone planets found around a single star outside our solar system. All seven planets could have liquid water – key to life as we know it – under the right atmospheric conditions, but the chances are highest with the three in the habitable zone (which are rocky in nature). And at about 40 light-years (235 trillion miles) from Earth, the system of planets is relatively close to us, in the constellation Aquarius. So who knows? One day we might even get there.
Now look around on the surface of the third planet from the red TRAPPIST-1 star with the help of the amazing 360 panorama below. From here, the star looms larger than our sun and its light casts a red glow across the sky. Look up, and you may catch a glimpse of its six sister planets, as visible as our moon is from Earth.
Some interesting facts about the TRAPPIST-1 system from NASA’s website:
In contrast to our sun, the system’s star – classified as an ultra-cool dwarf – is 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. The planets also are so close to each other that if a person was standing on one of them, they could look up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth’s sky.
The planets could also be tidally locked to their star, meaning the same side of the planet always faces it, basking in perpetual daylight (with the other side shivering in eternal darkness). This could mean they 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.
Spitzer (and in its wake, the Hubble, and Kepler space telescopes) will help astronomers plan for follow-up studies using NASA’s James Webb Space Telescope, which has just been built. With much greater sensitivity, Webb will be able to detect the chemical fingerprints of water, methane, oxygen, ozone, and other components of a planet’s atmosphere. Webb also will analyze the planets’ temperatures and surface pressures – key factors in assessing their habitability.
“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. “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.”