Two New Moons in the same month? Since there’s 29 days between New Moons, just occasionally there can be two in a month, which is what’s happening on Wednesday, July 31. Consequently, the world’s night skies will be free of moonlight for the next two weekends. That makes it the perfect time for some summer stargazing!
What is a ‘black moon’?
It’s not an astronomical term, and shouldn’t be confused with “blood moon,” which refers to the visual phenomenon of a lunar eclipse (and also isn’t an astronomical term). A “black moon” refers to the second of two New Moons in the same calendar month, though according to Farmer’s Almanac it can also refer to the third of four New Moons in any one season. That’s the exact opposite of a “blue moon,” which means the third of four full moons in any one season.
How often does a ‘black moon’ occur?
Every 32 months there are two New Moons in the same calendar month, though the one happening this summer is changeable. For North Americans, the next New Moon occurs on Wednesday, July 31, for the second time in July, hence it’s a “black moon.” However, in most of the rest of the world the New Moon occurs on Thursday Aug. 1, so their “black moon” is the next one on Friday, Aug. 30.
Is it also a supermoon?
Technically, yes. Though the term “supermoon” is typically used to refer to a Full Moon, all it means is that the moon is near the closest point to Earth on its slightly elliptical egg-shaped orbit of Earth. That happens every month, so in theory there’s a “supermoon” once per month. This month, the moon comes closest to Earth while also being a New Moon. Since a New Moon is almost directly between Earth and the Sun, only the far side of the Moon is illuminated, so nothing is visible from Earth. This kind of “supermoon” is one you cannot see.
When are the best nights for stargazing?
Stargazers have a secret. They know that to see a sky full of stars you have to look during a 10-night window when there is no bright moon in the sky. That calculates to about a week before New Moon and about three days afterwards. So that makes July 25 through Aug. 3 ideal for stargazing.
How to see the Milky Way
As luck would have it, our planet is tilted towards the Milky Way during summer, with August the very best time to see the Galactic Center from the northern hemisphere. If you want to see the Milky Way arch overhead, get yourself to a dark sky site such as a national park, or anywhere about 40 miles from the nearest town. From about 10 p.m., the Milky Way should be visible. Just give your eyes a few minutes to adjust for proper night vision (20 minutes is recommended).
We've also created a handy guide on where and when to get the best photos of the Milky Way this year.
How to see shooting stars
In another stroke of celestial luck, the end of July is also the peak time for the Southern Delta Aquariids meteor shower. Although not many shooting stars per hour are promised (perhaps just 15), they can be bright. The lack of moonlight will really help, and you may even see some early shooting stars from the year’s best, the Perseids meteor shower, which peaks in mid-August.
Though the term “black moon” has a few meanings, one thing is for sure. With the moon down and the sky adorned with falling stars and the Milky Way, there is no better time in 2019 to go stargazing than the next two weekends.