When it comes to the question of habitable celestial bodies, Earth is still the galactic ultimate. We know of no other planet that offers its potential inhabitants such a life-friendly environment.
This is why the search for celestial objects that could be home to extraterrestrial life forms due to their spatial position and natural composition has always been one of the central points of modern space research. Research Source
The Kepler space telescope, which took a close look at our galactic neighborhood between 2009 and 2018, also pursued this goal, and as we now know, the instrument named after the German Astronomer Johann Kepler was to achieve some breathtaking successes during its mission.
Which celestial bodies were added to the star maps with the help of Kepler, and which of these exoplanets could challenge Earth's rank as the most flourishing haven?
The Kepler Space Telescope:
On March 7th, 2009, NASA's Kepler space telescope began its galactic service as the 600 million dollar one-ton plus a piece of equipment was launched from its booster rocket toward space.
Terrestrial experts gazed spellbound at those milestones that could be recorded with the help of the complex telescope.
Specifically, Kepler was to direct their gaze to a fixed section of the constellation Swan. However, it was not the approximately 190 000 stars contained therein that were the main focus of this mission but the search for previously unknown exoplanets.
As a reminder Exoplanets are planetary celestial bodies that are not gravitationally bound to our sun but to another star to erase the white spots from the star maps.
The space telescope employed the transit method, which examines the changing brightness ratios of stars as soon as a planet passes in front of its host star as seen from Earth; the brightness of the corresponding parent star is also temporarily reduced as a result of the observation of these recurring brightness curves.
It is possible to deduce not only the existence of a transiting planet, but also important information about the celestial body's orbital period, planetary radius, and orbital inclination. investigations that analyze the radiation according to certain criteria also provide information about the composition of the atmosphere, the temperatures, and the reflectivity of the exoplanet.
In particular, the particular objective of the Kepler mission was to discover relatively small and therefore potentially habitable exoplanets. In the same breath, the space telescope also provided important data on variable stars.
These celestial objects exhibit quite short-term variations in brightness, the causes of which are not known. The original mission period, which initially spanned three and a half years, would eventually be extended to October 30th, 2018.
After two reaction wheels failed in May 2013, the space telescope's observation method had to be modified. It did not take long before the large-scale project bore its first galactic fruits. In January 2010, the discovery of the first five planets located by Kepler was announced.
Over time, many more previously unknown celestial bodies were to be added to the star maps. Let's now take a look together at the most important discoveries of the space telescope
Kepler 62:
Kepler-62 is about 1200 light-years away from our blue home planet. We know that the object in the constellation Lyra is slightly colder than our sun and is orbited by at least five exoplanets at the same time. Research Source
Especially the two outer planets, Kepler-62e and Kepler-62f, located in the habitable zone, arouse the special interest of terrestrial researchers. Some indications point to the fact that they are rocky planets.
which could accommodate water in durable liquid form. Some experts go so far in their remarks that they even suppose that the two celestial bodies represent so-called ocean planets, as the name alone reveals that this is a hypothetical planet form whose surface is completely covered by water. However, the Kepler-62 planetary system is not the only association of alien celestial bodies that could be discovered with the help of the space telescope.
Kepler-90:
In October 2013, officials announced the discovery of the Kepler-90 planetary system. The namesake host star is a main-sequence star 2800 light-years away from us that, to our current knowledge, is slightly larger and more luminous than our sun. We know that at least eight planets revolve around Kepler-90. Research Source
Thus, this galactic grouping is the only known system that includes as many planets as our home solar system. The data collected so far suggests that the six inner planets may be mini-Neptunes or compact super-earths.
The two outermost planets, in turn, are classified as gas giants. The spatial constellation of the individual celestial bodies shows that the corresponding planets are much more densely packed together than is the case in our solar system.
The orbit of the outermost Kepler-90 planet roughly corresponds to the orbit of our blue home planet around the sun, while the first planets within this system were all located in 2013. Kepler-90i, the last known planetary celestial body to date, followed in 2017.
Kepler-186f:
If we traveled 490 light-years from our planet into the constellation of the swan, we would come across the exoplanet Kepler-186f, which has striking similarities to our planet in terms of the dimensions of the celestial body that orbits the red dwarf Kepler-186. Research source
Consequently, experts assume that the planet is only slightly larger than our earthly home. Consequently, it's also obvious that it's not a gas planet but an earth-like celestial body with a solid surface.
Its central star orbits Kepler-186f at a distance of about 31 million miles, which means that the exoplanet needs about 130 days for a complete revolution, although the celestial body is much closer to its host star than the earth is to the sun.
This does not mean that Kepler-186f does not have favorable conditions for life. Specifically, the red dwarf Kepler-186 has a much lower radiant power than our sun, which means that the exoplanet is located at the outer edge of the habitable zone.
Assuming a suitable atmospheric greenhouse effect, temperatures could prevail on Kepler-186f, which would allow the existence of water in a permanently liquid form. Furthermore, it's assumed that the celestial body has a stable climate and passes through regular seasons.
k2-18b:
In the context of the investigation of the extrasolar planet k218b, researchers registered a much-noticed galactic milestone: for the first time, terrestrial experts were able to detect water vapor in the atmosphere of an exoplanet. k218b was originally discovered in 2015 with the help of the Kepler space telescope. Research Source
The Hubble space telescope would deliver ground-breaking data indicating the existence of atmospheric water vapor. later, the celestial body is located about 110 light-years from our blue home planet, orbiting a dwarf star in the constellation Leo.
Since k2 18b is also located in the habitable zone of its native system, it's the first known exoplanet in history that demonstrably fulfills both basic requirements for the possible formation of life: the appropriate temperatures as well as the existence of water.
The researchers said that the planet is probably composed of silicates and ice, although the existence of liquid water on the surface of the celestial body has not yet been proven. Many experts think that the chances are quite favorable.
If this is true, it is theoretically possible that the first organisms have already formed on k218b. However, to test this assumption for its scientific validity, the exoplanet, which is twice the size of Earth and eight times its mass, must be studied in more detail.
Kepler-1649c:
According to Jeff Coughlin, director of the Seti Institute's K2 Science Office, Kepler-1649c is the most Earth-like exoplanet ever found, but what moved the member of that organization, whose mission is to search for intelligent extraterrestrial life, to make this bold statement? Research Source
Is it certain that the celestial body was discovered only after Kepler had already stopped its service? The new sighting of the captured Kepler images confirmed the existence of the fascinating exoplanet. Kepler-1649c is classified as a rocky planet with a radius of 1.06 times that of our Earth.
Furthermore, the celestial body orbits its host star, a red dwarf within the habitable zone, in just 19.5 days. Is there a planet that particularly fascinates you? Just drop your thoughts.