Tahiti Eclipse

What is an eclipse?

Each planet of the solar system takes its brightness from the sun. A celestial object is partially or totally eclipsed when it is plunged into the shadow of another one, just in part or in totality.

What is a solar Eclipse?

A solar eclipse occurs on new moon. The moon passes between the Earth and the Sun, consequently it hides the Sun from an observer located on Earth, and casts its shadow on the surface of the earth.

By an extraordinary coincidence, the Moon which is 400 times smaller than the Sun is also 400 times closer. Thus, the apparent diameters of the two objects are almost identical to a terrestrial point of view.
The total solar eclipse happens when the moon is close enough to the earth and then totally hides the sun. This is the case of the upcoming total eclipse of July 2010.
The partial eclipse is when the Moon partly hides the sun out of the annular eclipses conditions.

An annular eclipse occurs when the apparent diameter of the Moon is smaller than the apparent diameter of the Sun, and therefore the moon does not hide the Sun completely. The visible part of the Sun takes the form of a bright ring shining around the dark disk of the moon.

Frequency of eclipses

As a minimum, four eclipses occur a year, with two lunar eclipses and two solar eclipses. The maximum number of eclipses is seven: two solar eclipses, and two lunar eclipses and for remaining, all combinations are possible.

The same eclipse repeats itself every 6585.3 days or 18 years and 10, 11 or 12 days according to the distribution of leap years. This period is called the Saros. With Saros, one can find the exact date of an eclipse that happened many centuries earlier, just as one can predict the following eclipse.

What makes an eclipse so exceptional is that it never occurs again by the next 370 years in the same place.

A Saros counts about 84 eclipses: 42 of moon eclipses and 42 solar eclipses. Most of them are partial eclipses. Moreover, as the moon is going far away from the earth of 3 cm every year away from the Earth each year, in hundreds of centuries, total eclipses will no longer exist.

(Source: CNES)