How we calculate
UmbraLux calculates every date and time on this page itself, with the astronomy library astronomy-engine – the same calculation the UmbraLux app uses for its charts. As usual in astrology, positions are measured in the tropical zodiac: the signs start at the vernal equinox and span 30° each.
For each eclipse we calculate the moment of greatest eclipse and the times when the Moon enters and leaves the Earth's penumbra and umbra, plus the Moon's altitude for every place named. Like NASA's catalogue, we enlarge the Earth's shadow for the atmosphere (Danjon's rule). The magnitude is the share of the Moon's diameter inside the umbra.
An automated test compares every eclipse of 2026 and 2027 with NASA's Five Millennium Catalog (Espenak and Meeus): kind and magnitude agree, the moment of greatest eclipse lies within 10 seconds, the length of the phases within 0.2 minutes. For future years every calculation estimates the Earth's rotation (ΔT); a few seconds depend on it.
How a lunar eclipse happens
A lunar eclipse happens only at full moon, when Sun, Earth and Moon line up almost exactly and the Moon passes through the Earth's shadow. Because the Moon's orbit is tilted about 5° to the Earth's, the Moon usually passes above or below the shadow, which is why there is not an eclipse every month. Unlike a solar eclipse, it can be seen from everywhere the Moon is above the horizon.
Questions about lunar eclipses
Is there a lunar eclipse today?
There is no lunar eclipse today. The next lunar eclipse is on Saturday, February 20, 2027 (in 130 days): a penumbral lunar eclipse. From Germany, Austria and Switzerland it can be seen from beginning to end, weather permitting. In Berlin the Moon stands 47° high at the maximum. A penumbral eclipse is hard to notice with the naked eye; the Moon only dims slightly.
When can the next lunar eclipse be seen from Germany?
Until the end of 2027: February 20, 2027 (penumbral lunar eclipse).
Why does the Moon turn red in a lunar eclipse?
In the umbra, the only sunlight reaching the Moon has been bent through the Earth's atmosphere. The atmosphere scatters the blue light away and lets the red through, as at sunset. How dark and how red the Moon turns depends on the state of the atmosphere.
What is a penumbral lunar eclipse?
The Moon only passes through the Earth's penumbra, where the Sun is only partly hidden. It dims very little, which is hard to see with the naked eye. It does not enter the umbra.
Do I need eye protection for a lunar eclipse?
No. A lunar eclipse is safe to watch with the naked eye, binoculars or a telescope.
By year
More calendars
Matching calculators
- Birth moon phaseNew moon, full moon or in between: the phase, the light and the age of the Moon at your birth.
- Moon signThe sign the Moon stood in when you were born.
- Birth chartChart wheel with planets, Placidus houses, Ascendant, MC and aspects.
- Lunar nodesNorth and South Node by sign and house, after the true node.
Sources
- astronomy-engine (Don Cross) : the calculation library the UmbraLux app uses too
- NASA Eclipse Web Site: Five Millennium Catalog of Lunar Eclipses (Espenak & Meeus) : reference values of our test