Physics
Answer
As the sun is bigger in size than the earth and the earth is bigger in size than the moon so when the sun, the earth and the moon come in a straight line, the earth or the moon whichever comes in between, casts its shadow on the other and causes an eclipse.
Two types of eclipses are :
- Lunar eclipse
- Solar eclipse
Related Questions
Why is it that the birds flying in the sky do not cast their shadows on the earth ?
Why are shadows at noon shorter than in the morning or in the evening?
When does a lunar eclipse take place ? Does it occur on every full moon's night?
When does a solar eclipse take place ? Does it occur on every new moon's day?