It's all very well digging into the theory -- what does this mean in practice? In particular, how often will I see an eclipse?
This page gives you some statistics about how often eclipses occur.
So how often can we see an eclipse? Well, as explained in Eclipse Cycles, there are two eclipse seasons per year (actually, one every 173 days) when an eclipse can occur. An eclipse season lasts for 37 days; since the Moon only takes 29 days to complete an orbit, we're guaranteed one solar and one lunar eclipse (which may or may not be total) every eclipse season. With an eclipse season happening a little more often than every 6 months, there are at least two -- and sometimes three -- in a year; so there should be at least 4 eclipses a year.
In fact, since one orbit of the Moon takes less time than the length of an eclipse season, it's quite possible to get two solar or two lunar eclipses in an eclipse season (but not two of each); this happens a bit more than every 4 years, on average, for solar eclipses, and about every 3 years for lunar eclipses. However, since the two eclipses have to be at either end of the season, the two eclipses are usually both small partial eclipses; but about every 300 years, a total solar eclipse and a partial solar eclipse occur in the same eclipse season. The last time this happened was in 1928; a tiny total eclipse in the far south, in May, was followed in June by a small partial eclipse in the far north. The next time this happens will be in July and August 2195.
So, every year sees at least 4 eclipses (2 solar and 2 lunar), somewhere on the Earth. About once in 3.5 years, 5 eclipses occur; 6 in a year happens ever 4.5 years or so; and you can get 7 eclipses in a year, but that's rare -- only about every 31 years. (The last year this happened was 1982; the next time will be 2038.)
Total eclipses are, of course, rarer. On average, a total solar eclipse happens about twice in three years, and total lunar eclipses are a little more frequent than that. It's possible to get 2 total solar eclipses in a year, but again this is rare; only every 170 years or so. However, two total lunar eclipses occur in a single year about once every 3.5 years, and 3 in a year about every 200 years.
Actually seeing an eclipse is a little more tricky, of course; you actually have to be in the right place at the right time. For solar eclipses, because the partial phase of a total solar eclipse covers a relatively large area, this can be seen about every 2 years, on average, from any given spot on the Earth. The much narrower track of the total eclipse falls over a particular place far less often -- the best guess is about every 360 years on the average, although they're distributed so randomly (in effect, though, of course, it's not really random) that a given spot might not see a total eclipse for centuries, or might see two within a few years. Some examples of the latter are shown in the USA Eclipse Bonanza page.
Lunar eclipses are much easier to see; because the action is happening on the Moon, and on the side facing us, anywhere that the Moon is up during the eclipse will see it (clouds permitting), whether it's partial or total.
The following statistics are extracted from the searchable eclipse database:
The database contains 24085 eclipses over 5000 years, from -1999 (2000 BC) to 3000 AD. There are between 4 and 7 eclipses in any calendar year; with an average of 4.82 eclipses per year.
7 eclipses occur in 1908, 1917, 1935, 1973, 1982, 2038, 2094, among others.
The database contains 10536 complete eclipse seasons.
This table shows the number of eclipse seasons which contained each combination of eclipse types:
Solar EclipsesThere are:
Since year 1000, 5 solar eclipses occur in 1255, 1805, 1935, 2206, 2709, 2774, 2839, 2904.
There is a maximum of 2 total solar eclipses in any calendar year. There are:
Since year 1000, 2 total solar eclipses occur in 1014, 1209, 1358, 1535, 1554, 1712, 1889, 2057, 2252, 2429, 2606, 2801, 2996.
There are 1360 double solar eclipse seasons (1 in 3.68 years); of which 16 involve a total eclipse (1 in 312.50 years):
-1859/05/24 19:43 S,T and -1859/06/23 02:56 S,P -1718/04/26 18:10 S,T and -1718/05/26 01:10 S,P -1451/06/12 21:06 S,P and -1451/07/12 04:02 S,T -1310/05/15 19:25 S,P and -1310/06/14 01:57 S,T -1169/04/17 17:40 S,P and -1169/05/17 00:17 S,T -716/06/16 16:43 S,T and -716/07/15 23:37 S,P -575/05/19 14:54 S,T and -575/06/17 21:29 S,P -434/04/21 12:56 S,T and -434/05/20 19:40 S,P -26/05/10 12:59 S,P and -26/06/08 20:12 S,T 654/04/22 16:02 S,P and 654/05/21 22:52 S,T 1107/06/22 14:28 S,T and 1107/07/21 21:19 S,P 1248/05/24 12:14 S,T and 1248/06/22 18:59 S,P 1928/05/19 13:24 S,T and 1928/06/17 20:27 S,P 2195/07/07 15:35 S,P and 2195/08/05 22:14 S,T 2459/05/03 02:15 S,P and 2459/06/01 09:39 S,T 2912/07/06 00:19 S,T and 2912/08/04 07:04 S,P
The database contains solar eclipses from saros series -13 to 190. There are 204 complete saros series (and 83 partial series). The number of eclipses in a series ranges from 70 (Saros 104, 116, 122, 123, 137, 138, 141, 144) to 86 (Saros 34, 52).
Lunar EclipsesThere are:
Of the 4479 penumbral eclipses, 191 are total penumbral eclipses (ie. penumbral magnitude >= 1.000); this is 4.3% of the penumbral eclipses, or 1.6% of all lunar eclipses; 1 every 26.18 years.
Since year 1000, 5 lunar eclipses occur in 1181, 1246, 1311, 1676, 1694, 1749, 1879, 2132, 2262, 2400, 2653, 2718, 2783, 2848, 2968.
There is a maximum of 3 total lunar eclipses in any calendar year. There are:
Since year 1000, 3 total lunar eclipses occur in 1414, 1479, 1544, 1917, 1982, 2485, 2550, 2615.
There are 1651 double lunar eclipse seasons (1 in 3.03 years); of which none involve a total eclipse.
The database contains lunar eclipses from saros series -20 to 183. There are 204 complete saros series (and 87 partial series). The number of eclipses in a series ranges from 71 (Saros 111, 113, 114, 128, 129, 132, 133, 135) to 87 (Saros 26, 43, 45).
Copyright (C) 1995-2006 Ian Cameron Smith.
visits since 18Aug05. Last modified: Sat May 3 11:44:25 PDT 2008 ($Revision: 1.5 $)