ESA Articles

• Stars
  Galaxies
  Astronomy
  Astrophysics
  Nebulae
  Black Holes
   
  

  Star cluster

  Star clusters are groups of stars which are gravitationally bound. Two distinct types of star cluster can be distinguished: globular clusters are tight groups of hundreds of thousands of very old ... > more
• Physics
  Engineering
  Chemistry
  Sports Science
  Forensic Research
  Civil Engineering
   
  

  Science

  Science, in the broadest sense, refers to any systematic knowledge or practice. In a more restricted sense, science refers to a system of acquiring knowledge based on the scientific method, as well ... > more
• Stars
  Jupiter
  Sun
  Extrasolar Planets
  Astronomy
  Solar Flare
   
  

  Red supergiant

  Red supergiants are supergiant stars of spectral type K-M and a luminosity class of I. They are the largest stars in the universe in terms of physical size, although they are not the most massive. ... > more
• Space Probes
  Space Exploration
  Space Station
  Astrophysics
  Solar Flare
  Astronomy
   
  

  Rocket engine

  A rocket engine is a reaction engine that can be used for spacecraft propulsion as well as terrestrial uses, such as missiles. Rocket engines take their reaction mass from within the vehicle and form ... > more
• Cosmology
  Big Bang
  Astrophysics
  Black Holes
  Space Telescopes
  Astronomy
   
  

  Multiverse

  A multiverse (or meta-universe) is the hypothetical set of multiple possible universes, including our universe, which comprise the absolute whole of physical ... > more
• Space Probes
  Space Exploration
  Space Station
  Astronomy
  NASA
  Space Missions
   
  

  Spacecraft propulsion

  Spacecraft propulsion is used to change the velocity of spacecraft and artificial satellites, or in short, to provide delta-v. There are many different methods. Each method has drawbacks and ... > more
• Astronomy
  Galaxies
  Cosmic Rays
  Black Holes
  Solar Flare
  Stars
   
  

  Light-year

  A light-year or lightyear (symbol: ly) is a unit of measurement of length, specifically the distance light travels in a vacuum in one year. While there is no authoritative decision on which year is ... > more
• Cosmology
  Big Bang
  Astrophysics
  Cosmic Rays
  Black Holes
  Dark Matter
   
  

  Big Bang nucleosynthesis

  In physical cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, ... > more
• Black Holes
  Astronomy
  Astrophysics
  Space Telescopes
  Galaxies
  Space Exploration
   
  

  Quasar

  A quasar is an astronomical source of electromagnetic energy, including light, which shows a very high redshift. The scientific consensus is that this high redshift is the result of Hubble's law. ... > more
• Space Probes
  Aviation
  Vehicles
  Space Exploration
  Space Station
  Sports Science
   
  

  Rocket

  The traditional definition of a rocket is a vehicle, missile or aircraft which obtains thrust by the reaction to the ejection of fast moving fluid from within a rocket engine. There are many ... > more

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