A nebula is a huge cloud of dust and gas, most of which is hydrogen gas, that occupies the space between galaxies.

Nebulae are commonly a breeding ground for stars that form from the gas. Nebulae like this are commonly known as stellar nurseries.

Other types of nebulae are:

• Planetary nebula, formed from gas ejected by a large exploding star
• Emission nebula, formed when ultraviolet light from a very hot star strips the electrons from hydrogen. The electrons then combine with protons to form more hydrogen and in the process emit red light
• Reflection nebula, that reflect the light, mostly blue, from nearby stars
• Ring nebula, formed in the shape of a ring

This is the Dumbell Nebula processed through filters to reveal the vivid red and green colours.

Credit:ESO

Some of the more well known nebula include:

• Crab Nebula in the constellation Taurus. This nebula was formed from the remains of a supernova, and exploding star, that was witnessed on Earth in 1054
• Eagle Nebula is a collection of giant columns of hydrogen gas in the constellation Serpens. The nebula is illuminated by ultraviolet light created by newborn stars
• Horsehead Nebula is in the constellation Orion. It is shaped like a horse's head and stands out because it is in from of an emission nebula that illuminates head's outline.
• Orion Nebula is near the constellation Orion. It is a huge gas cloud that forms a stellar nursery.