NEW SOLAR SYSTEM

Astronomers have recently identified a nearby solar system hosting seven Earth-sized planets. Most intriguing: Three planets that orbit its central star — known as TRAPPIST-1 — may even be within a habitable zone. That means they fall within a region that could support life as we know it.


As such, these newfound worlds are good sites to focus a search for alien life.


This dwarf star is only about the size of Jupiter.  It’s also much cooler than the sun. And it’s a relative neighbor to Earth, a mere 39 light-years away in the constellation Aquarius. Follow-up observations with the Spitzer Space Telescope and additional telescopes on the ground now show that what first had appeared to be a third planet is actually a quartet of Earth-sized ones. Three of these may be habitable.If those planets have Earth like atmospheres, their surfaces may even host oceans of liquid water.

The data also offer signs of a seventh, outermost planet.


How the new worlds were spotted
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‍All seven planets were detected by watching how their star dims as each passes — or transits — in front of it. Scientists measured how much of the star’s light each transit blocked from Earth’s view.

Knowing how big a planet would have to be to do that, the astronomer calculated that all seven must have roughly the same radius as Earth.Those dips in starlight also showed how fast the planets orbit their star: The innermost one makes a round trip in 1.5 Earth days. The outermost one takes roughly 20 days.

The planets’ masses range from about half to 1.5 times that of Earth. To figure that out, the researchers looked at the way the six inner planets tug on each other. The mass and size data then allowed the team to calculate the planets’ densities. All of this suggested that the inner six are rocky, as Earth is.

Question of existence of life
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Studying the atmospheres of such planets could reveal if they have life. One thing to look for: the gases methane and oxygen. Astronomers can look for those atmospheres (if they exist) with the Hubble Space Telescope or its successor, the James Webb Space Telescope. scientists have to be cautious, however, about how easy it will be to probe for details of planetary atmospheres. The light from ultra cool dwarf stars can vary. And it can be hard to understand how the planets’ atmospheres might behave.

Currently scientists have no idea what these planets look like. They could be wet or dry. But for the first time since the first exoplanet was discovered 25 years ago, they may be able to answer the question about life beyond our solar system.


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