First of three summer 'Supermoons' to rise tonight

WASHINGTON, July 11 (UPI) -- Weather permitting, watchers of the night sky will be set aglow by a Supermoon this evening. A Supermoon is the same, regular moon, only it appears up to three-times bigger than normal.

Supermoons occur when the moon enters its full moon phase on the portion of its orbit when it swings closest to Earth's surface -- 30,000 miles closer.

Though the moon will appear much larger than usual, it has not actually swelled in size. Its impressive dimensions are a product of its slightly closer proximity and part optical illusion.

To take full advantage of the optical illusion part, it's best to catch a glimpse of the Supermoon when it's closest to the horizon -- peering out over the top of buildings and trees. The Supermoon can be seen in all its glory both Friday and Saturday night this weekend.

A Supermoon has many names. It can also be referred to as a Buck, Sturgeon or Corn Moon. Astronomer Bruce McClure said before that "we called them a perigee full moon ... Perigee just means 'near Earth.'"

If weather ruins your shot to see the Supermoon, the celestial phenomenon will return again on August 10 and September 9.