Nebula

A nebula is an interstellar cloud of dust, hydrogen gas, helium gas and plasma. Nebulae often form star-forming regions. In these regions the formations of gas, dust and other materials clump together to form larger masses, which attract additional matter, and eventually will become big enough to form stars. The remaining materials are then believed to form planets.

The Crab Nebula is a supernova remnant and pulsar wind nebula in the constellation of Taurus. The nebula was first observed by John Bevis, and corresponds to a bright supernova recorded by Chinese and Arab astronomers in 1054. At the center of the nebula lies the Crab Pulsar, a rotating neutron star, which emits pulses of radiation from gamma rays to radio waves with a spin rate of 30.2 times per second. This nebula was the first astronomical object identified with a historical supernova explosion.

The Orion Nebula, also known as Messier 42, is a diffuse nebula situated south of Orion's Belt. It is one of the brightest nebulae, and is visible to the naked eye in the night sky. M42 is located at a distance of 1,270±76 light years and is the closest region of massive star formation to Earth. The M42 nebula is estimated to be 24 light years across.