How often do eclipses happen?

Answer 1

There are generally two solar eclipses each year. About half of them are partial, and the remaining ones are divided between full and annular eclipses.

You can look up the catalog of all eclipses from 2000BC to 3000AD on the NASA Eclipse Web Page.

We tend to think of solar eclipses as being much more rare. However, the difference is that a solar eclipse is visible only across a narrow strip across the Earth. Since the Earth is 3/4 covered by water, there is a much higher probability that the eclipse will be visible at sea.

For example, the total solar eclipse of July 11, 2010 will be visible along a path across the South Pacific Ocean, including a few atolls in French Polynesia, Easter Island, and the southern tip of Chile and Argentina.

Answer 2

every millennium (thousand years)

Answer

Total solar eclipses are rare, they recur every 370 years on average.

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Answer 3

The maximum number of lunar eclipses that can occur per year is 3 (minimum 0), and the maximum number of solar eclipses is 5 (minimum 2). However, these numbers are very rare. On average, there are 1-2 lunar eclipses (partial or total) and 2-3 solar eclipses (partial, annular, or total) each year.

However, it should be noted that because during a solar eclipse the Moon's shadow does not cover the entire surface of the Earth (because the Moon is smaller than the Earth) not everyone on Earth will see the solar eclipse as it occurs. Instead, only those living along the path of the Moon's shadow (called the path of totality) will see it. On the other hand, everyone will be able to see a lunar eclipse. Thus, it is far more common for people to see a lunar eclipse at any given location than a solar eclipse. Put another way, the average time between two solar eclipses seen from the same location is about 360 years while the average time between two lunar eclipses seen from the same location is between 6 and 12 months.

Twice a year, there is a roughly 38 day window of time during which an eclipse could occur. These windows do not occur at the same time every year, so the term "season" does not refer to a particular time during the calendar year (Spring, Summer, etc.). The two eclipse seasons are separated by just under 6 months. Thus, the complete eclipse cycle lasts for roughly 345 days while the calendar year lasts for 365 days, so the eclipse seasons shift earlier and earlier each year - realigning again every 19 years.

A lunar eclipse occurs when the Moon passes through the Earth's shadow, which can only occur when the Moon is on the opposite side of the Earth from the Sun - which would normally be when we would see a Full Moon. Therefore, lunar eclipses can only occur during a Full Moon. Similarly, a solar eclipse occurs when the Moon passes in front of the Sun casting its shadow upon the surface of the Earth. This can only occur when the Moon is on the same side of the Earth as the Sun - which would normally be when there is a New Moon. The reason we don't normally get eclipses during Full and New Moons is because the Moon's orbit is tilted with respect to the Earth's orbit. During a Full Moon, the tilted path of the Moon usually takes it above or below the Earth's shadow and thus we get no lunar eclipse and just a normal Full Moon. During a New Moon, the tilted path of the Moon usually makes it such that the shadow of the Moon is cast above or below the surface of the Earth and thus we get no solar eclipse and just a normal New Moon.

However, during the two eclipse seasons the Moon's orbit is titled in such a way that it passes through the Earth's shadow and directly across the line of sight between the Earth and the Sun. If the Moon passes into a Full or New phase during this time an eclipse will occur. If a lunar and solar eclipse occur during the same season, they will be separated by about two weeks (the time it takes for the Moon to move from the opposite side of the Earth to the same side of the Earth as the Sun).

Answer 4

There are generally two solar eclipses each year. Of those, about half are "partial" solar eclipses in which the Moon covers up only a part of the Sun; you don't generally notice anything special about these. About 25% of solar eclipses are annular, and about 25% are total eclipses.

Because the Moon is small compared to the Earth, the area on Earth affected by an eclipse is quite small.

Answer 5

There are generally two lunar eclipses and two solar eclipses each year. Sometimes, depending on the precise alignment of the Sun, Earth and Moon, we will have two partial or penumbral eclipses instead of one of the total kind.

You can check the NASA Eclipse web site to see the exact timing and location of all eclipses.

Answer 6

There are generally two solar eclipses each year. Depending on the precise alignment of the sun, Moon and Earth, there are occasionally four partial or near eclipses instead of two actual eclipses.

However, the area of the Earth that falls in the Moon's shadow is fairly tiny, and many of the eclipses occur in inaccessible areas, so it is rare for an eclipse to hit a particular city or region.

The next total solar eclipse will be next year, on July 22, 2009. The Moon's shadow will hit the Earth start in the mid-Pacific ocean and cover a path across the southern end of Japan and across China and parts of India. Then there will be a total eclipse from the tip of South America almost to New Zealand, but mostly across the south Pacific ocean. In 2011 there will be four partial eclipses in the Arctic, Antarctic and one in Europe and Africa.

The next total really good solar eclipse for North America will be on August 21, 2017, from about Savannah, GA to Seattle, WA.

Answer 7

every 6 months For a lunar eclipse. solar eclipse take a lot longer.

Answer 8

Over several years, it'll average out to about 2.3 each year,

but it can vary between 1 and 5 in any single year.