Retired NASA eclipse scientist Fred Espenak has been observing the night sky since he was eight and plans to look up again for the upcoming lunar eclipse Sunday (May 15).
After staring at the sky for about six decades, the Arizona native said he still enjoys watching the shift in shade as the moon turns red during a total lunar eclipse and fully penetrates Earth’s deep shadow. Read our full Superflower Blood Moon Lunar Eclipse guide to prepare for the epic lunar event.
webcast: How to watch Super Flower Blood Moon lunar eclipse online
“You look at it 10 seconds before or 10 seconds after, you can’t tell the difference,” Espenak told Space.com of lunar eclipses. “It’s more of a gradual effect. You see changes minute by minute, but not second by second.”
The Flower Moon eclipse will be visible throughout the full phase from parts of the Americas, Antarctica, Europe, Africa and the eastern Pacific. This eclipse shows a moon appearing slightly larger, on the verge of supermoon status. If you’re hoping to photograph the moon or want to prepare your gear for the total lunar eclipse, check out our best cameras for astrophotography and best lenses for astrophotography. Read our guides to photographing a lunar eclipse as well as photographing the moon with a camera for some helpful tips on planning your lunar photo session.
Not everyone agrees that the flower full moon is a supermoon due to differing definitions. Espenak’s definition is based on the very first supermoon, when astrologer Richard Nolle defined it in 1979 as a full moon that is within 90% of its closest point in orbit.
“That’s the definition I use because that was the first one. As far as I’m concerned, that sets the precedent,” he said. “But first of all, that 90% is purely arbitrary. There’s no real justification for why it should be 90% or 89 or 91.”
But Espenak calculates supermoons to also account for changes in the moon’s orbit during each lunar cycle, including perigee (closest point) and apogee (farthest point). NASA, which follows the strict 90% definition, says the flower moon is not a supermoon, but that June’s full moon will be one.
Espenak’s rationale boils down to lunar variability. “The perigee point and the apogee point of each individual [moon] The orbit varies from one orbit to another,” he said. That’s because the Earth and the sun’s gravity pull the moon across its orbits.
“The limits of what you get as a supermoon vary from one orbit to another,” he added. “To determine whether or not a particular moon is a supermoon, one must look at the moon’s specific orbit during that lunar cycle.” (A lunar month is a lunar month, or the time that elapses between new moons.)
Epsenak’s definition of Supermoon will represent the next four consecutive Full Moons as Supermoons: May 16th, June 14th, July 13th and August 12th. But he noted that stripes aren’t particularly uncommon. According to his website, like 2024, 2023 will also see four consecutive full super moons. Even 2025 has three in a row.
“About every 14 months you get a series of moons that are wider than that 90 percent threshold. So very often we get two or more likely three to four every 14 months,” he explained. However, he added, the relative size of the larger full moon is so small that even he can’t easily tell the difference just by looking at the sky.
While the size of the Supermoon will be subtle, the eclipse will become quite interesting once it makes the first umbraic contact with the Moon. The penumbral or brighter eclipse will introduce subtle shading, but the umbra, Espenak said, will “look like the Cookie Monster took a chunk out of the moon.”
“You don’t really see the color until you get close to totality,” he said. The Blood Moon, he added, should be very easy to spot within minutes of totality, although that will depend on the lighting and atmospheric conditions in your area.
“It’s easier to see subtle colors and features in dark places,” he said. “Attentive observers will notice that the part of the moon that lies deep in shadow can see some color in the last five to 10 minutes of the partial phases as we approach totality.”
However, the blood moon may not look exactly red. “It ranges from bright orange to fire engine red to a dark tan color and an almost invisible dark brown gray,” Espenak said. “Mostly, though, it’s orange to red, and that’s because of the colors caused by sunlight filtering through Earth’s atmosphere.”
While the timing depends on your location, TimeandDate.com says the partial eclipse phase of the lunar eclipse begins on May 15 at 10:28 p.m. EDT (0228 GMT on May 16). It will reach the red-hued apex of the Blood Moon at 00:11 EDT (0411 GMT) on May 16. The event ends at 1:55 pm EDT (0555 GMT). Note that the penumbral eclipse begins about an hour earlier and ends about an hour after the partial eclipse.
Editor’s note: If you capture an amazing lunar eclipse photo (or your own Eclipse webcast) and would like to share it with Space.com readers, send your photos, comments, and your name and location to spacephotos@space.com.
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