When the “Full Cold Moon” rises on Sunday night (Dec. 3) it will also mark the first (and last) “supermoon” of 2017.
Supermoons happen when a full moon approximately coincides with the moon’s perigee, or a point in its orbit at which it is closest to Earth. This makes the moon appear up to 14 percent larger and 30 percent brighter than usual. The moon becomes totally full at 10:47 a.m. EST (1547 GMT) on Sunday (Dec. 3). It will officially reach perigee less than 24 hours later on Monday (Dec. 4) at 3:45 a.m. EST (0845 GMT), when it is 222,135 miles (357,492 kilometers) away from Earth.
December’s supermoon is actually the first of three back-to-back supermoon full moons to come in the next two months. On Jan. 1 and Jan. 31, the full moon will also occur near the moon’s arrival at perigee, according to NASA, which billed the line up as a supermoon trilogy. The Jan. 31 supermoon is also the second full moon of January, making it a Blue Moon, and also occurs during a total lunar eclipse. – Space.com