In drawing done in 1844 by the astronomer looked a particular structure, so that it assumes the form of an exoskeleton of crab, crab in English, hence the name of the Crab Nebula, in fact, the nebula Crab. Actually, this question had already been cataloged by Charles Messier, who in 1758 looked at during a search session of comets, and the object was placed at the top of his list comet-looking object. Hence the name M1, that we still use to refer to this piece of light that is less bright in the horn of the constellation Taurus.
In fact, the substance of the first observation of M1 should be noted that the English John Bevis, the first man on the planet, this dim light, which employs about 6500 years to reach the Earth at a speed of 300,000 kilometers per second
A nebula between many of the sky, it seemed M1, classified simply as a planetary nebula, but in 1967 this object turned out to be one of the most interesting of the sky Lights. Previous studies had already revealed the high rate of expansion of the nebula, as well as anomalies in the spectrum of its central star. But it was revealed that in radio astronomy at the heart of M1 was a true monster of the sky. The young astronomy student, Jocelyn Bell identified a radio button, in fact, discovering the first pulsar (Pulsating stars), ie a neutron star, the story. It is because M1 is nothing more than the rest of the nucleus of a red supergiant star, left after the implosion / explosion of a supernova: a small star wreck, a few tens of km (28-30 km) in diameter that rotates at breakneck speed of one revolution every 33 milliseconds (About 30 turns on itself in a second!).
Reconstructing the rate of expansion of the nebula, and the rate of slowing of the pulsar, it was estimated that the star was visible in 1054 AD in the skies of Earth, as some chronicles graffiti and Indians (the star to the left of the moon in the picture) reported, and then became a star visibile ad occhio nudo di giorno, di magnitudine intorno ai -4,5 / -7 e cioè più luminosa di Venere, all'incirca come la Luna al primo quarto! La nebulosa allora altro non è che il "fumo" residuo di questa colossale esplosione, che si espande alla notevole velocità di 1500 km al secondo!
Questo oggetto è stato obiettivo di una sessione fotografica condotta da me assieme a Giovanni Cortecchia, in una serata con un cielo straordinariamente limpido, abbiamo effettuato una serie di scatti, utilizzando i filtri Rosso, Verde, Blu, OIII e Halfa ed anche se alla fine la messa a fuoco non è risultata perfetta, il risultato, grazie alla efficace elaborazione di Giovanni, non è niente male!
Nell'ingrandimento una freccia vi indica la pulsar, fa impressione pensare che quel puntino di luce, distante ben 6500 anni luce da noi sia una stella grande poco più di una montagna, e che ogni secondo compia 30 rotazioni inviandoci i suoi lampi intermittenti di luce!
