OBJECT	IMAGE Links to original sites	DESCRIPTION Oxford Dictionary of Astronomy	LINKS Links to informative sites
Moon		Earth's only natural satellite; The moon rotates such that it faces the Earth with the same face perpetually.	Named Lunar Formations Window to the Universe - Moon Inconstant Moon Virtual Reality Moon Phase Moon Phases Calendar NASA Moon Phases Animation Astro Moon Phases Animation
Stars		Luminous balls of gas in space; Nuclear fusion of Hydrogen to Helium; White Dwarf - hot, Red Giant - Cool; Sometimes Variable (varies in brightness) or Binary (2 stars bound by mutual gravity)	Stars Window to the Universe - Stars Livesky.com - Stars Visual Deep Sky - Variable Stars Star Myths Constellations & their Stars
Solar System		The collective name for the Sun and bodies that orbit it; 9 planets, 61 natural satellites, asteroids, comets, meteoroids.	Sun, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. Solar System Simulator NASA Planetary Photojournal Window to the Universe - Solar System Livesky.com - Planets 9 Planets
Open Clusters		Groups of stars formed together in the spiral arm of a galaxy.	APOD - Open Clusters SEDS - Open Clusters Visual Deep Sky - Open Clusters
Globular Clusters		Spherical groups of old stars in the halo of a galaxy; tens of thousands to millions of stars concentrated in the centre; 100-300 light years in diameter	Window to the Universe - Globular Clusters SEDS - Globular Clusters Visual Deep Sky - Globular Clusters
Diffuse Nebulae		Clouds of gas and dust in space - Emission: creates own light - Reflection: reflects light - Dark: absorbs light behind it	Web Nebula Window to the Universe - Nebulas Visual Deep Sky - Diffuse Nebulae
Planetary Nebulae		Bright cloud of glowing dust and gas surrounding a highly evolved star.	Planetary Nebula Observers Visual Deep Sky - Planetary Nebulae
Galaxies		A system of stars, often with interstellar gas and dust, bound together by gravity: The Earth is located in the outer spiral arm of the Milky Way galaxy.	NASA NSSDC Galaxies Window to the Universe - Galaxies The Galaxy Catalog Livesky.com - Galaxies Visual Deep Sky - Galaxies
Comets		A small body of ice and dust in orbit around the sun. The closer to the sun it comes, the larger the coma and tail, facing away from the sun.	Windows to the Universe - Comets Livesky.com - Comets SEDS - Comets Cometwatch Program Southern Comets JPL Comet Observation Home Page
Asteroids		Small rocky or metallic objects in the solar system mostly between Mars and Jupiter; Often called minor planets.	Windows to the Universe - Asteroids NASA NSSDC Asteroids Livesky.com-Asteroids Near Earth Objects
Meteors		A brief streak of light in Earth's upper atmosphere caused by the high speed entry of interplanetary debris: Meteorites hit the surface.	American Meteor Society Livesky.com - Meteors International Meteor Organisation Meteoritical Society
Constellations		88 areas of the celestial sphere made up of recogniseable groups of stars e.g. The Southern Cross, Orion, Taurus, Aquarius, Scorpius, Capricorn.	Windows to the Universe -Constellations Livesky.com - Constellations Star Myths Constellations & their Stars
Artificial Satellites		Space craft in orbit around the Earth; e.g. International Space Station, Hubble Space Telescope, Communications Satellites etc.	NASA Human Space Flight Heavens Above Livesky.com - Satellites Liftoff J-track Satellite tracker

All: THE ELECTRONIC SKY

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Catalogues

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Messier

MESSIER CATALOGUE

NGC/IC

NGC/IC Project