page_title: Variable star
hierarchical_section_title: Variable star
caption_attribution_description: English: Compare the variable star Mira in the constellation of Cetus at two different times. Deutsch: Vergleiche den veränderlichen Stern Mira im Sternbild Cetus zu zwei verschiedenen Zeitpunkten.
context_page_description: A variable star is a star whose brightness as seen from Earth fluctuates.
  This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as either:
  Intrinsic variables, whose luminosity actually changes; for example, because the star periodically swells and shrinks.
  Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth; for example, because the star has an orbiting companion that sometimes eclipses it.
  Many, possibly most, stars have at least some variation in luminosity: the energy output of our Sun, for example, varies by about 0.1% over an 11-year solar cycle.
context_section_description: A variable star is a star whose brightness as seen from Earth (its apparent magnitude) fluctuates.
  This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as either:
  Intrinsic variables, whose luminosity actually changes; for example, because the star periodically swells and shrinks.
  Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth; for example, because the star has an orbiting companion that sometimes eclipses it.
  Many, possibly most, stars have at least some variation in luminosity: the energy output of our Sun, for example, varies by about 0.1% over an 11-year solar cycle.
caption: The variable star Mira at two different times
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