NASA announced on Wednesday that Spitzer Space Telescope has revealed “the first known system of seven Earth-sized planets around a single star,” including three planets located in the star’s habitable zone.
Never has there been a discovery outside of our solar system with so many habitable-zone planets around a single star. NASA states that all seven planets could have liquid water, but the three planets in the habitable zone have the highest likelihood, meaning that their environments would be conducive to life.
All seven planets orbit the TRAPPIST-1 star, an ultra-cool dwarf in the Aquarius constellation, and are about 40 lightyears from Earth. The system is named after The Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile, which discovered three of the planets in the system. Spitzer was then used along with ground-based telescopes to confirm their existence as well as discover the remaining planets.
The system’s planets are situated closer to their star than Mercury is to our sun, and they appear to be tidally locked, meaning that the same side of the planet is always facing the sun, leaving one side in perpetual darkness. According to NASA, this could mean their weather patterns are completely different from Earth.
Hubble is now reviewing the three planets inside the habitable zone, as well as one additional planet, to determine whether they have hydrogen-dominated atmospheres. Hubble’s work has ruled this out in the two closest to the star, suggesting that they are rocky planets.
Kepler is also studying the system by “making measurements of the star’s minuscule changes in brightness due to transiting planets” to refine the properties of the planets.
Scientists, however, are most excited about the launch of the James Webb Space Telescope in 2018, a joint project with Canada and Europe. The telescope will be more sensitive than current telescopes and able to detect the chemical components of a planet’s atmosphere, temperatures and surface pressures, all which are important in determining the habitability of each of the planets. The telescope will also be able to detect longer wavelengths and see fainter objects in the solar system at a rate of 10 to 100 times fainter than Hubble. These are all reflected in the project’s four goals.
To find out more about the TRAPPIST-1 system, visit https://exoplanets.nasa.gov/trappist1/.
To read NASA’s official press release, visit https://www.nasa.gov/press-release/nasa-telescope-reveals-largest-batch-of-earth-size-habitable-zone-planets-around.
To read the results published in Nature journal, visit http://www.nature.com/nature/journal/v542/n7642/full/nature21360.html.