WASHINGTON - Sky gazers across the Western Hemisphere are in for a treat when they look skyward on the final day of this month. For the first time in over a century, a Blue Moon, a Supermoon, and a Blood Moon will all coincide on the same day.
In the United States, you’ll have to be an early riser to see them, as all three will only coincide during the morning hours.
What exactly makes this event so special? Let’s break it down!
A full moon is not rare. They typically happen about once a month-- every 29.5 days to be specific. If a full moon falls in the first day or two of the month, a narrow window opens where there is the possibility of seeing another full moon at the end of that same month.
The second full moon of the month is known as a Blue Moon. Typically, a Blue Moon will appear once every three years or so. The last Blue Moon in the United States came in late July 2015. This year, we will be treated to two Blue Moons – something that won’t happen again until 2037. The first Blue Moon of 2018 will fall on January 31 and the second will come in late March.
What makes it a "Supermoon"
A Supermoon simply occurs when the moon is at its closest point to Earth (also known as perigee) while the moon is in its full phase. This has the effect of making the moon appear up 14 percent bigger and 30 percent brighter than a typical full moon. Similar to Blue Moons, a Supermoon tends to occur at regular intervals of about one every 14 months. Occasionally, there will be more than one in a single year.
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Photo credit: NASA/Bill Ingalls
There is some controversy here as to whether or not the moon on January 30 and 31 is actually a Supermoon because the moon will only be near full-- not 100 percent-- when it is at its closest point to earth. NASA has dubbed it close enough to permit labeling it as a Supermoon. The next true Supermoon will not occur until January 2019.
The Blood Moon
Finally, we have the Blood Moon. The name comes from the red and orange appearance that the moon takes on. This color change is caused by the Earth passing between the moon and the sun.
It is the light bending around the Earth due to gravity that passes through a portion of the atmosphere that causes the shift in color. This is known as a lunar eclipse. This is not to be confused with a solar eclipse, which is where the moon passes between the earth and the sun. The next lunar eclipse will happen in late July.
While these events are, in a sense, common in that they happen on a regular basis, all three happening at the same time is a much more rare occurrence. In the Western Hemisphere, this will be the first time all three have coincided since 1866, more than a century and a half ago.
When to see it
An issue some moon gazers in the eastern United States will have is that in order to see it in its full glory, you will have to be an early riser. The moon will rise at 4:40 p.m. on January 30 and remain in the sky all night, but it will not start to become eclipsed (the Blood Moon) until just after 6:45 a.m. on January 31. This leaves a narrow, half-hour window to see all three coincide before the moon sets at 7:15 a.m.
When the moon rises again at 5:51 p.m. that night, it will be full, but it will not be eclipsed.
Space enthusiasts, set your alarms for early next Wednesday morning if you want to see the big event! If you miss out, you won't get another opportunity again until December 2047.