Light seconds, light years, light centuries: How to measure extreme distances - Yuan-Sen Ting

TED-Ed2 minutes read

Light, the fastest entity known, measures distances by its travel time, such as a light year being 6 trillion miles and the Moon one light-second away. Astrophysicists use parallax and standard candles like cepheid variables and type 1a supernovae to determine the distances of stars and galaxies, helping decode the universe's history and our origins.

Insights

  • Light travels at an incredible speed, allowing us to measure distances in light years, revealing the vastness of space. The use of standard candles like cepheid variables and type 1a supernovae helps astrophysicists determine distances to stars and galaxies, providing crucial insights into the universe's history and our origins.
  • By observing distant objects and decoding the information carried by light, astrophysicists can look back in time, unraveling the mysteries of the universe's past. This process not only aids in understanding cosmic history but also sheds light on our own origins, offering a glimpse into the fundamental nature of our existence.

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Recent questions

  • How is the distance of stars measured?

    Using trigonometric parallax for nearby objects and standard candles for farther ones.

  • What aids in determining the luminosity of stars?

    Brightness variation of cepheid variables and characteristics of type 1a supernovae.

  • How does observing distant objects help in understanding the universe's history?

    By looking back in time due to light's travel duration.

  • What is the significance of a light year?

    It measures distance based on light's travel time.

  • How does the Moon's distance from Earth compare to light travel time?

    The Moon is only one light-second away.

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Summary

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Decoding Light: Unveiling Universe's History

  • Light is the fastest known entity, with distances measured by its travel time. A light year is about 6,000,000,000,000 miles, with the Moon only one light-second away from Earth.
  • To determine the distance of stars and galaxies, astrophysicists use trigonometric parallax for nearby objects. For farther ones, standard candles like cepheid variables and type 1a supernovae are employed.
  • Cepheid variables' brightness variation helps calculate their luminosity, aiding in determining their distance. Type 1a supernovae, due to their brightness and fade rate, serve as standard candles for distances up to billions of light years.
  • Observing distant objects allows us to look back in time due to the light's travel duration. This aids astrophysicists in understanding the universe's history and our origins by decoding the information sent through light.
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