NASA is declaring the discovery of seven Earth-like worlds as a major leap forward in the search for other life in the universe.
Located some 39 light-years from Earth, the seven exoplanets orbit a single, Jupiter-sized star known as TRAPPIST-1. The star itself is classified as an “ultracool dwarf” because it features surface temperatures of less than 4,400 degrees Fahrenheit.
"The seven wonders of TRAPPIST-1 are the first Earth-size planets that have been found orbiting this kind of star," said Michael Gillon, lead author of the paper and the principal investigator of the TRAPPIST exoplanet survey at the University of Liege, Belgium, said in a press release. "It is also the best target yet for studying the atmospheres of potentially habitable, Earth-size worlds."
New planets hail from the 'Goldilocks Zone'
What's most intriguing is that three planets in TRAPPIST-1 occupy what's known as the "Goldilocks Zone," or the region around a star capable of supporting liquid water on a planet's surface. TRAPPIST-1E is the same size as Earth, at a similar distance from its star, and may have surface temperatures like our own. TRAPPIST-1F is the same size as Earth and may be extremely water-rich. And finally, TRAPPIST-1G is about 13 percent larger than Earth and receives about the same amount of sunlight as Mars.
According the researchers, the distance between these three planets is a few times those between the Earth and moon. The planets are so close, researchers say, that life could transfer from one planet to another in a process called panspermia. If a meteorite were to hit one of the planets, the debris could make its way to another planet. And if bacteria or other forms of life were on that debris, it would then journey to the other planet. Harvard University scientists have determined that this sort of transfer is 1,000 times more likely to occur between the TRAPPIST-1 planets than between Earth and Mars, New Scientist reports.
(And that short distance between planets means, as the illustration below shows, the view of these nearby neighbors from TRAPPIST-1F could be absolutely stunning.)
How we found them
NASA scientists discovered the TRAPPIST-1 star system using observations from the Spitzer Space Telescope. The infrared telescope, launched in 2003, will cease its operations in 2018 and give way to the age of the highly anticipated James Webb Space Telescope. According to the researchers, the James Webb will shed further light on TRAPPIST-1, providing as-yet-unknown critical information about these alien worlds' atmospheres, greenhouse gas compositions, and possible surface temperatures.
As for reaching TRAPPIST-1, researchers during NASA's press conference about the discovery said that some "technological miracles" are still needed before we can think about visiting. Despite it's relatively close distance in astronomical terms of only 39 light-years, it would still take some 44 million years to reach the star system at speeds equivalent to a modern day jet plane.
Could one of these planets be harboring alien life? To hear the excitement in NASA's briefing, the speculation is extremely high that it's possible. If there are civilizations, however, they've yet to reach out. SETI (Search for Extraterrestrial Intelligence) has already listened in on TRAPPIST-1, but has yet to detect any radio signals.
You can see some videos released by NASA of the TRAPPIST system, as well as a VR simulation from the surface of TRAPPIST-1D, below:
Editor's note: This story has been updated with new information since it was originally published in February 2017.