If you love all the stargazing opportunities we've been getting lately, set yourself a reminder to look up at the sky on Tuesday night. You can check out a super harvest blood moon, and a partial lunar eclipse. "Super harvest blood moon" almost sounds like a horror-movie title. It's not frightening, though, and it could make for an awesome evening outside, if you know what to look for. Let's break down that Halloween-esque name.
The harvest moon, arriving on Sept. 17, appears every year. It's simply the name given to the moon that happens closest to the autumn equinox, which takes place on Sept. 22 this year. But this year's harvest moon is also going to be a supermoon, as well as a blood moon, and these phenomena don't often happen together.
For it to be a supermoon, the moon has to be at its perigee, which means it's as close to the Earth as it can get during its orbit. This causes the moon to look bigger and brighter than it normally would. There are three to four supermoons a year, and they usually line up in a row. This year, the first supermoon was last month's rare blue supermoon. September will be the second. We're scheduled to get supermoons in October and November as well.
So then, what's a blood moon? Blood moons occur during partial or complete lunar eclipses. The Earth blocks the sun from fully lighting the moon, causing the sun's light to curl around the Earth's magnetic field. The field filters the sun's light, leaving mostly light from the red part of the color spectrum, thus turning the moon red. Similar to supermoons, blood moons occur a few times per year.
When is the super harvest blood moon?
The official full moon will occur on the evening of Tuesday, Sept. 17, and the morning of Wednesday, Sept. 18. Skygazers will be able to see a mostly full moon in the days leading up to the full moon and the days after. Looking at the sky any night between Sept. 16-20 will show you a moon that is over 90% full. So, if you miss it on Sept. 17, you can still enjoy the bigger and brighter moon on other days, it just won't be completely full.
The moon is the easiest celestial body to find in the sky. It'll rise out of the eastern sky for everyone in the US at around 7:50 p.m. ET on the East Coast and around 7:10 p.m. PT on the West Coast.
While you're looking up at the sky, keep an eye out for T Coronae Borealis, a white dwarf star that is set to go nova any day now and will show up as a new star in the sky for a while.
When is the partial lunar eclipse taking place?
Blood moons are caused by lunar eclipses, and one will be taking place on the evening of Sept. 17. The eclipse should be visible to the entire continental US, although the time of day will vary depending on where you are.
On the East Coast, the eclipse will start at around 8:41 p.m., reach its maximum at 10:44 p.m. and then end by 12:47 a.m. On the West Coast, it'll start at around 7:12 p.m., right as the moon climbs over the horizon. It'll reach its maximum at 7:44 p.m. and then finish up by 9:47 p.m. You can add or subtract an hour depending on your time zone to know when it'll hit you.
It won't be a huge eclipse. You'll see a sliver of the moon disappear briefly before coming back. The eclipse will affect the moon's color more than it will how well you can see it. If you're itching to see a full lunar eclipse, you won't have too long to wait. The next one is set for the evening of March 13, 2025.
None of the individual components of the super harvest blood moon are rare. Harvest moons happen every year, and supermoons happen three to four times a year. Blood moons also occur a few times every year. However, having all three events line up at the same time is actually quite unusual. The next time such an event is scheduled to happen is in September 2033, and after that, it won't happen again until 2042.