In September 2024, the Moon will provide a celestial show with its first and only partial lunar eclipse of the year. This astronomical event will delight skywatchers as the Moon slips into Earth’s umbral shadow. Additionally, the Moon will also occult Saturn and hide the stars of the Pleiades during this remarkable month of September.
What to Expect: The September 2024 Partial Lunar Eclipse
The upcoming partial lunar eclipse on the night of September 17-18, 2024, will resemble the one that occurred on April 25, 2013. Observers across much of the Americas, Europe, and Africa will have a chance to witness this event. Best of all, it takes place at a convenient time for many skywatchers without sacrificing too much sleep.
Those in the Americas will enjoy the eclipse during the evening hours, while observers in Europe and Africa will need to stay up a little later, as the eclipse occurs in the early hours after midnight in these regions.
Understanding the Eclipse: A Minor but Fascinating Event
While this partial lunar eclipse is classified as minor, it still holds great fascination for observers. The eclipse will reach a magnitude of 0.09, meaning that Earth’s shadow will cover approximately 9% of the Moon’s diameter. In terms of total area, or obscuration, around 3.8% of the Moon will be enveloped in Earth’s umbral shadow at its peak.
The duration of the eclipse’s main phase is relatively short. The Moon will only spend 65 minutes within the umbra, Earth’s darkest shadow. The rest of the time, the Moon will linger in the penumbral shadow, which is Earth’s lighter, outer shadow. The shadow will appear to move across the Moon from the northeastern limb to the northwestern limb as the Moon travels eastward at a rapid pace of around 3,960 kilometers per hour (2,460 mph).
Eclipse Timing and Visibility by Region
For skywatchers in North America, the eclipse will begin in the evening hours, making it a convenient event for viewing. Here’s a breakdown of the eclipse phases in Universal Time (UT) and conversions for various North American time zones:
| Eclipse Event | UT | ADT | EDT | CDT | MDT | PDT | AKDT |
|---|---|---|---|---|---|---|---|
| Penumbra first visible? | ~1:30 | ~10:30 p.m. | ~9:30 p.m. | ~8:30 p.m. | ~7:30 p.m. | — | — |
| Partial eclipse begins | 2:12 | 11:12 p.m. | 10:12 p.m. | 9:12 p.m. | 8:12 p.m. | 7:12 p.m. | — |
| Mid-eclipse | 2:44 | 11:44 p.m. | 10:44 p.m. | 9:44 p.m. | 8:44 p.m. | 7:44 p.m. | — |
| Partial eclipse ends | 3:17 | 12:17 a.m. | 11:17 p.m. | 10:17 p.m. | 9:17 p.m. | 8:17 p.m. | 7:17 p.m. |
| Penumbra last visible? | ~4:10 | 1:10 a.m. | 12:10 a.m. | 11:10 p.m. | 10:10 p.m. | 9:10 p.m. | 8:10 p.m. |
Regions marked with dashes indicate that the Moon will still be below the horizon during those phases. For the best viewing experience, be sure to check your local times and plan accordingly.
The Harvest Moon: Closer and Bigger Than Usual
Adding to the excitement, this eclipse coincides with the Harvest Moon, which will appear larger and brighter than usual. This is because the Moon will be near perigee, its closest approach to Earth, on the morning of September 18, just hours after the eclipse.
The Moon will swell to an apparent diameter of 33.7 arcminutes, about 3 arcminutes larger than its average size. Without this extra size, the shadowed portion of the eclipse would be even smaller and less noticeable. This Harvest Moon will be the second-closest full Moon of the year, with only October’s Hunter’s Moon appearing closer.
Though the difference in size between a perigean Moon and an apogean Moon (when the Moon is farthest from Earth) may not be easily distinguishable to the naked eye, you can compare them by taking photos. Snap a picture of this month’s full Moon and do the same during the apogee full Moon on April 13, 2025. Place the two images side by side, and the size difference will be clear.
Watching the Eclipse: Tips and Techniques
You don’t need any special equipment to observe this eclipse. The event is easily visible with the naked eye, but using binoculars or a telescope will enhance the experience. About 30 to 40 minutes before the partial eclipse begins, you may notice a subtle darkening, called penumbral shading, along the Moon’s eastern limb. As the Moon moves deeper into the penumbral shadow, the shading will become more apparent.
When the eclipse reaches its partial phase, a gray shadow will slowly creep over the lunar north pole. Through a telescope, this shadow will appear soft and fuzzy, like a gathering storm cloud rolling over the lunar surface. The contrast between the bright lunar surface and the darkening shadow is a striking sight, especially when viewed up close.
The Science of Lunar Shadows
The Moon’s shadow during a lunar eclipse consists of two parts: the penumbra and the umbra. The penumbral shadow is the lighter, outer part, where Earth partially blocks sunlight, while the umbra is the darker, inner shadow, where Earth completely blocks sunlight. This combination of light and shadow creates a soft, blended appearance, especially at the edge of the umbra.
Imagine the shadows cast by tree branches on a snowy path. The darker parts of the shadow are where the branches fully block the light, while the edges are softer, where some light still filters through. The Moon’s shadow behaves similarly, creating a smooth, gradual transition from light to dark.
Conclusion: Don’t Miss This Unique Celestial Event
The partial lunar eclipse of September 17-18, 2024, promises to be a memorable event for skywatchers around the world. Although it is considered a minor eclipse, the combination of the Harvest Moon’s larger-than-usual size and the opportunity to observe the eclipse at convenient times makes it a must-see. Whether you’re using a telescope, binoculars, or just your eyes, be sure to step outside and catch this fascinating celestial show.
This event is not only an opportunity to witness the Moon dipping into Earth’s shadow but also a chance to appreciate the intricate dance between our planet, the Sun, and the Moon.
