Grab your coat and head outside this evening, as the night sky is set to put on an extra special show—the Hunter's supermoon and Comet Tsuchinshan-ATLAS, also known as C/2023 A3 or simply Comet A3, are both visible for viewers in the northern hemisphere.
You can catch both celestial events early in the evening, so no need to stay up late.
Comet A3 has been capturing headlines all week and will gradually get dimmer as the week progresses. The next time this comet will pay us a visit is in 80,000 years, so missing it isn't an option.
Thankfully, supermoons are a bit more common—Wednesday's moon is the third in a series of four occurring this year. This supermoon is extra special, however, as it will be the biggest and brightest of the series.
Comet Tsuchinshan-Atlas makes an appearance in the western night sky near the Dry Creek Trailhead in Boise, Idaho on October 14, 2024. Both the comet and a near-full supermoon will be visible across the U.S. tonight. Kyle Green/AP
When Is the Next Supermoon?
The next full supermoon will occur on Thursday, October 17. The moon will technically reach its fullest at 7:26 a.m. ET, but will appear full from Wednesday until Friday. The next supermoon in the series of four is just a month later, on November 15.
Tonight, the moon will rise at 5:46 p.m. ET and will set at around 7:15 a.m. Thursday morning local time on the East and West Coast.
How Often Does a Supermoon Occur?
According to NASA, supermoons happen three or four times a year.
You'd be forgiven for thinking supermoons aren't so super after the succession of them that have graced the skies these past few months. But that's just how they come—consecutively.
Supermoons occur consecutively because the moon's elliptical orbit around Earth remains roughly fixed as both the Earth and moon revolve around the sun. However, the orbit's orientation lags slightly due to the sun's gravitational influence, causing the moon's perigee (closest point to Earth) to shift.
It takes about 411 days for the Moon's perigee to align with the same position relative to the sun, creating a cycle of larger and smaller full Moons every 14 lunar months. A supermoon happens whenever a full moon coincides with its perigee, which can occur multiple times in succession.
During this supermoon, the moon will be 220,055 miles from Earth, the closest a full moon will get this year. That means t will appear the biggest and brightest of the lot, or, in other words, it will be the most "super".
Steam rises from cooling towers of a power plant as the moon rises near Senftenberg, Germany, on October 15, 2024. The moon will be extra big and bright on Wednesday as the Hunter's supermoon graces the skies. Matthias Schrader/AP
"The term 'supermoon' is a vague, non-scientific term, and so different people define it in different ways," Darren Baskill, a physics and astronomy lecturer at the University of Sussex in the U.K., previously told Newsweek.
"One common definition is to say that we have a supermoon when the moon is within 90 percent of its average distance away from the Earth—but which average distance? Some say within 90 percent of the average Earth-moon separation for that particular month, while others say within 90 percent of the average Earth-moon separation for that entire year," Baskill said.
"There is no overall consensus. Depending on which of those definitions you use, you can have three or four supermoons per year."
When To View Comet A3 and the Supermoon
While Comet A3 is past its brightest as it heads back out into the outer reaches of the solar system, it's still visible with the naked eye for the next few nights. The best time to view the comet is about 45 minutes after sunset in the western sky.
"Comet A3 Tsuchinshan-ATLAS is fading quickly, with reports showing that it is halving in brightness every single day as it travels away from both the sun and us here on Earth," Baskill said. "But the good news is that as it does travel away from the sun, it is moving into higher, darker skies, which is at least slightly in our favor."
The moon is also at its best in the early evening as it pops up above the horizon. The reason for this is thanks to an optical illusion, which makes the moon appear even larger when nearby buildings and landscape are in the foreground.
The full moon does make the sky a little brighter, which can make the comet harder to spot, so binoculars or a telescope are recommended if you have them. Heading away from sources of light pollution, such as cities, will also help make the comet visible in all its glory.
As the comet moves away from us, it's getting higher in the sky, which means its visible for longer and is easier to see if buildings or hills are blocking your view.
To view both the supermoon and the comet you will, of course, need clear skies, so keep an eye on your local weather forecast. Below is a map from the National Weather Service showing the expected percentages of cloud cover across the U.S. tonight.
Sky cover forecast for the contiguous U.S., Wednesday, October 16. Clear skies will be needed to catch a glimpse of the comet and supermoon in tandem. National Weather Service
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