Astronomy terms starting with A

17 terms

  1. Aberration With regards to physics, a discontinuity or distortion in an image produced by a lens.
  2. Absorption Spectra The spectra of electromagnetic radiation transmitted through a substance, with dark lines indicating the absorption of specific wavelengths.
  3. Accelerating Universe One where distance increase faster with time, in contradiction to those where the gravitational attraction of ordinary matter slows down the expansion.
  4. Acceleration The right of the lender to demand payment on the outstanding balance of a loan.
  5. Angular resolution The smallest angular size that the instrument can resolve.
  6. Angular Size The size of an object as viewed from the earth. For example, the moon subtends (covers) an angle of 1/2 of a degree.
  7. Anisotropy The difference in the property of a system with changes in direction. In this case, anisotropy refers to the difference in the temperature of the cosmic…
  8. Annihilated/annihilation A process in which a particle meets its corresponding antiparticle and both disappear.
  9. Anomaly Something that is out of the ordinary. For example if in a set of 1000 two winged, two legged, one headed, (essentially normal) chickens, one of them had…
  10. Antimatter Matter made up of elementary particles whose masses are identical to their normal-matter counterparts but whose other properties, such as electric charge…
  11. Antiparticle/antiquark/antielectron For most particle types there is another particle type that has exactly the same mass but the opposite value of all other charges.
  12. Apparent luminosities The brightness of an object as it appears from the earth. The apparent luminosity does not take into account the distance from the earth to the object…
  13. Atmospheric Imaging Assembly (AIA) an EUV Instrument onboard SDO.
  14. Atoms The smallest unit of matter that possesses chemical properties. All atoms have the same basic structure: a nucleus containing positively charged protons…
  15. Aurora A display of colored light in the atmosphere, caused by collisions between charged particles from a planet’s magnetosphere and atmospheric gases near…
  16. Auroral Oval The ring-shaped belts of auroral activity around the north and south magnetic poles.
  17. Auroral Substorms They are caused by streams of charged particles in the magnetotail that are accelerated to high energies and collide with atoms in the upper atmosphere…