Why October’s full moon looks a bit larger and brighter than usual
October’s full moon – the first of the autumn season – roselate on Monday and into early Tuesday. Called the Harvest Moon due to its proximity to the autumnal equinox, it is also the first of three consecutive supermoons that will grace nighttime skies to end 2025.
This supermoon reached 100% fullness at 2:02 a.m. Tuesday and will be 97 percent or greater fullness through Wednesday.
Since the moon’s orbit around our planet isn’t a perfect circle, a supermoon occurs when the moon is both at its fullest and its closest to earth – what scientists call a perigee. During a supermoon, our glowing natural satellite can appear as much as 14% larger and 30% brighter than normal.
The closest approach to earth is about 30,000 miles nearer than when the moon is at its furthest.
The next two supermoons this year will rise on Nov. 5 and Dec. 4.
How this moon got its name
The moniker Harvest Moon is perhaps an unsurprising one at first blush – arriving near the time autumn becomes official; when the bounty of summer is gathered from the fields before winter sets in.
But because the Harvest Moon is defined as full moon nearest in time to the autumnal equinox, it’s a name that can be used during multiple months.
The October full moon is more often called the Hunter Moon because September’s Corn Moon often takes the title Harvest Moon. This is because the September full moon is typically closest to the fall equinox.
Indeed, this month’s full moon is happening about half a day closer to the Sept. 22 equinox than September’s full moon did.
An October Harvest Moon happens every three to four years. It was last witnessed in 2020 and will next occur in 2028.
How to view the moon
The best way to get a look at the supermoon is to gaze upward near and after dark. It will rise in the eastern sky.
In Washington, D.C., for example, the moon will rise at 6:22 p.m., about 20 minutes prior to sunset. In Boston, the supermoon will claw above the horizon at 5:55 p.m. On the other side of the country, Spokane residents will see it emerge at 6:18 p.m., also roughly 20 minutes prior to sunset.
With the moon rising right around the time the sun goes down, it will be well placed above the horizon during the so-called “blue hour,” which is a very pleasing time to view or photograph it given the soft lighting. During the time the moon is nearer the horizon, its largeness is further magnified by visual effects called the moon illusion.
If waiting for total darkness and with thoughts of viewing other celestial objects, typical night sky watching is best done after 30 minutes of acclimatizing one’s eyes to the dark while also seeking out areas with little in the way of light pollution, generally outside of cities. In the case of the supermoon, though, well-placed architectural elements can add to the viewing experience, especially if done through the lens of a camera.
Otherwise, consider the comfort of a chair or blanket and maybe bring a snack if planning on being out for long.
Will weather or clouds affect the view?
Weather conditions appear to be most favorable across western states and probably as far east as the Rockies, where clouds should be the least likely to obscure the view. Much of the East Coast should also eke out a good view ahead of clouds associated with an approaching cold front.
In the Midwest region and toward the Appalachians, cloudiness may be more of a concern, although no major weather systems seem likely. Perhaps some showers or a storm. Even in areas that have a good deal of cloud cover, many will still be able to take a peek at the moon through any breaks.
As far as other night sky observations this month, the Orionid meteor shower reaches its apex in late October. The shower runs from Sept. 26 to Nov. 22, peaking on Oct. 21, during a new moon, which should help the shower stand out. As many as 20 meteors per hour will be visible, all thanks to Earth passing through debris from Halley’s Comet.