solar eclipse

A solar eclipse is the celestial event consisting of the Moon passing exactly between the Sun and the Earth, putting the Moon's shadow briefly on the Earth. A lunar eclipse occurs when the Moon's orbit places it in the Earth's shadow. Both occur when the Sun, the Earth, and the Moon are aligned (are positioned along a straight line). Eclipses do not occur every month because the Moon's orbital plane is tilted compared to the Earth's (the ecliptic), and the Moon's orbit retains roughly the same tilt through the course of a year such that most months, the Moon is never aligned with the Earth and the Sun. The Moon's orbit produces such alignments during two (or occasionally three) time-periods per year, termed eclipse seasons, each of which lasts roughly two months. The time of year of the eclipse seasons shifts earlier every year, because of an 18-year precession-cycle of the Moon's orbital plane.

Lunar eclipses are visible from all the Earth that is at night at the time, but solar eclipses partially block the Sun from just a portion of the Earth, and only some solar eclipses completely block the Sun anywhere on Earth: such a total solar eclipse (the complete blocking of the Sun) lasts just a minute or two at any specific Earth location that experiences it: the shadow moves across Earth, so a narrow strip of land thousands of miles long experiences the total eclipse.

Solar eclipses are used in the study of the Sun: total eclipses reveal a better view of the corona than coronagraphs.

Some recent and upcoming solar eclipses:

Types listed above:

• total - there is a region on Earth from which the Sun is totally covered.
• annular - there is such a region where Sunlight totally surrounds the moon.
• hybrid - some places get a total eclipse, others an annular eclipse.
• partial - only a portion of the Sun is blocked, i.e., no total or annular.