The Universe: Stars
A star is a massive, luminous ball of gas that is held together by its own gravity. The nearest star to Earth is the Sun. A star begins as a collapsing cloud of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. Once the stellar core is sufficiently dense, some of the hydrogen is steadily converted into helium through the process of nuclear fusion. For most of its life, a star shines due to thermonuclear fusion in its core releasing energy that traverses the star's interior and then radiates into space. Almost all elements heavier than hydrogen and helium were created by fusion processes in stars.
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Polaris: As Pole Star
Introduction Two bright constellations occupy opposite sides of the pole star--the Big Dipper and Cassiopeia. As the celestial sphere rotates (or appears to rotate), these constellations also march...
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No Place to Hide: Missing Primitive Stars Outside Milky Way Uncovered
GARCHING, GERMANY (Feb. 18, 2010) – After years of successful concealment, the most primitive stars outside our Milky Way galaxy have finally been unmasked. New observations using ESO’s...
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NGC 281 Data Object Name: NGC 281, IC 0011, Pac Man Nebula, IC 1590 Object Type: Nebula, Star Cluster, Open Cl...
Stars form as gravitational forces coalesce the gas and dust in interstellar clouds until the material forms c...
Black Holes: What Are They? Black holes are the evolutionary endpoints of stars at least 10 to 15 times as mas...
Introduction Apparent magnitude is a measure of how much energy from a star reaches Earth. The term "magnitude...
Definition A supernova is the catastrophic self-destruction of a star. Left behind from this extremely energet...
Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. ...
Overview However tight his connections with the Almighty, the Jesuit priest Angelo Secchi couldn't have unders...
News Articles
Harvard-Smithsonian Center for Astrophysics (Oct. 12, 2009) Most stars form in clusters. Recent studies of...
European Southern Observatory (Aug. 25, 2009) Today ESO has released a new image of the Trifid Nebula, sho...
Harvard-Smithsonian Center for Astrophysics (Sep. 12, 2009) The Central Molecular Zone (CMZ) of our galaxy...
NASA-JPL (Sep. 24, 2009) Astronomers have witnessed odd behavior around a young star. Something, perhaps a...
NASA JPL, Pasadena, CA (Aug. 20, 2009) For decades, astronomers have gone about their business of studying...
European Southern Observatory, Garching, Germany (Aug. 21, 2009) New images released today by ESO delve in...
CAMBRIDGE, MA (April 7, 2010) Since Galileo first pointed a telescope at the sky 400 years ago, a myriad of t...
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The Milky Way galaxy contains several hundred billion stars of various ages, sizes and masses. A star forms wh...
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