Hope for life beyond Earth

The discovery of seven planets with many characteristics similar to Earth in the same system has opened up new hopes for scientists searching for life beyond the blue planet.

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On February 22, NASA announced that it had discovered a star system just 39 light years away with seven planets that could potentially support life.

Why is this discovery important?

Speaking to Zing.vn, astronomy researcher Dang Vu Tuan Son, President of the Vietnam Young Astronomy Association, said that this is the first time scientists have discovered up to 7 planets the size of Earth in the same system.

In terms of location, three of the planets are in the habitable zone and the remaining four are also likely to have liquid water on their surfaces. Liquid water is a prerequisite for life.

The habitable zone is a limit of distance around stars that is just right, not too close and not too far away, so that if a planet is within that range, the temperature it receives from its parent star is enough for water to exist in liquid form on it.

For example, the Earth is in the habitable zone of the Sun, which is why it has oceans and life. If it were too close, the water would evaporate because of the heat, and if it were too far away, the water would freeze because there wasn’t enough heat. However, not all stars are like the Sun, so the limits of the habitable zone are different for each star.

In terms of structure, Mr. Son believes that these planets are similar to Earth in that they are all rocky planets, unlike the gas giants of the Solar System. Only planets with solid rocky surfaces have the opportunity for life to develop. Previously, scientists only knew of four rocky planets in the Solar System: Mercury, Venus, Earth, and Mars.

In addition, according to the Washington Post, scientists have long predicted that there are many planets in our Milky Way galaxy with characteristics similar to Earth. The new discovery shows that similar planets, which also have some potential for life, may be more common than previously imagined.

"Although up to now, all 7 of these planets as well as other potential extrasolar planets have not been officially confirmed to have liquid water, the discovery of this planetary system is also a remarkable thing for the search for celestial bodies that can allow life in the universe. Through that, we can look back at the formation and evolution of planetary systems, including the Solar System itself," said Mr. Son.

Simulation of the Trappist-1 planetary system with seven planets labeled b through h. Graphics: NASA/JPL-Caltech.

What happens next?

According to Mr. Son, although the recent discovery is important, these planets can only have liquid water, there has never been any definite confirmation about the possibility of life on these 7 planets.

Therefore, to know whether these planets can have life or not, scientists will need to make more measurements to determine their mass, size, orbit...

With planets as distant as the seven planets of the TRAPPIST-1 system, determining their exact composition and surface features is difficult, if not impossible.

Additionally, these planets may be tidally locked to their parent star, meaning they are close enough to their parent star to be gravitationalally influenced, close enough that their rotational period coincides with their orbital period, causing one side of the planet to always face the parent star (similar to how the Moon always faces the same side to Earth.

This makes these planets have no seasons, as half are always illuminated and half never receive sunlight. This in itself makes it more difficult for life to exist on these planets.

According to the Washington Post, scientists who discovered the TRAPPIST-1 planetary system are confident that this is the best target humanity has to study life beyond Earth. Exoplanet researchers (planets outside the Solar System) often pay attention to planets orbiting stars similar to the Sun.

However, because these stars are so bright, rocky planets appear as tiny dots that are difficult to see. The planets in the TRAPPIST-1 system are easier to see in the dim light of the white dwarf.

In the sky 39 light years away

Scientists also talked about the sky as seen from the newly discovered planets. The Washington Post reports that the central star of the newly discovered planetary system is called TRAPPIST-1, a dwarf star that is only one-tenth the size of the Sun and one-quarter the temperature.

However, the planets in the system are also much closer to TRAPPIST-1 than Earth is to the Sun. So from the surface of these planets, their central star would appear much larger than the Sun would appear from Earth.

Artist's impression of the star TRAPPIST-1 as seen from the planet TRAPPIST-1f. Photo: NASA.

In our wildest imagination, if one day humans could set foot on the surface of the outermost planet in our system (TRAPPIST-1h), we could stand there and watch the sky with the remaining 6 planets marching in turn. Each planet would be a black dot gliding past the huge pink star.

"Regardless of what secrets it holds, the TRAPPIST-1 planetary system will be a sight to behold," the Washington Post commented.

According to Zing