Space datavisualisation

Meteorite crashes

A meteorite is a celestial body that reaches the earth's crust. They should not be confused with asteroids or comets which do not reach the earth's crust.
They fall all over the Earth, but most of them fall on the Moon which is a natural shield against them. If it wasn't there, we wouldn't be here anymore for a long time. This is why there are so many craters on the Moon.
Meteorites, contrary to what one might think, are very beneficial for us. Indeed, according to some theories approved by a large majority of the scientific community, they are perhaps at the origin of life on Earth because they would have brought essential components for the appearance of life. The most telling example is that of water.
It is also quite rare that a meteorite dangerous to humans hits the Earth. It is estimated that once every 1000 years on average, a meteorite of about 100 m hits the Earth and that rises to 100 million years for a meteorite of about 10 km.

Picture of the day by NASA

ESO202-G23: Merging Galaxies

SO202-G23 is a colorful mess. It is a collision between two galaxies taking place over hundreds of millions of years. The representative colors give astronomers some idea of what is going on. Visible in this jumble is an active nucleus spewing ultraviolet radiation which lights up surrounding gas (blue); galactic arms contorted by the gravity of the collision (green); a star forming complex left of center (blue); and dust (red). In billions of years this mess might settle into a relatively normal looking galaxy.

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Hazardous Asteroid Orbits

A Near Earth Object (NEO) is any small body of the solar system whose orbit brings it closer to the Earth. If the orbit of a NEO crosses the Earth's orbit and the object measures more than 140 meters in diameter, it is considered as a potentially dangerous object. They are classified in 4 categories:
Atiras (IEO) have orbits strictly within the Earth's orbit: the aphelion distance of an Atira asteroid is less than the distance from the Earth's perihelion. The Apohele (APO) group of asteroids have a semi-major axis of less than 1 AU and cross the Earth orbit.
The Aton group (ATE) have a semi-major axis of more than 1 AU and cross the Earth orbit.
The Amors (AMO) have orbits strictly outside the Earth orbit: the distance to the perihelion of an Amor asteroid is greater than the distance to the aphelion of the Earth. Amor asteroids are also near-Earth objects, so q < 1.3 AU .

In astronomy, the absolute magnitude indicates the intrinsic brightness of a celestial object, in other words, the lower its magnitude, the larger its diameter. So the lower the magnitude, the more dangerous the celestial object is.
In conclusion the classification is based on two data, the magnitude (which indicates the diameter) and the distance from the Earth.