At about 40 light-years (235 trillion miles) away from our solar system, an international team of astronomers (NASA and the European Southern Observatory team) have discovered seven Earth-sized worlds, which have been spotted orbiting closely around a tiny, a Jupiter-sized ultra-cool dwarf star called TRAPPIST-1 in the constellation of Aquarius, according to a study published Wednesday in the journal Nature. The findings were announced by NASA, they made the announcement in a highly anticipated press conference at NASA Headquarters in Washington after triggering much speculation over their big “discovery beyond our Solar System”.

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

These seven Earth-sized planets are scientifically known as exoplanets, have been discovered outside our solar system by NASA’s Spitzer Space Telescope. Tiny, super-cool stars (known as red dwarfs) have become popular targets for exoplanet hunters; it’s easier to study the planets around them. This exoplanet system, dubbed as TRAPPIST-1, has been observed by TRAPPIST (The Transiting Planets and Planetesimals Small Telescope) in Chile.

Michael Gillon leads the TRAPPIST collaboration, which hunts for planets using two 60-centimetre telescopes: one in Morocco and one in Chile. Last spring, the University of Liege’s Michael Gillon and his team reported finding three planets around the star, known as TRAPPIST-1. The telescope did not see the planets directly, but recorded the shadows they cast as they crossed the face of the star. Upon further observation, however, NASA’s Spitzer Space Telescope revealed the star is home to seven.

“I would have never predicted this. It’s beyond anything I could have dreamt of,” Nikole Lewis, an astronomer at the Space Telescope Science Institute in Baltimore, said in a video accompanying NASA’s announcement about the “treasure trove” discovery.

Another artist’s impression of the view from a TRAPPIST-1 planet’s surface. In 2016, astronomers announced the discovery of three Earth-size worlds in the TRAPPIST-1 system. Additional observation upped eventually upped that tally to seven. Photo Courtesy:- ESO

All exoplanets are thought to be mostly made up of rock and could potentially support liquid water on their surfaces. Of the seven rocky exoplanets, three planets are close to the star, and may be a little too hot to hold much liquid water. One planet of the seven exoplanets may be an ice world. And other three planets (e, f and g) lie in what is known as the “Goldilocks Zone” — a habitable region around the parent star- under the right atmospheric conditions (neither too hot nor too cold), in which a planet is most likely to harbor water, and they may have strong potential to sustain life as we know it.

The planets “e,” “f,” and “g” — marked in green are directly in the “habitable zone” of this star system. Photo Courtesy:- NASA
This illustration shows the possible surface of TRAPPIST-1f, one of the newly discovered planets in the TRAPPIST-1 system. Scientists using the Spitzer Space Telescope and ground-based telescopes have discovered that there are seven Earth-size planets in the system. Photo Illustration: Nasa/JPL-Caltech

Study suggests at least the inner six exoplanets appear to have Earth-like masses, have pleasant climates (surface temperatures) ranging between a life-friendly 0 to 100°C (32 to 212°F) and they are made of rock. Scientists say the system is an ideal laboratory for studying alien worlds and could be the best place in the galaxy to search for life beyond Earth. Google has marked the Earth-shattering discovery with a Doodle, featuring the seven planets squeezing into view on the earth’s telescope.

Discoveries of exoplanets. Photo Courtesy:- Google

“The star is so small and cold that the seven planets are temperate, which means that they could have some liquid water and maybe life, by extension, on the surface,” said Michael Gillon, a lead author of the paper and the principal investigator of the TRAPPIST exoplanet survey at the University of Liege, Belgium.

Out of this world.. The TRAPPIST-1 red dwarf star solar system and its seven ‘Earth-like’ planets compared to Jupiter and its moons, and our own Solar System. Photo Source:- NASA

The planets in the extra solar system, travelling around the TRAPPIST-1 star, with orbits ranging from one and a half to 20 days. The planets have no real names, they’re known by letters and are named in order of their distance from the star. Individually they are called TRAPPIST 1b, c, d, e, f, g and h. The letter “A” refers to the star itself. The whole system is pretty compact too, the closest planet takes just 1.5 Earth days to complete one orbit, while the farthest planet takes around 20 days to circle the star. Because of this, they’re all a super tight bunch.

The seven planets in the TRAPPIST-1 system range in mass from 75 percent to 110 percent that of Earth. At least three of the worlds likely have surface temperatures that allow liquid water to exist, scientists say. Photo Courtesy:- NASA/JPL-Caltech

NASA said that all seven exoplanets are closer to TRAPPIST-1 than any planet in our solar system is to our sun, they also are clumped very close to each other. That means that if you were standing on one of the exoplanet’s surface, the neighbouring planets in the sky would at times appear larger than our Moon does to us.

