NASA announced on Feb. 22 the discovery of Seven Earth-like planets orbiting a star called Trappist-1, with three existing in the habitable zone—meaning liquid water can cool on the planet’s surface.
UTSA Physics & Astronomy Associate Professor Dr. Chris Packham said of the discovery, “It’s a tremendously exciting time to be an astronomer, with the pace of discovery regarding so-called exoplanets increasing rapidly. Surely it cannot be too much longer until we discover the tell-tale signatures of life on other planets, albeit perhaps only microbial life. All of mankind’s existence we have asked, ‘are we alone?’ In our generation, we may be able to truly answer that question.”
NASA made this discovery with the Spitzer space telescope, determining the seven Earth-like planets orbited around a star called Trappist-1 about 40 light years away from Earth. NASA found that one planet’s atmosphere suggests a water-rich composition after reading data from measurements derived by a technique called transmission spectroscopy. This technique can detect different chemical species in a planet’s air, such as water, methane or oxygen.
Concerning the possibility of life on any of these planets, UTSA Assistant Professor of Geology Dr. Marina Suarez said, “We know that life exists in some amazing places on Earth, so I think it is not difficult to think life could exist on an Earth-like planet elsewhere in the universe.”
Trappist-1, the star home to these seven Earth-like planets, is an ultracool dwarf star. According to Dr. Gillon, this type of star is “much cooler and much smaller than our Sun.” Trappist-1 was discovered in May 2016, with three planets, sparking the study that lead to finding four more planets.
The seven planets orbiting Trappist-1 are all within a region about five times smaller than the distance between Mercury and our Sun.
UTSA Physics & Astronomy Professor Dr. Eric Schlegel described the importance of this distance from a visitor’s perspective. He asks you to imagine yourself walking one of the planet’s surface while reading a good book, saying, “you will be able to see the other planets reasonably well because they are so close, but the ‘reading light’ provided by (Trappist-1) will be quite red.”
This monumental discovery comes 22 years after astronomers found the first planet outside of our solar system called 51 Pegasi b. In 2013, astronomers predicted the existence of as many as 40 billion Earth and super-Earth-sized planets within habitable zones. NASA’s Kepler space telescope discovered the first Earth-sized planet in a habitable zone on July 23, 2015.