Check out the free view Saturday of a supermoon! Astronomers call it perigee-syzygy; the rest of us call it “supermoon.” Either way, the alignment of the sun and moon will coincide with the moon’s closest approach to Earth on Saturday (May 5), resulting in the biggest full moon of the year.
Saturday’s supermoon will be especially super. Richard Nolle, the astrologer who coined the term “supermoon,” defined it as a full moon that occurs within 12 hours of lunar perigee, or the point in the moon’s slightly non-circular monthly orbit when it swings closest to our planet. On Saturday, the timing of the two events will be almost perfect: the moon will reach its perigee distance of 221,802 miles (356,955 kilometers) — the closest lunar perigee of 2012, in fact — at 11:34 p.m. Eastern Time, and it will fall in line with the sun (thereby becoming full) just one minute later.
Under normal conditions, the moon is close enough to Earth to make its weighty presence felt: It causes the ebb and flow of the ocean tides. The moon’s gravity can even cause small but measureable ebbs and flows in the continents, called “land tides” or “solid Earth tides,” too. The tides are greatest during full and new moons, when the sun and moon are aligned either on the opposite or same sides of the Earth. (Photos: Mysterious Objects Spotted on the Moon)