Look up this weekend to see a big, bright “supermoon,’’ a full moon at its closest approach in 2013.
The moon orbits the Earth in an ellipse, meaning that its distance from the Earth varies. But about once every 14 months, the full moon coincides with the “perigee,’’ the closest approach the moon makes.
This year, the supermoon will occur Sunday, when the full moon sits just 221,823 miles from the Earth. It adds to a weekend of astronomical events, coming just days after the longest day of the year, the summer solstice, which takes place Friday.
Amanda Thompson, a planetarium presenter at the Museum of Science, said that the “supermoon’’ is a term that comes from astrology. The supermoon itself doesn’t hold much interest to scientists as an astronomical phenomenon — except as a reminder to take a look up and wonder at the night sky.
“The main reason we care about it is it encourages people to go out and look up at the moon,’’ Thompson said. “It’s something you take for granted every once in awhile.’’
The full moon will take place at 7:32 a.m. on Sunday morning, but Thompson said that people who step outside to take a look at the moon either night this weekend will get a good look at a full moon, up close. Although it may be difficult to tell that the moon looks any different, it may be as much as 30 percent brighter, and 14 percent larger than a typical full moon, Thompson said.
The closest supermoon of the century is still a couple of decades away, calculated to take place December 6, 2052. That day, the full moon will be 221,439 miles from Earth.