Lunar Eclipse Timings: Contacts, Totality and Your City's View

Why can two cities see different parts of one lunar eclipse?

Read the event's contact table, its time convention and its visibility map together. This guide uses an invented schedule to explain that process. It does not list the next eclipse or provide live contact predictions for a city.

Full Moon is necessary, but it is not enough

During a lunar eclipse the Moon passes through Earth's shadow around the full-Moon phase. As NASA explains, the Moon's orbit is tilted relative to Earth's orbital plane. Most full Moons pass above or below the alignment needed for an eclipse.

Therefore a Purnima date, an almost fully illuminated Moon icon or a full-Moon timestamp does not by itself establish an eclipse. The orbit's alignment with the shadow matters too. See the phase and tithi guide for the distinction between the full-Moon instant and the Purnima interval.

The lunar nodes help describe where the orbit crosses the ecliptic. Their use in a chart is explained in the Rahu–Ketu calculation guide. A natal node label is not a substitute for calculating an eclipse event.

Penumbral, partial and total: which shadow is involved?

The penumbra is the outer region of partial shadow. A penumbral lunar eclipse can produce a subtle dimming that is difficult to notice. The umbra is the central shadow: a partial eclipse carries part of the Moon into it, while a total eclipse carries the entire disk inside.

A total event includes stages before and after totality. This is why its first listed start time may be much earlier than the beginning of the completely immersed stage. Conversely, a penumbral event has no umbral contacts, and a partial event has no totality interval. Missing U2 and U3 entries are not necessarily missing data.

“Total” describes the Moon's relation to the umbra during the event. It does not mean every city sees every stage, and it does not describe how long your local Moon remains above the horizon.

Read P1, U1, U2, U3, U4 and P4

The NASA figure key identifies the contacts at the shadow boundaries. P1 and P4 mark the beginning and end of the penumbral passage. U1 and U4 bracket the umbral passage. U2 and U3 bracket totality when the whole lunar disk is inside the umbra.

All values below are invented UTC clock readings on one unspecified date. They are chosen for arithmetic practice, not taken from an actual eclipse.

Do not interpret P1 as the moment a clearly visible dark edge must appear. The earliest penumbral change is too slight for such a promise. Also distinguish a separate “greatest eclipse” entry from U2: greatest eclipse refers to the Moon's closest approach to the shadow axis, rather than the start of totality.

Calculate four durations without mixing the stages

The NASA catalog key defines the duration fields by their contact pairs. Apply those pairs to the teaching schedule:

• Whole penumbral passage: P4 − P1 = 22:20 − 17:30 = 290 minutes.
• Whole umbral passage, including totality: U4 − U1 = 21:25 − 18:25 = 180 minutes.
• Totality: U3 − U2 = 20:20 − 19:30 = 50 minutes.
• Partial-only portions combined: 180 − 50 = 130 minutes.

The umbral duration already contains the totality duration. Adding 180 and 50 would count totality twice. If a catalog labels the U1-to-U4 duration “partial,” read its definition: for a total eclipse that interval spans the intervening total stage as well.

Here the two partial-only shoulders are each 65 minutes. Their equality belongs to this invented schedule; it is not a rule to impose on every published eclipse table.

Four local views of the same schedule

Assume the following above-horizon intervals for four fictional locations. Ignore clouds, terrain and twilight for this arithmetic exercise. A geometric overlap is an opportunity for visibility, not a guarantee of a clear view.

A has the Moon above the assumed horizon throughout the event. It has all 180 minutes of the umbral passage and all 50 minutes of totality available. B has moonrise at 20:00, after totality has begun, leaving only 20 minutes before U3.

C has moonset at 19:45, giving 15 minutes between U2 and that setting time. D has no overlap with the eclipse at all. The event remains a total lunar eclipse in every row; its local availability changes.

To check an overlap, take the later of the two start times and the earlier of the two end times. Subtract only if the resulting end is later than the resulting start. If the Moon rises at or after U3, there is no positive-duration totality window at that location.

Check the date, time zone and time scale

First put contact times and moonrise/moonset on a consistent dated timeline. A local event after midnight can belong to the following civil date. Comparing 00:20 with 23:50 as undated clock numbers would reverse their actual order when they straddle midnight.

Time scale and time zone are separate labels. NASA's figure documentation, for example, identifies Terrestrial Dynamical Time for a greatest-eclipse field; other published diagram fields can use Universal Time. Read each table's legend. Do not treat a TT/TD value as UTC merely by adding a local time-zone offset.

The USNO diagram explanation describes its UT contact labels and visibility maps. Use the documentation for the particular product you are reading, rather than assuming every eclipse graphic uses one format.

A practical reading order for your location

1. Choose the actual eclipse and read the publisher's date and time legend.
2. Identify its type and the contact pairs that exist.
3. Find the location on the eclipse visibility map.
4. Check moonrise, moonset and altitude for the same event and location.
5. Convert dated times consistently before calculating overlaps.
6. Then consider the local horizon and weather for an observing plan.

Astrogyana's moonrise and moonset tool helps with the horizon part of this comparison; it does not calculate the eclipse contacts in this article. The after-midnight guide explains how to read a change of civil date. Keep astronomical event times separate from any observance rules supplied by a particular tradition.

Frequently asked questions