Eclipses: Crash Course Astronomy #5

CrashCourse11 minutes read

The Sun and Moon look the same size in the sky because the Sun is much bigger but also much farther away. Solar eclipses are caused by the Moon blocking the Sun, while lunar eclipses happen when the Earth blocks the Sun from reaching the Moon.

Insights

  • The Sun and Moon appear the same size in the sky because the Sun is 400 times wider than the Moon and also 400 times farther away, creating an optical illusion.
  • Lunar eclipses, caused by the Earth blocking the Sun's light from reaching the Moon, are safe to view and can last nearly two hours, offering a unique celestial spectacle visible from anywhere facing the Moon.

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Recent questions

  • Why does the Sun and Moon appear the same size?

    Due to the Sun being 400 times wider than the Moon and 400 times farther away.

  • What causes a solar eclipse?

    A solar eclipse occurs when the Moon blocks the Sun.

  • How long does a total solar eclipse last?

    Total solar eclipses are brief, lasting about seven to eight minutes.

  • Why do lunar eclipses appear red?

    The Earth's umbral and penumbral shadows cause the Moon to darken and sometimes turn red during a lunar eclipse.

  • Can you view a solar eclipse without eye protection?

    Viewing a solar eclipse without proper eye protection can lead to retinal damage.

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Summary

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"Sun and Moon: Eclipses and Shadows"

  • The Sun and Moon appear to be the same size in the sky due to the Sun being 400 times wider than the Moon and 400 times farther away.
  • A solar eclipse occurs when the Moon blocks the Sun, casting a shadow on the Earth, while a lunar eclipse happens when the Earth blocks the Sun, casting a shadow on the Moon.
  • The Moon's orbit being tilted by about 5° with respect to Earth's prevents solar and lunar eclipses from happening every new and full Moon.
  • During a solar eclipse, the Moon casts two shadows on Earth - the umbra, where the Sun is completely blocked, and the penumbra, where the Sun is partially blocked.
  • Total solar eclipses are brief, lasting about seven to eight minutes, with the Diamond Ring effect occurring as the Moon moves off the Sun's face.
  • Viewing a solar eclipse without proper eye protection can lead to retinal damage due to the intense sunlight, especially during the flash of sunlight after totality ends.
  • Lunar eclipses are safe to view as the Earth's shadow falls on the Moon, and they can be seen from anywhere on Earth facing the Moon.
  • The Earth's umbral and penumbral shadows cause the Moon to darken and sometimes turn red during a lunar eclipse, with the eclipse lasting nearly two hours.
  • Lunar eclipses have been historically used to estimate the relative sizes of the Earth and Moon, showcasing the ancient Greeks' understanding of geometry and celestial bodies.
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