An emission nebula is a cloud of ionized gas (i.e. a plasma) emitting light of various colors. The most common source for ionization are high-energy photons emitted from a nearby hot star. Among the several different types of emission nebula are H II regions, in which star formation is taking place and young, massive stars are the source of the ionising photons; and planetary nebulae, in which a dying star has thrown off its outer layers, with the exposed hot core then ionizing them. Cumulus of fair weather A cloud is a visible mass of condensed droplets or ice crystals suspended in the atmosphere above the surface of the Earth or another planetary body. ... A gas is one of the four main phases of matter (after solid and liquid, and followed by plasma), that subsequently appear as a solid material is subjected to increasingly higher temperatures. ... A Plasma lamp, illustrating some of the more complex phenomena of a plasma, including filamentation A solar coronal mass ejection blasts plasma throughout the solar system. ... ... In physics, the photon (from Greek φως, phōs, meaning light) is the quantum of the electromagnetic field; for instance, light. ... The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ... NGC 604, a giant H II region in the Triangulum Galaxy. ... NGC 6543, the Cats Eye Nebula A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. ...

Part of the Cone Emission Nebula is captured in this view from the Hubble Space Telescope.

Download high resolution version (701x711, 44 KB)The Cone Nebula. ... Download high resolution version (701x711, 44 KB)The Cone Nebula. ... Part of the Cone Emission Nebula is captured in this view from the Hubble Space Telescope. ... The Hubble Space Telescope (HST) is a telescope in orbit around the Earth. ...

General information

Usually, a young star will ionize part of the same cloud from which it was born. Only big, hot stars can release the amount of energy required to ionize a significant part of a cloud. Often, an entire cluster of young stars is doing the work. Globular Cluster M92 in the Hercules constellation. ...

The nebula's color depends on its chemical composition and amount of ionization. Due to the high prevalence of Hydrogen in interstellar gas, and its relative low energy requirement for ionization, many emission nebulae are red. If more energy is available, other elements can be ionized and green and blue nebulae are possible. By examining the spectra of nebulae, astronomers deduce their chemical content. Most emission nebulae are about 90% hydrogen, with the remainder helium, oxygen, nitrogen, and other elements. General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Legend: γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves: EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultrahigh frequency VHF = Very high frequency HF = High frequency... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ...

Some of the most beautiful emission nebulae visible from the northern hemisphere are the Lagoon Nebula and the Orion Nebula. Insert non-formatted text here The Northern Hemisphere is the half of a planets surface (or celestial sphere) that is north of the equator (the word hemisphere literally means half ball). On the Earth, the Northern Hemisphere contains most of the land and population. ... The Lagoon Nebula (also known as M8 and NGC 6523) is a giant interstellar cloud and H II region, in the constellation Sagittarius. ... The entire Orion Nebula in visible light Optical images reveal clouds of gas and dust in the Orion Nebula; an infrared image (right) reveals the new stars shining within. ...

Emission nebulae often have dark spots in them which result from clouds of dust which block the light. The combination of emission nebula and dust cloud make for some interesting looking objects, and many of these nebulae bear the name of objects that they resemble, such as the North America Nebula or the Cone Nebula. The distribution of ionized hydrogen (known by astronomers as H II (aitch two) from old spectroscopic terminology) in the parts of the Galactic interstellar medium visible from the Earths northern hemisphere (from the Wisconsin H-Alpha Mapper Survey) In astronomy, the interstellar medium (or ISM) is the matter and... Amateur astronomers photo of the North America Nebula The North America Nebula (also known as NGC 7000) is an emission nebula in the constellation Cygnus, close to Deneb (the tail of the swan and its brightest star). ... Part of the Cone Emission Nebula is captured in this view from the Hubble Space Telescope. ...

Some nebulae are made up of both reflection and emission components such as the Trifid Nebula. In astronomy, reflection nebulae are clouds of dust which are simply reflecting the light of a nearby star or stars. ... The Trifid Nebula (also known as M20 and NGC 6514) is an H II region at right ascension 18h 02. ...