Lunar Event of the Year!

January 30th, 2018 by Tavi Greiner

The news is everywhere! Tonight’s Full Moon is a special phenomenon, featuring three lunar events in one: a Perigee Full Moon, the second Full Moon of the month, and a Total Lunar Eclipse!

While tonight’s Full Moon may not look any more spectacular than usual – except for those who manage to see passing through Earth’s shadow – the coincidental combination of these three events makes it a moment not to be missed.

PERIGEE FULL MOON: Because the Moon’s orbit around the Earth is elliptical, there are closest and furthest points along the path. Perigee describes the closest point, and apogee relates the furthest point. A Perigee Full Moon (informally called a “Supermoon”) occurs when a Full Moon closely coincides with Luna’s closest orbital point.

A New Moon can also coincide with perigee, and both – Full and New Moons – often coincide with apogee (sometimes called a “Micromoon”.) Perigee Full Moons are not especially rare; they can occur a few times each year; but coinciding with other lunar events, such as the second Full Moon in a month or a Total Eclipse – is a less common occurrence. Coinciding with both is actually rare! You can learn more about Perigee and Apogee Moons, here.

SECOND FULL MOON of the MONTH: Typically, Full Moons occur once each month, or three times in each of the four astronomical seasons, but we occasionally see two Full Moons in one month, or four Full Moons in a particular astronomical season. Some people refer to this as a “Blue Moon”.

Two Full Moons in one month is not as common as Perigee Full Moons, but it is not a rare event; it happens roughly every fourteen months. This year, however, is a little special – we’ll see two months with two Full Moons (January and March) and one month with no Full Moon (February)! Of course, seeing this month’s second Full Moon coincide with both perigee and an eclipse adds aplomb to tonight’s event! You can learn more about “Blue Moons”, here.

TOTAL LUNAR ECLIPSE: A Total Lunar Eclipse occurs when the Full Moon passes directly through the deepest part of Earth’s shadow. This can only occur when the Sun, Earth, and Moon are perfectly aligned. Total Lunar Eclipses can occur a few times each year. They aren’t particularly rare events, but because they last only a few hours, witnessing them is highly dependent upon your location and your weather.

Seeing a Total Lunar Eclipse that coincides with both a perigee Full Moon and the month’s second Full phase is what makes this eclipse so special! The totality phase of tonight’s eclipse is a Pacific region event – Australia and east Asia will have spectacular views – but many other locations will be inline to see some of the partial phases. You can check a visibility map, here, and learn more about Total Lunar Eclipses, here.

VIEW the LUNAR ECLIPSE ONLINE: If you won’t be able to witness tonight’s eclipse (Totality begins just as the moon is sinking below the horizon in my region,) you can view the event from your computer or smartphone. There are several options listed below, but successful viewing for each of those locations will be dependent upon the regional weather.

*** NASATV  ***  Time and Date *** Virtual Telescope *** Griffith Observatory ***

If you learn of other live-streaming locations, note it in the comments or send us a tweet, and we’ll add them to the list! And if you capture any of your own images, please share them with us!


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3 Responses to “Lunar Event of the Year!”

  1. Rob Keown says:

    Very comprehensive review. Really enjoyed.

  2. Nick Evetts says:

    You mean Full Moon Perigee-Syzygy of the Earth-Moon-Sun system or Apogee-Syzygy of the Earth-Moon-Sun system, “Super Moon” like “Micro moon” is a Astrological term created by astrologer Richard Nolle in 1979, in Dell Horoscope magazine arbitrarily defined as:
    … a new or full moon which occurs with the Moon at or near (within 90% of) its closest approach to Earth in a given orbit (perigee). In short, Earth, Moon and Sun are all in a line, with Moon in its nearest approach to Earth. — Richard Nolle
    ( Astropro (No publication date; modified March 10, 2011). Retrieved 14 March 2011.
    Koren, Marina. “Astrologer Who Coined the Term ‘Supermoon’ Is ‘Delighted’ Everyone Uses It”. ( Atlantic. Retrieved 2018-01-30.
    So as Astronomers we should use Perigee-Syzygy of the Earth-Moon-Sun system or Apogee-Syzygy of the Earth-Moon-Sun system,

    • Tavi Greiner says:

      Thanks, Nick! I do believe that proper terms, like those you have noted – and as opposed to catchy phrases, like super and micro and blue and blood – are so much better at immediately illustrating the science behind what is happening!