Hinglish

Eclipses

Class 7 Science · Chapter 12: Earth, Moon, and the Sun · NCERT Curiosity section 12.3

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Zoya holds up her thumb at arm's length and closes one eye: it completely hides Neel's head 5 m away! An object's apparent size depends on its real size and its distance. The Moon is about 400 times smaller than the Sun but also about 400 times closer, so both look about the same size in our sky. Venus, though bigger than the Moon, is so far away that it looks like a tiny dot when it crosses the Sun.

When the Moon comes between the Sun and the Earth, its shadow falls on a small patch of Earth: a solar eclipse. Inside that patch the Sun is fully hidden for a few minutes (total); nearby, only part of it is covered (partial). As the Moon moves on, a bright "diamond ring" can flash. Never look at the Sun directly, not even during an eclipse or through sunglasses or binoculars: join a planetarium or astronomy club viewing with proper filters, or project the Sun's image.

When the Earth comes between the Sun and the Moon, the Earth's shadow falls on the full Moon: a lunar eclipse. In a total lunar eclipse the Moon turns dark red; in a partial one, only part is shadowed. It is safe to watch with the naked eye. Eclipses (grahan) were once feared, but Indian astronomers like those of the Surya Siddhanta calculated them in advance; today scientists travel the world to study them. India's Kodaikanal Solar Observatory has watched the Sun since 1899, and M. K. Vainu Bappu is called the father of modern Indian astronomy.

Explore: solar or lunar eclipse?

  1. Sort each feature.

Remember

  • Solar eclipse: Moon between Sun and Earth; never look directly at the Sun.
  • Lunar eclipse: Earth between Sun and Moon; the Moon can turn red and is safe to watch.

Quick check

During which eclipse is the Moon between the Sun and the Earth?

  1. solar eclipse
  2. lunar eclipse
  3. both
  4. neither
Answer

solar eclipse. In a lunar eclipse the Earth is in the middle.

Think about it

Why don't we have a solar eclipse every new moon?

One answer

The Moon's orbit is slightly tilted compared with the Earth's, so most months the Moon passes a little above or below the line joining the Sun and the Earth.

Practice

Practise with fresh questions at three levels (easy, medium, hard), some answered hands-on, with hints and worked answers. Get 4 of your last 5 right to finish the topic.