exoplanets are planets that are outside the Solar system, in orbit of others stars, that is, they are part of other planetary systems. By 2019, the North American Space Agency (NASA) had already confirmed the existence of more than 4000exoplanets and from just over 3000 planetary systems.
Lookalso: 8 planets, 181 moons and 552,894 asteroids, know some numbers of the Solar System
How are exoplanets detected?
Since 2014, NASA has been carrying out an exoplanet exploration plan, however, observing them is not an easy task., since planets do not emit their own light and are much smaller than stars.
About 76,5% of exoplanets are observed when "passing in front" of a star. When this happens, there is a tiny reduction in the star's brightness. Transit time measurements of exoplanets allow you to estimate their distance from the star.
![Conceptual art of the Kepler spacecraft, responsible for most of the exoplanet discoveries. [1]](/f/681e7049debe68199ed67bb13c61073d.jpg)
About 19% of exoplanets are discovered because the stars that keep them in orbit wobble due to the
gravity their. This movementoscillatory makes their brightness suffer small deviations from frequency, for red and for blue, called red-shift and blue-shift, as with the sound waves, as a result of the Doppler effect.Around 2% of the discovered exoplanets were detected thanks to an effect relativistic called lensgravitational. when the light produced by a star passes close to some massive star, like a planet not too far away, it suffers small angular deviations in its trajectory, as when light passes through a lens.
At commentsdirect of exoplanets only occur under ideal conditions, however, about 1% of exoplanets was discovered by capturing imagesdirect. For that, several technologies are used in order to reduce the brightness of the stars that surround them, making it possible to capture a direct image of them.
During its first four years, the telescopeKepler concentrated the search for exoplanets on a small observation line 95 cm long. In that time, it focused on about 150,000 stars, luckily the optical device equipped in the telescope was able to detect thefirst Earth-like outer planet. At the time, the transit of this rocky planet, in front of its star, produced a 0.008% reduction in stellar brightness.
See too: Why did man never return to the moon?
Earth-like exoplanets
The first planet similar in size and mass to the Earth, located in the habitable zone of a star other than the Sun, was discovered in 2014 and named the Kepler-186f. THE habitable zone is the distance between the planet and your star, in which it is possible to exist Water in liquid state.
Supposedly, this is believed to be a condition for a planet to support life, at least life similar to ours. Despite the incredible discovery, the star in question was slightly different from the Sun, so this planet received less than a third of the sunlight that is radiated towards Earth.
![In the image we see the comparison between some known exoplanets and Earth. [2]](/f/365a1ff6ac8743631049816d1a2460c3.jpg)
By 2014, the Kepler mission had identified nearly 1000 exoplanets, one of them called the Kepler-22b, whose radius is about 2.4 times that of Earth, it was the first planet discovered to orbit the habitable zone of a star similar to the Sun.
Until the year 2019, it was known that only 161of the 4084 exoplanets discovered are solid, made of rock (these planets are called telluric), as is the Earth, the closest of which is at 12 light-years away from our planet, and the farthest away at 4443 light years.
Lookalso: Do you know what black holes are made of? Find out now!
According to astronomical observations, the number of stars in our galaxy is of the order of 1012 stars, something close to a few trillion sunsFurthermore, recent statistics indicate that for every star in our galaxy there must be at least one planet in orbit. This signals that there may be millions or even billions of planets similar to ours, orbiting other stars, waiting to be discovered.
Image credit
[1] Reproduction: Nasa
[2] Reproduction: Nasa
By Rafael Hellerbrock
Physics teacher
