Astronomy and Space Professions: Astronaut

It is called “astronaut” in Europe and “cosmonaut” in Russia but these words mean the same thing. The job of astronaut is certainly the most dreaming of young people and many adults. It is also one of the riskiest trades in the world with that of submarine diver in extreme environment.

Because of these difficulties many astronauts are military pilots with a lot of experience, sometimes even test pilots.

The astronaut trade is open to all academics specializing in astronomy, applied physics, biology, medicine, and the amount of new science based on telecommunications and computing, to name only remote sensing.

Many astronauts are researchers in civil life who wrote to ESA or NASA to become an astronaut. After passing the entrance exams, they followed for a few years a physical training and advanced technical courses to know the astronautics and the mission that was going to be entrusted to them.

Then, in turn, they were lucky to be able to board a rocket or space shuttle to accomplish their mission. On their return some remain astronauts, others return to civilian life in their laboratory.


  1. John Wick Alexandria

    Visually, the quasars look like bluish stars a little blurry but unlike the stars, they are among the farthest objects in the universe. These are galaxies whose nucleus emits a lot of energy. Most quasars are hundreds of millions or even billions of light years away!

    On the thousands of cataloged quasars, two quasars are visible in a small telescope 20 cm in diameter: NGC 5128 Centaurus A of magnitude 7.6 and 3C273 in the constellation of the Virgin of magnitude 12.8. The latter photographed here on the left is more than 2 billion light-years away and to see it one would think that it is close to the Milky Way. You see it as it was here … 2 billion years ago, when life appeared on Earth! Today this quasar has no doubt disappeared.

    Despite being located very far in the universe, quasars are often as bright as 1000 galaxies! In fact astronomers believe that the quasars owe their intense energy and sometimes radioelectric energy to the activity of a huge black hole that would hide in their core. But how do we know that it would be a hole black since we do not see it?

    As a reminder, a black hole is a star that has collapsed on itself and is a few kilometers in diameter. But its attraction is so strong that it captures everything that passes near it, even 100 billion kilometers, including the stars. After billions of years, by capturing stars and gas, it can become gigantic and reach millions of kilometers in diameter.

    It is black and therefore invisible because it prevents even the light from leaving its surface. However, all the gas he captures wraps around him like a swirl, revealing his presence in space.

    Thus you can see below a galaxy (the gray part) in the center of which is a bright yellow-orange ring (on the right magnification). And the black hole, invisible and tiny on this scale, is right in the middle of the picture. It is he who has formed the ring and who is sucking all the material that it contains through the small bright swirl that you see in the center!

    The black hole is the only star that can create enough energy to explain the intense radiation of the quasars and other galaxies whose nucleus is very bright and very active.

    As we will see in the next chapter, in the future these black holes will grow and probably absorb all the stars and even all the galaxies in the universe.

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