Why is it Dark at Night

Why is it Dark at Night

Assessment

Interactive Video

Physics, Science

11th Grade - University

Hard

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The video explores why the night sky is dark despite the universe being filled with stars. It explains that the sky appears blue during the day due to atmospheric scattering of sunlight. In an infinite universe, the sky should be bright, but the universe has a temporal beginning, limiting the light reaching us. Cosmic background radiation from the Big Bang is present, but the expansion of the universe causes redshift, moving light out of the visible spectrum. Thus, the night sky appears dark because distant light is redshifted beyond human vision.

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2 questions

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1.

OPEN ENDED QUESTION

3 mins • 1 pt

What is the relationship between the light from distant stars and the time it takes to reach us?

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2.

OPEN ENDED QUESTION

3 mins • 1 pt

Explain the significance of cosmic background radiation in understanding the night sky.

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