4th Class Science Our Universe Eclipses


Category : 4th Class

*       Eclipses


Eclipse is a play of light and shadow. Eclipse simply means shielding away or hiding away something in ones shadow. Focus a torch towards a wall. Now put your hand between the wall and the lighted torch. Can you see the shadow of the hand on the wall? Yes, this is what happens during the eclipses. This process of shadow formation and shielding of one object's view happens in space too. The Earth and the Moon also cast shadow in space when sunlight falls on them. This causes solar and lunar eclipses. Simply we can say that depending on the shadow cast and the view of the heavenly body i.e. sun or the moon being blocked in the shadow from the earth’s surface. It is either solar eclipse (sun's view blocked) or lunar eclipse (moon's view blocked)


*         Solar Eclipse

The earth orbits the sun and moon orbits the earth. While on their respective paths, it so happens that moon comes in between the sun and the earth. It then blocks the light of the sun and cast a shadow on the earth. People in the shadow area, can't see the sun. Solar eclipse occurs only on a new moon when the sun, moon and earth are in a line. There are two types of solar eclipse depending on the amount of shadow formed and the view of the sun blocked/total solar eclipse and partial solar eclipse.

                     Solar Eclipse  


*         Total Solar Eclipse

Total solar eclipse occurs when the dark shadow of the moon completely blocks the intense sun. Total solar eclipses are very rare celestial phenomenon. During a total solar eclipse, sun seems to disappear during the day and the sky darkens in a few minutes. Total solar eclipse also depends on the position of moon and the earth in its specific orbit. An eclipse that occurs when the moon is near its closest distance to the earth and the earth approaches its farthest distance from the sun, is a total solar eclipse. Because the moon will then appear to be large enough to cover completely the sun's bright side in its shadow. Total solar eclipses are beautiful celestial events, which can never be more than for a few minutes. In a year five to seven solar eclipses occur. No more than two eclipses happen to be a total solar eclipse.

Total solar Eclipse  


*         Partial Solar Eclipse

The other type of eclipse is called the partial solar eclipse. Can you guess anything from the name? Yes, it is only a portion and not the complete thing itself. Partial solar eclipse occurs when a small or big portion, but never the complete, view of the sun is blocked by the moon's shadow. It simply means partial blocking of the sun's view by the moons shadow. Partial solar eclipse is usually seen from a large part of the earth. Occurrence of partial solar eclipse in a year can range from four to five.

Partial Solar Eclipse


Looking directly at the sun, at any timer can cause damage to our eyes. We don't feel like watching the bright and hot sun on any normal day. On the days of eclipse sun looks tempting and we all feel like watching it. But we should never watch a solar eclipse directly. Looking at the sun during an eclipse is dangerous. Looking at the sun, even for a few seconds, can cause permanent damage to our eyes. Viewing the sun through any kind of optical aid like a binoculars, telescopes or even an optical camera is extremely hazardous. Viewing a totally eclipsed sun is not as dangerous as partial eclipsed. Only certified, properly designed solar filters should be used for direct viewing of the sun, during an eclipse.


*       Lunar Eclipse

A lunar eclipse occurs when the earth, the sun and the moon happens to come into a line and earth is between the sun and the moon. The earth casts a large shadow on the moon. Moon loses its brightness and becomes barely visible. Lunar eclipse always takes place on a full moon night. The type of eclipse and the length or duration of eclipse depends upon the moon location. Lunar eclipse may be viewed from anywhere on the night side of the earth. A lunar eclipse lasts for several hours. When the eclipse ends the moon returns to its natural brilliance. Duration of lunar eclipse is for a few hours, depending upon the portion of the moon in the earth's shadow. There are two types of lunar eclipse i.e. total lunar eclipse and the partial lunar eclipse.

                    Lunar Eclipse  


*         Partial Lunar Eclipse

Partial lunar eclipse occurs when little, some or most part of the moon but never the complete or full moon is in the earths shadow. Eclipsed moon is no more bright as it use to be, instead it appears to be darkened on the place which is in the earths shadow.

Partial Lunar Eclipse  


*       Total Lunar Eclipse

Total lunar eclipse occurs when the entire or the complete moon passes through the earth's shadow. These eclipses are spectacular to look at, due to the striking vibrant red colour of moon. A total lunar eclipse lasts for a few hours. The total time between the moons first and the last contact with the shadow is much longer and could last up to three to eight hours. Duration of total lunar eclipse at a given place on earth is only a few minutes. Eclipse duration is affected by the relative distance of the moon from the earth at the time of the eclipse.

Total Lunar Eclipse


The duration of the total lunar eclipse depends on the moon's speed through the earth's shadow. Number of eclipse in a year varies from zero to three. 1982 was a year when three total lunar eclipses occurred in a single calendar year. On 21st December this year we with be given a chance again by the earth, the moon and the sun to watch the spectacular total lunar eclipse.  Lunar eclipses are completely safe to watch. There is no need of any protective filters. We can use Binoculars to magnify the view.





     Solar eclipse occurs when the sun, the earth and ________ is in a straight line

(a) Mercenary

(b) Moon

(c) Venus

(d) Titan

(e) None of the above


Answer: (b)


It is the moon, which cast a shadow on the earth by blocking the sun.

Moon comes between the sun and the earth.



     The natural phenomenon, when Earth cast its shadow on Moon, is known as.

(a) Solar eclipse

(b) Lunar eclipse

(c) Mars eclipse

(d) All of these

(e) None of these


Answer: (b)


The phenomenon, when Earth casts its shadow on Moon, is known as lunar eclipses..

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