In this article
How it happens
The Full Moon sometimes passes through only the edge of Earth's umbra, the dark core of its shadow. Then a section of the Moon goes dark while the rest stays bright. If the Moon crosses more deeply, the bite grows larger, and in extreme cases the eclipse comes close to total.
The curved edge of the shadow is itself a small proof that Earth is round. Ancient observers used exactly that curve to argue the point.
What you see
- Slow start. About an hour before maximum, a dusky notch appears on one side of the Moon.
- The bite. The shadowed area looks brownish or grey, sometimes with a faint red hint along its border.
- Strong contrast. The still-bright part can wash out the dim part, so binoculars or a telescope help.
- Slow finish. The shadow retreats and the Moon becomes full again.
Magnitude and the table
Observatories describe depth with magnitude, the fraction of the Moon's diameter inside the umbra. A magnitude of 0.2 is a small nibble, while 0.9 leaves just a thin bright rim. The table shows the time of greatest eclipse in your time zone.
Visibility depends on location: you must be on the night side with the Moon above the horizon. Astronomy observatories list local timings.
Watching with confidence
You do not need eye protection at all, because moonlight is gentle. Bare eyes work well, and a pair of binoculars shows crater details along the edge of the shadow. Photography is easy with a tripod, even on a phone.
For the version where the whole Moon enters the shadow, see the total lunar eclipse, and for a faint shading with no dark bite, the penumbral lunar eclipse.
Meaning in tradition
Astrologers treat a partial lunar eclipse as a milder turning point than a total one, a time for letting go of something unfinished. It is a symbolic tradition and carries no danger. The full set of types is on the eclipses hub.
Questions people ask
Is a partial lunar eclipse worth watching?
Yes. The dark bite is clearly visible and the changing shape over a couple of hours is a good, calm sky event, especially with binoculars.
Can I look without eye protection?
Yes. Lunar eclipses are entirely safe to watch with eyes, binoculars or telescopes.
Why does the shadow look brown, not black?
Some sunlight still bends through Earth's atmosphere into the shadow, and filtered light tints the darkened part.