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"Snow moon" 2019 will be this year's brightest "supermoon"

"Super blood wolf moon" to light up the sky

Another supermoon is set to grace the celestial stage Tuesday evening, and it's the largest and brightest our natural satellite will appear all year. 

We get a supermoon when the moon is full or nearly full and also at its closest point to Earth along its slightly elliptical orbit. This close approach is called perigee by astronomers. In 2019, there are three supermoons and they fall in the first three months of the year.

You may recall in January we had the spectacle of the "super blood wolf moon" in which a lunar eclipse or "blood moon" coincided with a supermoon and the first full moon of the calendar year, traditionally called the wolf moon.

Tuesday evening will bring the "super snow moon." Due to a number of nuances in the interactions between the sun, Earth and moon, the distance between us and and each supermoon varies a bit. It just so happens that this week's perigee will be about 362 miles closer to us than last month's supermoon, according to NASA.

Supermoon in Nobeoka, Japan
The full moon is seen in Nobeoka City, Miyazaki Prefecture on February 19, 2019; the phenomenon of "supermoon'' happens when the orb is at its closest point to Earth and looks larger than usual Katsumi Tanaka / AP

You'd need to have a remarkably trained eye to notice the difference between each supermoon. It's hard enough to even see the difference between a regular full moon and a supermoon, which only appears up to 14 percent larger in the sky and maybe 30 percent brighter.

If you really want to be wowed, your best bet is to check out the full moon when it rises in the east as the sun is setting in the west. This is when it will appear to be biggest, although this is mostly due to an optical illusion. 

This happens when the moon is close to the horizon and there are objects such as trees or buildings within our line of sight, NASA astronomer Mitzi Adams explains. "Because these relatively close objects are in front of the moon, our brain is tricked into thinking the moon is much closer to the objects that are in our line of sight," Adams says.

Adams adds that you can check the effect by holding a coin at arm's length so it covers the moon. Do this at moonrise when the moon appears huge on the horizon and later when it looks smaller high in the sky and you'll see that the same size coin covers the moon the whole night. 

It should be obvious why a February full moon is traditionally called a "snow moon" in the United States. The second calendar month is historically more filled with fluffy white precipitation than any other. 

This also means the super snow moon has a better chance of being blocked from view by, well ... snowfall. If that happens, there's still the third and final supermoon of 2019, which comes in exactly four weeks, on March 19.

This article first appeared in CNET

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