The word nebula is a catch-all term now used to describe different types of gas and dust clouds in interstellar space.
Emission nebulae, such as the Eagle Nebula, are vast, glowing clouds of ionised hydrogen and dust where stars are born. Others, such as planetary nebulae, are the bright shells of gas shed by dying stars. Despite their name, planetary nebulae have nothing to do with planets.
At one time galaxies such as Andromeda were referred to as nebulae until Edwin Hubble showed that they are separate galaxies and not gas clouds inside the Milky Way.
Image: Part of the Eagle Nebula (credit: The Hubble Heritage Team, STScI/AURA, ESA, NASA)
Astronomers Pete Lawrence and Paul Abel discuss the wonders to be found near a diagonal line of three stars in the constellation Orion known as Orion's Belt. The Horsehead Nebula is very difficult to see, even if you have a large telescope, but star cluster Collinder 70 can be seen with just a pair of binoculars.
Astronomers Pete Lawrence and Paul Abel discuss the Orion Nebula, a major sight found in a part of the constellation Orion known as the Sword of Orion. Also known as Messier 42 (M42), the Orion Nebula is an interstellar cloud of gas and dust just visible with the naked eye from Earth.
Sir Patrick Moore describes the Ring Nebula, also known as M57. The Ring Nebula is a planetary nebula.
Sir Patrick Moore and his guest Heather Couper discuss how stars get their start inside clouds of gas.
Sir Patrick Moore and Chris Lintott describe some of the beautiful sights in our galaxy, the Milky Way.
A nebula (from Latin: "cloud"; pl. nebulae or nebulæ, with ligature or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases. Originally, nebula was a general name for any extended astronomical object, including galaxies beyond the Milky Way (some examples of the older usage survive; for example, the Andromeda Galaxy was referred to as the Andromeda Nebula before galaxies were discovered by Edwin Hubble). Nebulae are often star-forming regions, such as in the Eagle Nebula. This nebula is depicted in one of NASA's most famous images, the "Pillars of Creation". In these regions the formations of gas, dust, and other materials "clump" together to form larger masses, which attract further matter, and eventually will become massive enough to form stars. The remaining materials are then believed to form planets, and other planetary system objects.
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