Galaxies and Cosmology
Gamma-Ray Sky (October 28, 2009)
 This view of the universe shows the brightest sources of gamma rays, which are the most energetic form of radiation in the universe. Most of the activity is clustered along the plane of our home galaxy, the Milky Way (red band across the center). Individual objects include the Crab Nebula and a star system known as Geminga (far right edge), and a galaxy about 233 million light-years away known as NGC 1275 (at left, below the band of the Milky Way). Gamma rays are produced by some of the most powerful objects in the universe, including exploding stars and superhot disks of gas around black holes. This image was compiled by the space-based Fermi telescope. [NASA/DOE/Fermi]
» More Galaxies and Cosmology images in the Image Gallery
News & Features
What are astronomers latest estimates for the size and age of the universe? Follow the story from the pages of StarDate magazine
» Galaxy Guide: Discover spirals, ellipticals, and dwarfs.
» Balloon Astronomy Expands Our View Of The Universe (StarDate magazine)
Frequently Asked Questions
How big is our galaxy?
How many galaxies are there in the universe?
How many stars are in the Milky Way?
Is there a black hole at the center of the Milky Way?
What do galaxies look like?
What do scientists mean when they say space is curved?
What holds together the stars, planets, gases, and dust in a galaxy?
What is the difference between dark matter and dark energy?
What is the nearest galaxy?
What is the size and age of the universe?
What is the Sun's place in the Milky Way?
What is the universe made of?
When galaxies collide, do stars in one galaxy ever collide with stars in the other?
Keywords
Age of the Universe
Anatomy of Galaxies
Big Bang
Bubbles, Sheets and Voids
Chemistry of the Universe
Cosmic Background Radiation
Dark Energy
Dark Matter
Dark Matter and Dark Energy
Dwarf Galaxies
Elliptical Galaxies
Expansion of the Universe
Galaxies
Galaxy Clusters
Galaxy Formation and Mergers
Gamma-Ray Bursters
Giant Galaxies
Gravity
Hydrogen and Helium
Irregular Galaxies
Large and Small Magellanic Clouds
Local Group
Milky Way Galaxy
Origins of the Universe
Radio Galaxies
Relativity
Size of the Universe
Speed of Light
Spiral Galaxies
String Theory
Unified Theory
AstroGlossary Terms
Terms to learn or review include gravity waves, light-year, Olber's paradox, parsec, and red shift.
Links
SEDS Local Group Page
Galaxy Cluster Mug Shots
Spacetime Wrinkles
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