Super Moon

Definition: the phenomenon whereby the moon appears particularly large in the sky owing to the coincidence of its closest approach to the earth (the perigee) with a full (or new) moon.

A supermoon is a full moon or a new moon that approximately coincides with the closest distance that the Moon reaches to Earth in its elliptic orbit, resulting in a slightly larger-than-usual apparent size of the lunar disk as seen from Earth.

During a brief window of time—about five hours—the moon will cycle through several phases as it passes into and back out of perfect alignment with the Earth and sun. Viewers from eastern Asia through the Pacific to western North America will be in the moon’s path of totality. 

What is a Supermoon?

Blue Moon

Definition: a phenomenon whereby the moon appears bluish owing to smoke or dust particles in the atmosphere.

The reason the second definition of blue moon exists is down to an error originally made by amateur astronomer James Hugh Pruett (1886–1955). He misunderstood the basis for calculating the seasonal Blue Moon and wrote that a Blue Moon was the second Full Moon in a month in an article published in Sky & Telescope magazine in 1946. This erroneous definition since spread, particularly after it was quoted in a popular radio program called StarDate in 1980 and then appeared as an answer in a 1986 version of the board game Trivial Pursuit. Today, it is considered a second definition rather than a mistake.A Moon that actually looks blue, however, is a very rare sight. The Moon, full or any other phase, can appear blue when the atmosphere is filled with dust or smoke particles of a certain size; slightly wider than 0.7 micron. The particles scatter the red light, making the Moon appear blue. This is known as Mie scattering, and can happen for instance after a dust storm, a forest fire, or a volcanic eruption.

Eruptions like the ones on Mt. Krakatoa, in Indonesia (1883), El Chichon, Mexico (1983), on Mt. St. Helens (1980) and Mount Pinatubo (1991) are all known to have made the moon look blue. Some people even suggest that the term once in a Blue Moon is based on these rare occasions, rather than the Full Moon definitions.

BLUE MOON EXPLAINED

Blood Moon

                                               

Definition: the phenomenon whereby the moon in total eclipse appears reddish in color as it is illuminated by sunlight filtered and refracted by the earth's atmosphere.

A "blood moon" happens when Earth's moon is in full eclipse. While it has no special astronomical significance, the view in the sky is striking as the usually white-ish moon becomes red or ruddy-brown. The moon orbits around Earth, while Earth orbits around the sun. The moon takes about 27 days to orbit Earth and goes through regular phases in a 29.5-day cycle. The difference in these two cycles has to do with the relative positions of the sun, Earth and moon, which change during the moon's orbit.

 



NASA Explains