On the evening of Tuesday, June 14th the Moon may look a bit larger and brighter than it typically does. This may not be obvious at a casual glance, but avid sky watchers will definitely notice the difference. On that night our satellite will come to within 222,000 miles, being at its closest distance or perigee. (For comparison, at its furthest point or apogee it lies nearly 253,000 miles from us.) Some, however, may be disappointed that this still doesn’t make the Moon “supersized” in appearance, as might be expected from the Supermoon term.
But there is something that will definitely change this disappointment into a “wow.” We have discussed the amazing “Moon Illusion” in past columns. As the Moon is rising (or setting), it often looks huge—but as it climbs higher into the sky, it begins to assume its usual appearance. The actual cause of this illusion is really unknown despite several theories. Whatever it is, the effect is at its dramatic best when we have a Supermoon Full Moon popping up over the horizon as we do this month!
There’s still more fun to be had connected with this event. One of the mysteries of this illusion is that if you look at the big rising Moon through a long cardboard tube such as paper towels are rolled on, the Moon immediately shrinks in apparent size! Alternately, turn your back to the Moon, bend over, and look at it between your legs. Again it shrinks! It would seem that what’s going on has something to do with perception in the eye-brain combination. But it’s anyone’s guess what that actually is. The remaining two Supermoons this year are in July and August, so if you are clouded out for June’s event you will have two more opportunities to experience it.
— James Mullaney
Former assistant editor at Sky & Telescope magazine & author of 10 books on stargazing. His latest, Celebrating the Universe!, is available from HayHouse.com.