New NASA discovery: Star with seven Earth-like planets

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On the morning of 22 February NASA announced its latest space discovery: something very interesting and mysterious.

So what was NASA’s exciting news about the universe outside our solar system?

Astronomer Michael Gillon and his team have used NASA’s space telescope to recognise that seven Earth-sized planets are orbiting a star about 40 light years away, named Trappist-1. Three of these planets are in the habitable zone, where liquid water may be found on the surface. In fact, as they have the right atmospheric conditions, there could be water on any of these planets. Moreover, according to analysis of the composition of these planets to find their densities, astronomers have almost confirmed that one of the planets has a high possibility of holding a significant amount of liquid water.

Why has this caused such a sensation?

This is crucial for mankind because it is the first time we have found this many habitable planets around a single star, and the first time that we can measure the masses and radii of exoplanets relatively precisely. These seven planets, of all the Earth-like and habitable planets that have been discovered so far, are some of the most viable to follow up on. We can use telescopes, like the James Webb Space Telescope which will launch in 2018, to observe the atmosphere there, and even its bio-signature if present.

This discovery is a reminder that finding a second Earth is not just a matter of “if”, but “when”. Scientists believe that around every star there could be one or more planets. This suggests that there are many worlds out there that have a shot at being or becoming an habitable ecosystem for us to explore.

TRAPPIST-1 compared with our solar system and the Jovian moons

It sounds so familiar…

After reading all of this, you may think it sounds familiar. Don’t worry, you are right, because in May 2016 the Trappist-1 system was discovered to have Earth-like planets. However, that time NASA had only discovered three such planets, and none were in the habitable zone. This time another four have been added to the list, and three of them are habitable.

So how were they discovered?

To answer this question, we can look through the demonstration below, made by NASA.

When planets transit (pass in front of) a star, they dim it for a short period. After collecting lots of data, scientists can judge the radii, orbital periods and masses of transiting planets. We can see whether or not they are in the habitable zone by calculating their distances from the star from their orbital periods.

The planets are closer to Trappist-1 than the Earth is to the Sun, so it is because Trappist-1 is much cooler and smaller that they might still be habitable.

Another interesting point is that because all the planets are so close to their star, they are probably locked: they will always face the star with the same side, like the Moon does to Earth.

As scientists try harder and harder to find other planets with life, we should be optimistic about the future. Our generation might have the chance to live on Mars, why can’t we imagine life in the near future on these exoplanets?

Artist’s impression of the view on the surface of the exoplanet TRAPPIST-1f