This Sunday at 7 a.m. ET, the moon will reach its annual perigee, its closest point to Earth for all of 2013. Thirty-two minutes after that, the moon will turn full. This celestial combination will bring about the biggest full moon of the year, a so-called supermoon.
This supermoon won’t be quite as super as the one we saw on March 19th, 2011, when the moon was only 221,565 miles from Earth, the closest it had been in 20 years. Sunday’s supermoon will be a bit more distant at 221,824 miles away. (That’s a difference of 259 miles, to save you the calculation.)
The supermoon of 2011 passed without apocalypse, but a few ships ended up stranded thanks to low tide and the moon’s particularly strong pull when close. This year’s supermoon will cause ocean tides to be higher and lower than usual.