Discovery of 7 Earth-Like Planets Orbiting a Nearby Star Suggests Potential for Extraterrestrial Life

Just when astronomers thing they know where the most promising site for life beyond the solar system is, the place has gotten a whole lot better.

Looking at the stars with TRAPPIST, which is operated by a team of researchers of the ESO, astronomers located three planets orbiting a small, low-mass red dwarf star situated 39 light-year away. All the three planets are roughly terrestrial in size and sit in the habitable or the ‘Goldilocks Zone’ where temperatures may range from 0 to 100 deg C – perfect for water to remain liquid, and potentially hospitable for life.

The team coordinated by Michaël Gillon from the STAR Institute at the University of Liège in Belgium, readily directed other observatories to TRAPPIST-1, including NASA’s Spitzer Space Telescope and ESO’s Very Large Telescope. As it has appeared in Nature, TRAPPIST-1 consists of seven Earth-sized planets, out of which six could be rocky, and all seven potentially might have liquid water.

“All of these planets are the best targets found so far to search for signs of life in the next decade, and it is remarkable that they are all transiting the same star,” co-author and MIT planetary scientist Julien de Wit told Popular Mechanics in an email. “This means that the system will allow us to study each planet in great depth, providing for the first time a rich perspective on a different planetary system than ours.”

A Solar System That Looks Like Jupiter

Since it is a small-sized star, young, with a temperature of only 2,340 K, TRAPPIST-1 is classified as an ultracool dwarf. This inherent, weak star has been established to comprise only 8% of the mass of the sun; the estimated temperature of the star is about 2550K as opposed to 3800K for normal red dwarfs and 5800k for the sun. However, the system is a little less than twice the size of Jupiter, which is the case with TRAPPIST-1. Fortunately, the seven planets orbiting the TRAPPIST-1 are much closer to their star, and thus, to one another compared to the distances between planets in our solar system.

The inner planets revolve in circular Glycine orbits, much like Jupiter’s Galilean moons. All seven are at a much closer distance to TRAPPIST-1 than Mercury is to the sun and thus they get as much energy and heat as the Earth. The distance in the orbit is also relatively small, as the planets move around.

The space agency says: “If a man was standing somewhere on the surface of this planet he could look into the sky, and it could be that he could see geological formations or clouds of other planets, sometimes the neighbors can occupy almost the entire disc of the sky more than the moon in the sky of the Earth. ”

Of the available planets in the solar system some are more conducive for hosting liquid water than others. The star has been christened TRAPPIST-1A while the planets are TRAPPIST-1b, TRAPPIST-1c, TRAPPIST-1d, TRAPPIST-1e, TRAPPIST-1f, TRAPPIST-1g and TRAPPIST-1h in increasing order of their distance from the star. TRAPPIST-1b, 1c, and 1d require water to be too near and too hot.

However, TRAPPIST-1h may be too distant and cold for this to be true. However, TRAPPIST-1e, 1f and 1g are in the middle of the zone known as the Goldilocks Zone. Who knows, these might be true paradises with rolling waters and huge woods out there somebody, somewhere. Likely no, but it is not inconceivable. This is the case because we have very limited information on these planets, more so; the size estimate of these planets, their distance to the host star, and their orbital periods.

The exoplanets can be detected when they transit their host stars; this means, that from our vantage point, there is some portion of the star’s radiation that is being occulted by the exoplanet(s). It could then be possible to quantify the existence of planets and even their size, depending on the decline in the luminosity of the stars.

Red dwarfs like the TRAPPIST-1 represent the best kind of stars to look for as they are already small and therefore require no additional diminution to pick up variations in brightness. It is not also unusual for those planets that orbit dwarf stars to complete their orbits within weeks or days, thus there is ample opportunity for observing the motion across the disk. The TRAPPIST-1 planets have an orbital period ranging from 1. 5–20 days, that is, circumnavigate the star.

Red dwarfs are also the largest and enduring stars in the galaxy besides being the most common stars. Red dwarfs are believed to be the most abundant type of stars in the Milky Way galaxy where it is estimated that over ninety five percent are red dwarfs and there are a hundred billion stars in the galaxy.

It will take another 10 trillion years for the star TRAPPIST-1 to slowly burn the hydrogen, 700 times the age of the universe itself which will surely give life some chance to develop in the 7 planets that it hosts.

All these universes as interesting as they may sound have some attributes that raise question on its capability to support living beings. First, the planets are presumed to be synchronously rotating with TRAPPIST-1, meaning that one hemisphere of the planet is forever oriented toward the star, just like the near side of the Moon is eternally directed toward the Earth.

If this is so, one hemisphere of the planet is perpetually illuminated by sun while the other hemisphere is in darkness all the time. A third difficulty is the fact that red dwarfs can also be extremely active, which means that stellar eruptions, flares, and coronal mass ejections will occur with a vengeance and bombard any planets in the vicinity with radiation.

