Supermoons are making headlines, as the first of three visible in 2014 is scheduled to rise on July 12. There are technically five supermoons by definition in 2014, but only the full moons of July, August, and September will be visible. The other two happen during the new moon phase, when it is invisible on Earth.
The moon is a “supermoon” when it makes its closest approach to Earth, defined as perigee, in its elliptical orbit.
Saturday’s full moon, also known as the Buck Moon or Thunder Moon, reaches perigee (meaning “near earth”) at 222,611 miles away. This is about 30,000 miles closer than the moon at its farthest distance in 2014. However, Saturday’s supermoon won’t be the largest of the year. For that, you will have take a look on August 10, when the moon will be another 863 miles closer than Saturday.
If you’re feeling overwhelmed by the recent number of “supermoons” in the sky (and in your social media feeds), you’re not alone. Although they’ve always been around, these events have only been popularized within the past few years, likely enhanced by social media. As Bruce McClure writes at EarthSky.org:
To the best of our knowledge, astrologer Richard Nolle coined the term supermoon over 30 years ago. The term has only recently come into popular usage. Nolle has defined a supermoon as “a new or full moon which occurs with the moon at or near (within 90% of) its closest approach to Earth in a given orbit.”
Sky watchers might also be able to catch Mars and Saturn in their supermoon photos on Saturday:
Glare of upcoming supermoon shouldn’t wash out planets Mars and Saturn from evening sky. By Richard Joanne Escober. pic.twitter.com/naQ7JB2H84
— EarthSky (@earthskyscience) July 10, 2014
Of course, the best time to snap a photo is while the moon is rising or setting. The moon always appears larger at these times due to the Ponzo Illusion, in which the human mind judges the size of objects based on their surroundings or backgrounds. This optical illusion will far outweigh any additional size that might be gained with the closer proximity that the moon will hold on Saturday.
The largest supermoons happen approximately every 412 days, or every 14th full moon. Here is the 2014 supermoon Schedule:
Full moon of July 12 at 7:25 a.m. ET (11:25 UTC)
Full moon of August 10 at 2:09 p.m. ET (18:09 UTC)
Full moon of September 9 at 9:38 p.m. ET (1:38 UTC)