Tonight, look skyward for a “once in a blue moon” experience.
Stargazers can catch the “Blue Moon,” which last appeared in August 2012. The moon won’t actually have a blue hue; in astronomical terms a blue moon denotes the second full moon in a month with two full moons.
Blue moons are rare – they only happen once every two to three years -- so the saying “once in a blue moon” rings true.
A moon that actually appears blue is an even rarer sight. It can look blue when the atmosphere is filled with dust or smoke particles, like what happens after a dust storm, forest fire or volcanic eruption.
NASA explains more on the history of the "Blue Moon" in a video released this month.
In San Diego, the moon peaked early Friday -- at about 3:43 a.m --- and will appear again at 8:06 p.m.