Sky-watchers are gearing up for a super-sized moon that will grace evening skies this Sunday, October 16. The so-called hunter’s supermoon kicks off a lunar triple play happening over the next three months.
This month’s full moon is known in North America as the hunter’s moon. That’s because in other months, the moon rises about 50 minutes later each day, while the October moon rises just 30 minutes later. That offers more light overall during a 24-hour day, which came in handy for traditional hunters.
This month, the moon officially reaches its full phase at 12:23 a.m. ET (4:23 UT) on October 16, which means that the lunar disk will appear nearly equally full on the nights of both October 15 and 16.
This year, the hunter’s moon is also a supermoon.
Because its orbit around Earth is egg-shaped, there are times during the lunar cycle when the moon is at its shortest distance from Earth (called perigee) and times when the moon is at its farthest distance from Earth (called apogee).
Perigee does not always happen during a full moon, and because the size of the moon's orbit varies slightly, each month's perigee is not always the same distance from Earth. When a full moon coincides with lunar perigee, it's often dubbed a supermoon.
This month, the moon’s closest point to Earth will occur at 8 p.m. ET on October 16 (0:00 UT on October 17), when the full moon will be just 222,365 miles from our planet. The average distance between our two worlds is 238,855 miles.
Will we actually see a super-sized moon in the sky? The full moon on the 16th will appear 16 percent larger than average and nearly 30 percent larger than the year’s smallest full moon, which we saw back in April.
The effect should be detectable with nothing more than the naked eye. But practically speaking, unless you are a very keen lunar observer who diligently goes outside for every month’s full moon, it’s unlikely you will notice a measurable difference in size or brightness.
Even with the subtleties, the best time to catch this sky event is just after your local sunset on October 16, as the silvery orb rises in the east.
And if you miss this month’s supermoon, don’t despair. The full moons of November and December will also be supermoons. Next month’s supermoon promises to be the most impressive, as it will be the largest full moon visible in our skies so far this century.
Despite all the buzz surrounding supermoons and possible "super effects" on Earth, rest assured that there is no scientific evidence for any connection between a supermoon and natural disasters. It is, however, well known that tides are highest during new and full moons, which means if there is a storm surge during a new or full moon, unusually high coastal flooding may occur.
So, while supermoons may be more of a modern meme, like blood, blue, and black moons, the sight of that picturesque orb rising in the night sky is always worth a bit of sky-watching "lunacy."
Andrew Fazekas, the Night Sky Guy, is the author of Star Trek: The Official Guide to Our Universe and host of NG Live! ‘Mankind to Mars’ presentations. Follow him on Twitter, Facebook, and his website.