Tonight is the first of six supermoons in 2015. It’s bit odd because we usually call some Full Moons “supermoons” but tonight is a New Moon. According to earthsky.org, the New Moons on January 20, February 18 and March 20 all qualify as supermoons. The Full Moons of July, August and September will get more attention because the brightness of a Full Moon does seem more spectacular.
The term supermoon is a pop astronomy creation used to call perigee New Moons or perigee Full Moons. Perigee means “near Earth.”
It was an astrologer, Richard Nolle, who gets credited with coining the term and his definition is “a new or full moon which occurs with the moon at or near (within 90% of) its closest approach to Earth.”
There is a matter of timing here. Tonight the Moon is “new” 13:14 UTC, but lunar perigee for this month doesn’t happen until tomorrow, January 21, at 20:06 UTC.
I don’t think you will be amazed looking at tonight’s Moon. Next month, the February New Moon will more closely coincide with lunar perigee, so it will be the closest new supermoon of the year.
Another oddity of the heavens will occur on March 20, 2015 when the supermoon causes a total eclipse of the equinox sun. I’ll mark my calendar.