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Blue Moon on 31 May Will Be a Mini Full Moon

The second full moon in May falls near the Moon’s apogee so instruments record a measurably smaller and dimmer full moon that the naked eye cannot easily detect.

Overview

  • The Moon will reach full for a second time in May on 31 May 2026 at about 10:45 MESZ after the month opened with a full moon on 1 May, creating a calendar‑month 'Blue Moon'.
  • That full phase coincides with the Moon’s approach to apogee, which timeanddate.de and planetarium sources place around 1 June when the distance is about 406,366 km from Earth.
  • Because the Moon will be near apogee this Blue Moon is classed as a Mini‑ or Micro‑full moon and will be measurably smaller and dimmer than average when recorded by instruments.
  • Astronomers say the size can be up to roughly 7 percent smaller and brightness about 15 percent lower than at average distance, but these changes are not noticeable to casual observers.
  • Blue Moons — the informal name for a second full moon in one calendar month — occur roughly every 2.5 years and the next similar dates are 2 December 2028 and 1 September 2031; related lunar events this year include a minivollmond on 30 June and supermoons at the end of 2026.