Therefore, it is critical to question the habitability of Proxima b, the nearest exoplanet to Earth, and so does a recent research. However, TRAPPIST-1 is less hotter than Proxima Centauri, so its planets may get less exposure of hard radiations. “As far as we know at the present time,” according to de Wit, “TRAPPIST-1 seems especially passive . ”Contrary to what its name may suggest, TRAPPIST-1 may be an actually benign star, conducive to life. However it is over 40 light-years away, is very small in angular size and is not very luminous as well.

How can we have been so sure in this?

Probing the Atmospheres of Exoplanets

Starshot Project is still in its early stages involving the launch of a fleet of microscopic spacecrafts called nanoprobes in the direction of the Alpha Centauri system, the closest stars to earth. They were able to use one laser, measuring tens of kilometers across on Earth, to boost a reflector plate to around 20% the speed of light by shining focused beams of light on the reflector, in quick succession. It is a technique that is called photonic propulsion and, using it, people can get to Alpha Centauri in 20 or 30 years. But we won’t be traveling to TRAPPIST-1 anytime soon.
For while scientists have since discovered additional planets in the same stellar system, this water world will remain out of reach for some time at least.

It is estimated to be about eight times more remote than our neighbouring star, Alpha Centauri. It is unimaginable to even try to send a probe at relativistic velocities because the round-trip distance is so large that it is highly likely that the probe would never get there even if it was launched tomorrow and it takes two years just to get to where it is going.

Even if it did, the idea that a light-year is equal to 5. 88 trillion miles, attempting to capture a signal from a small nanoprobe 40 light-years away, would be almost impossible. For now, this celestial hemisphere and its marvelous creation – the TRAPPIST system – will remain in the realm of home-school learning.

We will also see that there is much more we can do with our telescopes than you might have thought possible, including the JWST. By capturing a spectrum of light that passes through an atmosphere of the exoplanet and seeing what pieces are missing, or which electromagnetic wavelength is imaged by the planet’s atmosphere, it would also be possible to detect particular elements that the said atmosphere contains.

This technique known as absorption spectroscopy or remote spectroscopy can reveal what a planet’s atmosphere is made up of including one that is 40 light years away. In fohm of telescopes de Wit emphasizes that there is still a lot to be done with what we all ready have and what we are about to have!:“We used observations made by the Hubble telescope of this system in May, and thereby excluded the existence of large hydrogen-dominated atmospheres around the two inner planets and eliminated the possibility that they are ‘mini-Neptunes’ which would be uninhabitable; instead they are similar to the terrestrial planets Mercury, Venus, Earth and Mars”.

Data from the James Webb Space Telescope, which is scheduled to be launched next year, along with the completion of the Giant Magellan Telescope in Chile’s Atacama Desert, will allow us to make better discernments of these exoplanets than has hitherto been possible.

James Webb is equipped with 18 gold-plated mirrors and, due to that, it will be able to identify objects which are 16 times less luminous compared to the Hubble telescope; the GMT can be really massive with seven 15-ton mirrors and if so it may take images of exoplanets directly rather than searching for aberations in the star’s light.

These two, along with other telescopes such as the European Extremely Large Telescope, will determine precisely what these seven TRAPPIST-1 planets are made of and exactly what conditions each of their atmospheres has.

“Over the next two years, we are hoping to leverage Hubble’s capabilities to search for the presence of water- or methane-dominated atmospheres,” de Wit explains. “In the future, upcoming observatories like the James Webb Space Telescope will help us constrain the planets’ atmospheric composition, temperature, and pressure profiles—all essential information for determining the surface conditions possible over their globes.”

This material will not offer positive, direct evidence, however it could offer quite substantial photographic evidence should one of these planets support life. Astronomers will search for biosignatures like the abundance of oxygen in the atmosphere which can be as result of photosynthesis. Nonetheless, ample amounts of oxygen do not necessarily correspond with life being present. “We need more than just O2,” commented de Wit. “Deduced biosignatures may be in forms of such compound structures that include CFCs chlorofluorocarbons or a combination of structures including H2O, O2/O3, CO2 or CH4 structuring JWST cannot independently offer conclusive evidence for the existence of a biomass but will give us a guide to assess the habitability of planets. ”While sending a probe to the TRAPPIST-1 system is out of the question at the moment, it is actually nearby in terms of cosmos.

These planets orbit their sun in just few days and we will have hundreds of chances to study these exciting worlds with the help of latest enhancements of telescopes. In addition, according to many astronomers, TRAPPIST-1 might not be a unique case, but, for instance, one out of millions of similar red dwarfs and other stars our neighbors possessing vast planetary systems. At the same time, one can hardly doubt that there are lush extraterrestrial groves on one of the planets and we will find them, as science progresses further and further in this direction.

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