Some 40 light-years from Earth, a planet called TRAPPIST-1e offers a heart-stopping view: brilliant objects in a red sky, looming like larger and smaller versions of our own moon. But these are no moons. They are other Earth-sized planets in a spectacular planetary system outside our own. These seven rocky worlds huddle around their small, dim, red star, like a family around a campfire. Any of them could harbor liquid water, but the planet shown here, fourth from the TRAPPIST-1 star, is in the habitable zone, the area around the star where liquid water is most likely to be detected. Photo Courtesy:- (NASA-JPL/Caltech)

Because the seven alien worlds orbit so tightly, it’s thought that the planets might all affect each other, and could even be tidally locked, with one face constantly pointed towards their host star, just as Earth’s moon only shows the “near side” to us. That tidal locking could also do some strange things to the temperature gradients on the planet, which NASA says makes it possible that liquid water could exist on any of them under the right conditions. And powerful gravitational tugs, both from TRAPPIST-1 and neighboring planets, could heat up the worlds’ insides considerably, leading to lots of volcanism, especially on the innermost two worlds, the scientists added.

All of the seven exoplanets discovered around TRAPPIST-1 orbit much closer to their star than Mercury does to the Sun, as shown here in this comparison of the TRAPPIST-1 orbits with the Galilean moons of Jupiter and the planets of the inner solar system. But because TRAPPIST-1 is far fainter than the Sun, the worlds are exposed to similar levels of irradiation as Venus, Earth and Mars. Photo Courtesy:- ESO/O. Furtak
This diagram compares the sizes of the newly discovered planets around the faint red star TRAPPIST-1 with the Galilean moons of Jupiter and the inner Solar System. All the planets found around TRAPPIST-1 are of similar size to the Earth. Photo Courtesy:- (O. Furtak / European Southern Observatory)

All newly discovered planets are about the same size as Earth or Venus, or slightly smaller. Relative to Earth, the planet with the largest radius (1g) is 1.13 times the size of our planet as big as the Moon in the sky and the smallest radius (1h) is 0.76 times the size of the Earth. Planet 1c (0.41) has the largest mass relative to Earth and 1e has a mass 0.62 of Earth.

The top row shows an artist’s conception of the seven planets of Trappist-1 with their orbital periods, distances from their star, radii and masses as compared to those of Earth. The bottom row shows data about Mercury, Venus, Earth and Mars. Photo Illustration: (NASA/JPL-Caltech)

The ultracool star at the heart of this solar system would shine with a feeble light about 200 times dimmer than our yellow sun, a perpetual twilight as we know it. And the star would glow red – maybe salmon-pink colored, the researchers speculate. Due to the parent star is so dim, the planets are warmed gently despite having orbits much smaller than that of Mercury, the planet closest to the sun.

Thomas Zurbuchen, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington, said: “This discovery could be a significant piece in the puzzle of finding habitable environments, places that are conducive to life.” “Answering the question ‘are we alone’ is a top science priority and finding so many planets like these for the first time in the habitable zone is a remarkable step forward toward that goal.”

Although at least some fraction of each planet could harbor liquid water, it doesn’t necessarily follow that they are habitable. To figure this out, astronomers will try to detect the components of each planet’s atmosphere. One way to do that is to look at the star’s light as it passes through the gas circulating around the planet. Different gases will filter the light in different ways, giving astronomers a good idea of what compounds surround each world. That would make it much more challenging for life to thrive.

NASA released a 360º simulation of what it would be like to stand on one of the potentially habitable planets.

Other astronomers are already using the NASA’s Hubble Space Telescope, Spitzer and Kepler to hunt for atmospheres on the TRAPPIST-1 planets. The Hubble Space Telescope should be able to detect methane and water in the alien air (the planets’ atmospheres), but both can be produced without life. Such speculation is preliminary and the work is already underway, more data (the atmospheres of these almost assuredly rocky planets) will be needed before drawing any conclusions about water and life with confidence.

“The TRAPPIST-1 system provides one of the best opportunities in the next decade to study the atmospheres around Earth-size planets,” said Nikole Lewis, co-leader of the Hubble study.

To get answer of these tantalizing confusions, the astronomers plan to use NASA’s upcoming James Webb Space Telescope (JWST), which scheduled to launch in 2018. The James Webb Space Telescope will be the most powerful space telescope ever built, seeing cosmic objects with more precision than ever before. When it launches, the James Webb Space Telescope will sit at more than 1 million miles from Earth and will observe the Universe in the infrared (electromagnetic radiation). The Webb will search for gases that might be a by-product of life: chemical fingerprints of water, methane, oxygen, ozone.

Diagram showing how much stellar energy the TRAPPIST-1 planets receive, compared to worlds in our own solar system. Photo Courtesy:- Amanda Smith/IoA

Webb Space Telescope also will analyse planets’ temperatures and surface pressures (key factors in assessing their habitability) and other components of a planet’s atmosphere. Researchers say it should take five years to get a better idea of the composition and atmosphere of this sister solar system, and figure out whether water – and maybe life – are present. And when the European Space Organisation’s Extremely Large Telescope goes live in 2024, it should actually be able to detect water on the distant worlds from right here on Earth. However, James Webb Space Telescope doesn’t launch until next year.

According to the Verge, “Maybe it will tell us something about the frequency of life and habitable conditions in the Universe,” says Michael Gillon, lead study author and astronomer at the University of Liege in Belgium. “This system is really a cornerstone in exoplanetology.”



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