Astronomers Dscover seven Earth-sized planets orbiting a nearby star

Astronomers have found at least seven Earth-sized planets orbiting the same star 40 light-years away, according to a study published Wednesday in the journal Nature. The findings were also announced at a news conference at NASA Headquarters in Washington.

This discovery outside of our solar system is rare because the planets have the winning combination of being similar in size to Earth and being all temperate, meaning they could have water on their surfaces and potentially support life.

"This is the first time that so many planets of this kind are found around the same star," said Michaël Gillon, lead study author and astronomer at the University of Liège in Belgium.

The seven exoplanets were all found in tight formation around an ultracool dwarf star called TRAPPIST - 1

 Estimates of their mass also indicate that they are rocky planets, rather than being gaseous like Jupiter. Three planets are in the habitable zone of the star, known as TRAPPIST-1e, f and g, and may even have oceans on the surface. 

The TRAPPIST-1 star, an ultracool dwarf, has seven Earth-size planets orbiting it.

NASA discovers seven Earth-size planets: Here’s all you need to know

First: A system of seven planets in a system called TRAPPIST-1 is the highlight of this discovery. NASA has named the system of planets after the ‘Transiting Planets and Planetesimals Small Telescope,’ which is located in Chile. This telescope first discovered three of the planets in this system in May 2016.

Second: The star in TRAPPIST-1 is classified as an ultra-cool dwarf, which NASA points out is in contrast to our Sun. The ultra-cool dwarf has a lower mass than the Sun, and also much lower temperatures. What this means is even if planets are orbiting close to the dwarf sun, it is so cool that liquid water will be able to survive on these planets.

The ultracool star shines 200 times dimmer than our sun, so you’d have twilight at all times on these planets, and the star glows red. The Sun is no bigger than the planet Jupiter in our solar system.

NASA’s telescopes show the planets are closer to the host star than planet Mercury is to our Sun. According to NASA’s own press statement, “If a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighbouring worlds, which would sometimes appear larger than the moon in Earth’s sky.”

Third: Unlike Earth, which rotates on its axis, the planets are “tidally locked to the star.” This means that one side of the planet has only day, and one side has only night. It also means the weather conditions are unlike what we experience on Earth.

Fourth: The planets are Earth-sized. “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 in NASA’s press statement. “It is also the best target yet for studying the atmospheres of potentially habitable, Earth-size worlds.”

Using the Spitzer data, NASA’s team calculated the sizes of the seven planets, and have developed the first estimates of the masses of six of them. NASA predicts that based on the density, the planets are rocky, though they can’t confirm the presence of water yet. This will only be determined with more observations. It looks like the seventh planet is an icy, snow world, which might remind some of Pluto in our solar system.

Fifth: Scientists said they need to study the atmospheres before determining whether these rocky, terrestrial planets could support some sort of life. But it already shows just how many Earth-size planets could be out there. Two planets closest to the host star have already shown signs of no puffy atmosphere, meaning they are potentially rocky in nature.

Sixth: TRAPPIST-1 holds the record for the greatest number of habitable-zone planets found around a single star outside our solar system.

he discovery of the planets doesn’t mean the end of the job for NASA. The space agency’s Hubble Space Telescope is already screening four of the planets, three which are inside the habitable zone. Spitzer, Hubble and Kepler will do initial surveys of the exoplanets ahead of NASA’s launch of the James Webb Space Telescope in 2018.

According to NASA’s statement, the new Web telescope will “detect the chemical fingerprints of water, methane, oxygen, ozone, and other components of a planet’s atmosphere,” along with temperature, surface pressure, etc to know if these planets can be inhabited by life in the future.