Glossary and Acronyms
Background radiation (cosmic)—
The radiation left over from the Big Bang explosion at the beginning of the universe. As the universe expanded, the temperature of the fireball cooled to its present level of 2.7 degrees above absolute zero.
A star-like object that contains less than about 0.08 the mass of the Sun and is thus too small to ignite nuclear fuels and become a normal star. Brown dwarfs emit small amounts of infrared radiation due to the slow release of gravitational energy.
An as yet unknown form of energy that pervades the universe. Its presence was inferred from the discovery that the expansion of the universe is accelerating, and these observations suggest that about 70 percent of the total density of matter plus energy is in this form. One explanation for dark energy is Einstein’s cosmological constant.
Cosmological concept that states that the universe will expand forever at a decelerating rate, and will never pass an outer limit.
A sudden burst of gamma rays coming from a source usually in deep space. The burst may last from a fraction of a second to several minutes.
Gravitational lensing due to a stellar mass object. This lensing phenomenon is termed “microlensing” because the mass of the lens is so small compared with that of a galaxy.
Microlensing of distant stars by intervening faint stars can reveal planets in orbit around the lensing star.
The main technique used by astronomers to map sources at high resolution and to measure their positions with high precision.
Kuiper Belt objects (KBOs)—
Icy planetesimals distributed in a roughly circular disk in the outer regions of our solar system, 50 to 100 AU from the Sun.
Radiation from an approaching object is shifted to higher frequencies (to the blue), while radiation from a receding object is shifted to lower frequencies (to the red). A similar effect raises the pitch of an ambulance siren as it approaches. The expansion of the universe makes objects recede so that the light from distant galaxies is redshifted. The redshift is often denoted by z, where z=v/c and v is the velocity and c the speed of light.
Astronomy and Astrophysics Planning Board
NRC Astronomy and Astrophysics Survey Committee
Advisory Committee for AST (NSF Astronomical Sciences Division)
AURA Coordinating Council of Observatory Research Directors
Atacama Large Millimeter Array
Advanced Radio Interferometry between Space and Earth
Advanced Solar Telescope (now called the Advanced Technology Solar Telescope, or ATST); NSF Astronomical Sciences Division
NSF Division of Atmospheric Sciences
Associated Universities for Research in Astronomy, Inc.
NRC Committee on Astronomy and Astrophysics
Combined Array for Research in Millimeter-wave Astronomy
Compton Gamma-Ray Observatory
Committee on the Organization and Management of Research in Astronomy and Astrophysics
U.S. Department of Energy
Expanded Very Large Array
Energetic X-ray Imaging Survey Telescope
Frequency Agile Solar Radio telescope
Green Bank Telescope (now named after Senator Robert C. Byrd)
Gamma-ray Large Area Space Telescope
Giant Segmented Mirror Telescope
DOE Office of High Energy and Nuclear Physics
DOE Division of High Energy Physics
High Energy Physics Advisory Panel
Hubble Space Telescope
Laser Interferometer Gravitational-Wave Observatory
Laser Interferometer Space Antenna
Large-aperture Synoptic Survey Telescope
NSF Mathematical and Physical Sciences Directorate
MPS Advisory Committee
NSF Major Research Equipment line
National Aeronautics and Space Administration
Next Generation Space Telescope
National Optical Astronomy Observatory
National Radio Astronomy Observatory
National Research Council
Naval Research Laboratory
Nuclear Science Advisory Committee
National Science Foundation
National Solar Observatory
National Virtual Observatory
NSF Office of Multidisciplinary Affairs
Office of Management and Budget
NSF Office of Polar Programs
NASA Office of Space Science
Office of Science and Technology Policy
Robotic Optical Transient Search Experiment
Single Aperture Far Infrared observatory
Science Assessment Group for Experiments in Non-Accelerator Physics
Solar Dynamics Observatory
Square Kilometer Array
South Pole Submillimeter-wave Telescope