How solar eclipse and lunar eclipse are caused?

CSS Everyday Science Paper 2015

Table of Contents

Question: How solar eclipse and lunar eclipse are caused?

Solution:

ECLIPSES

Eclipse is the obscuring of one celestial body by another, particularly that of the sun or moon. Two kinds of eclipses involve the earth: those of the moon, or lunar eclipses; and those of the sun, or solar eclipses.

Lunar Eclipse

A lunar eclipse occurs when the earth is between the sun and the moon and its shadow darkens the moon. The earth casts a long, conical shadow in space. At any point within that cone the light of the sun is wholly obscured. Surrounding the shadow cone, also called the umbra, is an area of partial shadow called the penumbra. Lunar eclipse would always occur when moon is in full-moon phase.

A total lunar eclipse occurs when the moon is completely in the umbral region. If it moves directly through the centre, it is obscured for about 2 – 4 hours. If it does not pass through the centre, the period of totality is less and may last for only an instant if the moon travels through the very edge of the umbra.

Fig: Lunar Eclipse

A partial lunar eclipse occurs when only a part of the moon enters the umbra & is obscured.

Check also: General Science MCQs for CSS

Solar Eclipse

A solar eclipse occurs when the moon is between the sun and the earth and its shadow moves across the face of the earth. Solar eclipse always occurs at the time of new moon. Total solar eclipses occur when the moon’s umbra reaches the earth.

The maximum duration of a total solar eclipse is about 7.5 minutes, but these are rare, occurring only once in several thousand years. A total eclipse is usually visible for about 3 minutes.