DISCOVERING the most SUITABLE Alien Planet for Extraterrestrial Life | Space Documentary
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🌍 Is there an Earth-like
🌍 Is there an Earth-like planet in the universe? Like many people, you've probably already asked yourself this question. For several decades now, astronomers have been looking beyond the solar system and trying to find answers to this question in other star systems. K2-18 is one of the most interesting star systems for astrophysicists in search of extraterrestrial life.
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💥 K2 18b, the most promising exoplanet:
- The K2-18 star system is home to at least two exoplanets, K2-18 b and K2-18 c, which orbit the star K2-18. Both are more massive than the Earth: they are rocky superterrestrials, with a mass of 7 and 8.6 times that of the Earth.
The closest planet to the star K2-18 is K2-18 c. This hot super-Earth was discovered in 2017 and confirmed in 2018. It was in fact by studying K2-18 b, which had been discovered earlier in 2015 thanks to the American satellite Kepler, that the researchers spotted the signal of K2-18 c and were able to discover this exoplanet.
K2-18 b is indeed the one that interests astronomers the most. It is the most distant from the star K2-18. It is between 6 and 10 masses of the Earth and its radius is 2.3 times larger than that of our planet. It has an orbital period of 33 days and an equilibrium temperature of about -23°C, which is very close to the equilibrium temperature of the Earth of -18°C. As a reminder, the equilibrium temperature of a planet is the theoretical temperature of its surface in the absence of atmosphere. Astronomers believe that K2-18 b has all the characteristics to possess liquid water on its surface, which would make it habitable.
Its density, however, seems far too low for it to be a rocky planet. Either K2-18b is a rocky planet with liquid water on its surface, or it is a planet covered by a thick layer of ice. In other words, it is a rocky super-Earth surrounded by a small gaseous envelope or a gaseous mini-Neptune essentially composed of water and covered with ice. In any case, K2-18 b is made up largely of so-called volatile constituents, which form a fluid envelope, with elements like molecular hydrogen, helium or water. As often in the observation of the Universe, nothing is certain yet! These two hypotheses hold true and only the observations of the James Webb telescope can tell us more.
Indeed, the telescope is capable of analyzing the atmosphere of exoplanets, as it proved with the exoplanet Wasp 39-b. I remind you that James Webb has demonstrated the presence of CO2 in the atmosphere of Wasp 39-b, a hot gaseous planet located 700 light-years away in the Virgo Constellation. The principle is quite simple: when the exoplanet passes in front of its star, the light from the star will pass through its atmosphere. Scientists will then be able to study the spectrum of the light, in particular the absorption lines, which are sort of holes caused by the gases that the light has passed through before reaching us. Each gas has its own absorption lines. Just by studying the spectrum of light from K2-18 passing through the atmosphere of K2-18 b, astrophysicists will be able to determine which gases are present and in what proportions in the atmosphere of this exoplanet.
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🎬 On the program today:
- 00:00 - Introduction
- 01:04 - Journey from Earth to the K2-18 star system
- 02:40 - The Alpha Centauri star system
- 08:40 - The star Sirius
- 13:45 - Coconuts-2b, the closest exo planet photographed directly
- 16:46 - WD 0806-661 B, the coldest star in the Universe
- 20:32 - The solitary exoplanet PSO J318.5-22
- 23:52 - TOI-1452 b, the exoplanet ocean
- 28:31 - The K2-18 star system
- 29:26 - K2-18, the central star of the star system
- 30:50 - Red dwarfs
- 36:09 - The two exoplanets of the K2-18 star system
- 39:47 - How is the exoplanet K2-18 b the most promising for an extraterrestrial life form?
- 40:15 - The conditions for life to be possible on an exoplanet
- 43:15 - K2-18 b is located in the habitable zone of its star
- 44:49 - Water vapor discovered on K2-18 b
- 48:29 - Still some grey areas
- 52:15 - What would life be like on K2-18 b?
- 58:20 - What would life be like on an ocean planet?
- 01:03:23 - Could we communicate with the aliens of K2-18 b?
- 01:05:11 - So, is K2-18 b home to life?
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