Equinox

• Means "equal night"
  • 12 hour day, 12 hour night
• Space and time when the plane of the Earth's equator passes through the geometric center of the Sun's disc
  • The moment the center of the visible Sun is directly above the Earth's equator
• Occurs twice a year
  • Vernal equinox
  • Autumnal equinox

Space Earth Astronomy