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 to hopefully provide the answers.
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 between 31 and 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 3½ years, 5 eclipses occur; 6 in a year happens ever 4½ years or so; and you can get 7 eclipses in a year, but that's rare — only about every 33 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 5,000 year eclipse catalog:
The database contains 23962 eclipses over 5000 years, from 2000 BC to 3000 AD. There are between 4 and 7 eclipses in any calendar year; with an average of 4.79 eclipses per year.
7 eclipses occur in years 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:
|Number||First Eclipse||Second Eclipse||Third Eclipse||Rate|
|179 seasons||penumbral lunar||annular solar||1 in 58.86|
|57 seasons||penumbral lunar||hybrid solar||1 in 184.84|
|462 seasons||penumbral lunar||total solar||1 in 22.81|
|1122 seasons||partial lunar||annular solar||1 in 9.39|
|167 seasons||partial lunar||hybrid solar||1 in 63.09|
|13 seasons||partial lunar||partial solar||1 in 810.46|
|782 seasons||partial lunar||total solar||1 in 13.47|
|178 seasons||total lunar||annular solar||1 in 59.19|
|12 seasons||total lunar||hybrid solar||1 in 878.00|
|730 seasons||total lunar||partial solar||1 in 14.43|
|127 seasons||total lunar||total solar||1 in 82.96|
|160 seasons||annular solar||penumbral lunar||1 in 65.85|
|1147 seasons||annular solar||partial lunar||1 in 9.19|
|178 seasons||annular solar||total lunar||1 in 59.19|
|85 seasons||hybrid solar||penumbral lunar||1 in 123.95|
|124 seasons||hybrid solar||partial lunar||1 in 84.97|
|5 seasons||hybrid solar||total lunar||1 in 2107.20|
|749 seasons||partial solar||total lunar||1 in 14.07|
|431 seasons||total solar||penumbral lunar||1 in 24.45|
|801 seasons||total solar||partial lunar||1 in 13.15|
|139 seasons||total solar||total lunar||1 in 75.80|
|941 seasons||penumbral lunar||annular solar||penumbral lunar||1 in 11.20|
|24 seasons||penumbral lunar||annular solar||partial lunar||1 in 439.00|
|119 seasons||penumbral lunar||hybrid solar||penumbral lunar||1 in 88.54|
|416 seasons||penumbral lunar||total solar||penumbral lunar||1 in 25.33|
|27 seasons||partial lunar||annular solar||penumbral lunar||1 in 390.22|
|1347 seasons||partial solar||total lunar||partial solar||1 in 7.82|
|6 seasons||partial solar||total lunar||total solar||1 in 1756.00|
|8 seasons||total solar||total lunar||partial solar||1 in 1317.00|
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.
Since year 1000, 2 total solar eclipses occur in 1014, 1209, 1358, 1535, 1554, 1712, 1889, 2057, 2252, 2429, 2606, 2801, 2996.
There are 1361 double solar eclipse seasons (1 in 3.67 years); of which 14 involve a total eclipse (1 in 357.14 years).
There are 479 sequences of 4 partial solar eclipses. There are no sequences of 3 or more annular or hybrid solar eclipses, and no occurrence of 2 or more successive total solar eclipses.
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, 131, 137, 138, 141, 144) to 86 (Saros 34, 52).
Across 7698 total, annular and hybrid eclipses the average magnitude is 0.996.
Of the 4378 penumbral eclipses, 141 are total penumbral eclipses (ie. penumbral magnitude >= 1.000); this is 3.2% of the penumbral eclipses, or 1.2% of all lunar eclipses; 1 every 35.46 years.
Since year 1000, 5 lunar eclipses occur in 1181, 1246, 1311, 1676, 1694, 1749, 1879, 2132, 2262, 2400, 2653, 2783, 2968.
There is a maximum of 3 total lunar eclipses in any calendar year.
Since year 1000, 3 total lunar eclipses occur in 1414, 1479, 1544, 1917, 1982, 2485, 2550, 2615.
There are 1527 double lunar eclipse seasons (1 in 3.27 years); of which none involve a total eclipse.
There are 142 tetrads: sequences of 4 or more total lunar eclipses. Between 1500 and 2500, the following eclipses form tetrad sequences:
The database contains lunar eclipses from saros series -20 to 183. There are 204 complete saros series (and 84 partial series). The number of eclipses in a series ranges from 70 (Saros 126) to 86 (Saros 47, 65).
The angular diameter of the Sun during an eclipse is on average 0.533°, and ranges from 0.524° (1.7% smaller than average), to 0.542° (1.7% larger than average).
The angular diameter of the Moon changes due to the rotation of the Earth. When the Moon is overhead, you are closer to it, because you're on the side of the Earth facing it; hence you are closer by up to the radius of the Earth, depending on how close to overhead it is. Because the Moon is very close to the Earth (compared to the planets and the Sun), this makes a measurable difference to its apparent size. Since any eclipse involves the Moon, this means that the Moon will be larger in the middle of an eclipse than at the start and end. This is why hybrid eclipses happen; the diagram on that page illustrates the effect.
The angular diameter of the Moon at the start and end of an eclipse is on average 0.524°, and ranges from 0.490° (6.6% smaller than average), to 0.558° (6.5% larger than average).
The angular diameter of the Moon at maximum eclipse is on average 0.531°, and ranges from 0.490° (7.8% smaller than average), to 0.568° (7.1% larger than average).