In a press conference today, NASA scientists revealed an extraordinary new discovery – the first known system of seven rocky, Earth-sized planets orbiting a single star. Three out of the seven planets are situated at the perfect distance from the sun to potentially harbor liquid water, making them habitable for life as we know it.
This is the largest number of habitable-zone planets ever found around a single star outside our own solar system. It’s important to note that simply because these planets could potentially hold liquid water doesn’t mean that they do – but the likelihood is higher given their location. The planets are orbiting an ultra-cool dwarf star called TRAPPIST-1, located about 40 light years (or 235 trillion miles) from Earth in the Aquarius constellation.
The system is named after the TRAPPIST (The Transiting Planets and Planetesimals Small Telescope), located in an observatory in Chile. In May 2016, TRAPPIST researchers announced they’d discovered three planets in the system. NASA’s Spitzer Space Telescope was able to confirm those exoplanets’ existence and that of four additional planets. The results of NASA’s study have been published in the journal Nature today.
What’s especially interesting about the TRAPPIST-1 system is how different its habitable zone is from that of systems like our own. Because the star is much cooler than our sun, planets much closer to the sun than Earth could potentially have liquid water. In fact, all seven of TRAPPIST-1’s planets are closer to the star than Mercury is to our own sun, and each of the planets are so close to one another they would appear in one another’s skies the same way the moon appears in ours.
NASA scientists also speculate the planets may be tidally locked, so that the same side of the planet is always facing the star, casting one half of the planet in permanent daylight and the other in perpetual night. This could cause weather patterns unlike anything we’ve ever seen before on Earth, and extreme differences in temperature from one side to the other.
The Spitzer telescope was able to detect the presence of the planets by observing the infrared wavelengths emitted by the star over a period of 500 hours. Each time a planet crossed in front of the star, the telescope could detect changes in the star’s brightness. NASA also followed up with a study using the Hubble Space Telescope to determine whether the planets were rocky, or likely had a “puffy” atmosphere like those of our own system’s gas giants.
There’s still much about these planets we simply do not know, but studies will continue to help NASA learn more about them. Right now, the Kepler space telescope is also recording observations about the system, which will reveal more properties about the exoplanets in March. NASA’s new James Webb Telescope will also be pointed toward TRAPPIST-1 after its launch in 2018, and will analyze the planets’ temperature, surface pressure, and atmospheric makeup – all key factors that will reveal whether these worlds can actually sustain life.
Images via NASA