Space & Time Articles

• Astrophysics
  Dark Matter
  Cosmology
  Astronomy
  Big Bang
  Black Holes
   
  

  Dark energy

  In physical cosmology, dark energy is a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe. Assuming the existence of dark energy is ... > more
• Galaxies
  Stars
  Eris (Xena)
  Astronomy
  Astrophysics
  Kuiper Belt
   
  

  Local Group

  The Local Group (also called M31 group or the Andromeda group) is the group of galaxies that includes our galaxy, the Milky Way. The group comprises over 30 galaxies, with its gravitational center ... > more
• Asteroids, Comets and Meteors
  Solar System
  Astronomy
  Pluto
  Satellites
  Solar Flare
   

  Near-Earth asteroid

  Near-Earth asteroids (NEAs) are asteroids whose orbits are close to Earth's orbit. Some NEAs' orbits intersect Earth's so they pose a collision danger. On the other hand, NEAs are most easily ... > more
• Galaxies
  Astrophysics
  Astronomy
  Stars
  NASA
  Space Telescopes
   
  

  Galaxy

  A galaxy is a massive, gravitationally bound system consisting of stars, an interstellar medium of gas and dust, and dark matter. Typical galaxies range from dwarfs with as few as ten million stars ... > more
• Cosmology
  Cosmic Rays
  Astrophysics
  Big Bang
  Astronomy
  Black Holes
   
  

  Cosmic microwave background radiation

  In cosmology, the cosmic microwave background radiation is a form of electromagnetic radiation discovered in 1965 that fills the entire universe. It has a thermal 2.725 kelvin black body spectrum ... > more
• Space Telescopes
  Space Exploration
  NASA
  Satellites
  Astronomy
  Cosmic Rays
   
  

  Telescope

  A telescope is an instrument designed for the observation of remote objects. The term usually refers to optical telescopes, but there are telescopes for most of the spectrum of electromagnetic ... > more
• Pluto
  Kuiper Belt
  Extrasolar Planets
  Solar System
  Eris (Xena)
  Astronomy
   
  

  Definition of planet

  The definition of "planet" has for some time been the subject of intense debate. Although the word dates back thousands of years, no officially decreed scientific definition of "planet" existed ... > more
• Pluto
  Solar System
  Kuiper Belt
  Astronomy
  NASA
  Space Exploration
   
  

  Ceres (dwarf planet)

  Ceres, also designated 1 Ceres or (1) Ceres, is the smallest dwarf planet in the Solar System and the only one located in the main asteroid belt. With a diameter of about 950 km, Ceres is by far the ... > more
• Black Holes
  Astronomy
  Astrophysics
  Galaxies
  Stars
  Solar Flare
   
  

  Black hole

  A black hole is a concentration of mass great enough that the force of gravity prevents anything from escaping it except through quantum tunnelling behaviour (known as Hawking Radiation). The ... > more
• Astrophysics
  Stars
  Cosmology
  Black Holes
  Cosmic Rays
  Solar Flare
   
  

  Stellar nucleosynthesis

  Stellar nucleosynthesis is the collective term for the nuclear reactions taking place in stars to build the nuclei of the heavier elements. The processes involved began to be understood early in the ... > more

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