Facts about the seven earth-size planets

seven earth-size planets
Scientists have spotted seven earth-size planets around a nearby star, they have never seen anything like this before. Image credit: Science News

Scientists have spotted seven earth-size planets around a nearby star, they have never seen anything like this before. According to them, it could all harbor water and possibly life and that’s the biggest cluster of planets like this yet to be found.

The exoplanets circle the star TRAPPIST-1, it lies just 39 light-years from the Earth. The study team members stated that speculations about the alien world’s life-hosting potential should soon be informed by hard data. They are also expecting that within a few years, they will know a lot more about these planets and if there is a chance to live there within a decade.

Researchers have focused on finding Earth-sized planets with the right temperatures where it is indeed possible to live there. This has also been the first time that so many Earth-sized planets found around the same star. The diameter of TRAPPIST-1 is about 8 percent of the sun’s size, and so that makes its Earth-sized planets appear large as they parade past.

The lead researcher Michael Gillion said that since TRAPPIST-1 is so small and cool, its “habitat zone” is very close to the star and the three planets are properly positioned for liquid water.  These planets also form a very compact system and they could have some liquid water and maybe life.

Even if the planets do not have life now, it could still evolve. The TRAPPIST-1 is at least 500 million years old yet it has an estimated lifespan of 10 trillion years. In comparison to that, the sun is about halfway through its estimated 10-billion-year life.

Astronomer Ignas Snellen, with the Netherlands’ Leiden Observatory wrote in a related essay in Nature that in a few billion years, when the sun has  run out of fuel and solar system has ceased to exist, TRAPPIST-1 will still be an infant star.

These seven planets were detected by watching how their star dims as the planets pass in front from the Earth’s vintage point. The amount of starlight blocked calculated by each transit indicates that all of these seven planets have roughly the same radius as Earth. Dips in starlight can also reveal how fast the planets orbit the star: the innermost one makes a round trip in 1.5 Earth days while the outermost one takes about 20 days.

Finding these seven earth-sized planets suggests that Earth cousins may  be more common than expected .  Studying the atmospheres of theses planets could reveal if they have life. It could also be possible to study the planet’s atmosphere with the Hubble Space Telescope or its successor. James Space Telescope to lunch on 2018.

Here’s a quick look:

Age of Aquarius

This star system is less than 40 light-years from Earth, or 235 trillion miles away, in the constellation Aquarius. At the hub is a small, faint star known as Trappist-1. Seven planets circle Trappist-1, with orbits ranging from 1 ½ to 20 days. If Trappist-1 were our sun, all these planets would fit inside the orbit of Mercury. That’s how close they are to their star and why their orbits are so short. The planets have no real names. They’re only known by letters, “b” through “h.” The letter “A” refers to the star itself.

Goldilocks zone

Three of the planets are smack dab in the so-called habitable zone, also known as the Goldilocks zone, where conditions are just right for water and life to flourish — not too much and not too little stellar energy. The four other planets are tantalizingly close to the Goldilocks zone— so close that they, too, could harbor water and potentially life. But just because a planet is in this sweet spot, doesn’t mean life exists or ever did. If aliens were observing our solar system from the Trappist-1 network, they might be saying, “Hey, there are three habitable planets there, Venus, Earth and Mars,” said Sara Seager, a Massachusetts Institute of Technology astrophysicist who did not take part in the study. The point is, “let’s wait and see what’s out there,” she cautioned.

How’s the view?

Trappist-1, one of numerous ultracool dwarf stars out there in the galaxy, glows red. If you were to stand on one of the planets, the star might appear to be salmon-colored. Its planets are clumped so closely together, they would appear twice as big as our moon in the sky. The temperature could be pretty similar to Earth as well, at least on one of these planets.

Now what?

Scientists need to study the atmospheres of these almost assuredly rocky planets before jumping to any conclusions about water and life. The Hubble Space Telescope already is on the case. The still-under-construction James Webb Space Telescope will join in once it’s launched next year. The Webb will search for gases that might be a byproduct of life: oxygen, ozone and methane. Scientists say it should take five years to get a handle on all these atmospheres, and figure out whether water — and maybe life — are present. Altogether, astronomers have confirmed close to 3,600 planets outside our solar system since the 1990s, but barely four dozen are in the potential habitable zone of their stars, and of those, just 18 are approximately the size of Earth.



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