A supernova is visible phenomenon, directly from the cataclysmic explosion of a star that leads to its destruction and thus the death of the star.
This explosion is accompanied by massive increases its brightness as seen from Earth, which can last up to several weeks and even months.
It is visible in daylight and at night it can be as bright as the moon and even give a shadow to objects.
A supernova appears so often as a new star, hence its name, nova.
Supernovae are rare events in our Milky Way, about one to three per century, against the scale of the universe we observe every day.
It was during the supernova explosion the star releases the chemical elements, it was synthesized in its existence and during the explosion itself.
The shock wave from the supernova favors the formation of new stars, accelerating the contraction of regions of gas and dust in the interstellar medium.
The novas, unlike supernovae come from thermonuclear explosions, causing a partial destruction of the star by expelling part of its surface into interstellar space. Our sun will not end his life as a supernova but much quieter.
The death of a star can be mild or severe, depending on its mass. Below 1.4 times the mass of the Sun, the star goes out in peace, it will pass the size of a red giant (about 50 million km radius) to that of the Earth (about 6 000 km radius).
The star becomes a white dwarf. | | Between 1.4 and 5 times the mass of the Sun, his agony is much more violent. Its radius shrinks to 10 km The final density is enormous, the nuclei can not resist and the heart of the star becomes a giant nucleus of neutrons.
The collapse caused a terrible explosion, which will project the upper layers of the star into space and it will shine in the sky, a supernova.
Above 5 times the mass of the Sun, the collapse is extremely violent. It can not be stopped.
The heart of the star becomes a black hole.
The violence of the collapse produces a huge explosion, which projects the upper layers of the star into space.
As in the previous case a supernova will spread, hundreds of billions of miles, seeding the interstellar medium of heavy elements produced during the life of the star during the explosion.
These heavy elements are the building blocks of terrestrial planets like Earth.
This new Hubble image, is one of the most important images ever produced with an observatory in Earth orbit. It shows us a full and very detailed, the Crab Nebula. The Crab is arguably the most interesting subject, and also one of the most studied in the world of astronomy. The image of this nebula is the largest image ever taken with Hubble camera.
It was assembled from 24 individual exposures taken by the Hubble NASA / ESA Hubble Space. * List of the supernovae | | 
* The most famous supernova of the history of the astronomy. SN 1054 is a supernova the explosion of which was seen since the Earth from July 4th, 1054, called misty of the crab today which is situated in our galaxy in the constellation of the bull. |
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