Introduction

A lunar eclipse occurs whenever the Moon passes through Earth's shadow. At least two lunar eclipses and as many as five occur every year.

The periodicity and recurrence of lunar eclipses is governed by the Saros cycle, a period of approximately 6,585.3 days (18 years 11 days 8 hours). When two eclipses are separated by a period of one Saros, they share a very similar geometry. The two eclipses occur at the same node with the Moon at nearly the same distance from Earth and the same time of year due to a harmonic in three cycles of the Moon's orbit. Thus, the Saros is useful for organizing eclipses into families or series. Each series typically lasts 12 to 15 centuries and contains about 70 to 80 eclipses. Every saros series begins with a number of penumbral lunar eclipses. The series will then produce several dozen partial eclipses, followed by several dozen total eclipses. The later portion of the series produces another set of partial eclipses before ending with a final group of penumbral eclipses.

Catalog of Lunar Eclipses of Saros 173

The table below lists the concise characteristics of every lunar eclipse belonging to Saros 173 . The date and time of each eclipse is given for the instant of Greatest Eclipse. For eclipses between the years -1999 to 3000, the calendar date links to a web page containing additional details along with a diagram of the eclipse geometry and a map showing the geographic region of eclipse visibility for that eclipse. A description of each parameter in the catalog table can be found in Key to Saros Catalog of Lunar Eclipses.

Statistics for Lunar Eclipses of Saros 173

Lunar eclipses of Saros 173 all occur at the Moon’s descending node and the Moon moves northward with each eclipse. The series will begin with a penumbral eclipse near the southern edge of the penumbra on 2787 Apr 24. The series will end with a penumbral eclipse near the northern edge of the penumbra on 4067 Jun 11. The total duration of Saros series 173 is 1280.14 years.

Saros 173 is composed of 72 lunar eclipses as follows:

The 72 lunar eclipses of Saros 173 occur in the order of 8N 7P 27T 9P 21N which corresponds to the following.

The longest and shortest eclipses of Saros 173 as well as largest and smallest partial eclipses appear below.

Links to Additional Lunar Eclipse Predictions

• Home - home page of EclipseWise with predictions for both Solar and lunar eclipses

• Lunar Eclipses - primary page for lunar eclipse predictions
• Lunar Eclipse Links - detailed directory of links
• Lunar Eclipse Basics - a primer on lunar eclipses

• Catalog of Lunar Eclipse Saros Series - covers Saros series -30 through 190
• Six Millennium Catalog of Lunar Eclipses - from -2999 to +3000 (3000 BCE to 3000 CE)
• Javascript Lunar Eclipse Explorer - calculate all lunar eclipses visible from a city

• Thousand Year Canon of Lunar Eclipses 1501 to 2500 - link to the publication

• Catalog of Lunar Eclipses of Historical Interest - includes a list of noteworthy lunar eclipses from history
• Lunar Eclipses of History (Reis) - a contributed article from Norma Reis

• MrEclipse.com - eclipse resources and tips on photography
• Lunar Eclipses for Beginners - a primer on lunar eclipse basics
• How to Photograph a Lunar Eclipse - instructions for imaging an eclipse of the Sun
• MrEclipse Photo Index - an index of lunar eclipse photographs

Eclipse Publications

by Fred Espenak

Calendar

The Gregorian calendar (also called the Western calendar) is internationally the most widely used civil calendar. It is named for Pope Gregory XIII, who introduced it in 1582. On this website, the Gregorian calendar is used for all calendar dates from 1582 Oct 15 onwards. Before that date, the Julian calendar is used. For more information on this topic, see Calendar Dates.

The Julian calendar does not include the year 0. Thus the year 1 BCE is followed by the year 1 CE (See: BCE/CE Dating Conventions). This is awkward for arithmetic calculations. Years in this catalog are numbered astronomically and include the year 0. Historians should note there is a difference of one year between astronomical dates and BCE dates. Thus, the astronomical year 0 corresponds to 1 BCE, and astronomical year -1 corresponds to 2 BCE, etc..

Eclipse Predictions

The eclipse predictions presented here were generated using the JPL DE406 solar and lunar ephemerides. The lunar coordinates have been calculated with respect to the Moon's Center of Mass.

The largest uncertainty in the eclipse predictions is caused by fluctuations in Earth's rotation due primarily to tidal friction of the Moon. The resultant drift in apparent clock time is expressed as ΔT and is determined as follows:

1. pre-1950's: ΔT calculated from empirical fits to historical records derived by Morrison and Stephenson (2004)
2. 1955-present: ΔT obtained from published observations
3. future: ΔT is extrapolated from current values weighted by the long term trend from tidal effects

A series of polynomial expressions have been derived to simplify the evaluation of ΔT for any time from -2999 to +3000. The uncertainty in ΔT over this period can be estimated from scatter in the measurements.

Acknowledgments

Some of the content on this web site is based on the books Five Millennium Canon of Lunar Eclipses: -1999 to +3000 and Thousand Year Canon of Lunar Eclipses 1501 to 2500. All eclipse calculations are by Fred Espenak, and he assumes full responsibility for their accuracy.

Permission is granted to reproduce eclipse data when accompanied by a link to this page and an acknowledgment:

"Eclipse Predictions by Fred Espenak, www.EclipseWise.com"

The use of diagrams and maps is permitted provided that they are NOT altered (except for re-sizing) and the embedded credit line is NOT removed or covered.