Earth between the Sun and the Moon

When the Moon
crosses our shadow.

A lunar eclipse tells the story of an alignment. It also lets us observe a gradual transformation of the disc.

A different phenomenon from phases

A lunar eclipse occurs at full Moon when the Moon passes through Earth’s penumbra or umbra. It does not happen every month because the lunar orbit is tilted relative to the plane of Earth’s orbit.

During totality, the Moon may turn coppery: sunlight passes through Earth’s atmosphere and reaches its surface. Its colour and brightness vary.

01 / Penumbral

A subtle darkening

The Moon crosses only Earth’s penumbra. The change can be difficult to see.

02 / Partial

A shadow on the disc

Part of the Moon enters the umbra. Follow the dark boundary over time.

03 / Total

The disc in shadow

The Moon enters Earth’s umbra completely. Its brightness falls; its colour becomes something to observe.

Preparing to observe an eclipse from Luxembourg

Check the eclipse circumstances and its area of visibility.
Convert the times to your time zone, accounting for daylight saving time.
Check that the Moon will be above a clear horizon during the stages you want to observe.
Record times, brightness and colour; for photographs, adjust exposure as the Moon darkens.

This page explains the phenomenon; it does not calculate upcoming dates or local visibility.

View upcoming eclipses at NASA ↗The observing sheet →

From book to sky

Adapted from the “La Lune” chapter of Steve Cimolino’s volume II, Comprendre comment explorer le ciel, manuscript dated 17 October 2026. The plates come from the book and have been resized for the web.

Photographs of both sides: NASA/Goddard/Arizona State University (LRO), Synchronous rotation. Annotated map: NASA photograph, Moon Phases, book annotations and approximate markers. Phase diagram: educational plate from volume II. NASA image use guidelines.

To explore further: NASA observing advice · Craters and maria · Lunar eclipses.

Discover volume II →