Neil deGrasse Tyson Explains the REAL Length of Day

StarTalk2 minutes read

Earth's rotation lasts 23 hours, 56 minutes, and 4 seconds, causing variations in solar day length. Leap seconds are added to maintain a consistent 24-hour day to account for Earth's orbit and tidal influences.

Insights

  • Earth's rotation takes 23 hours, 56 minutes, and 4 seconds, not a full 24 hours, impacting our daily lives structured around the solar day.
  • Variations in Earth's rotation, influenced by factors like tides and mass distribution changes, necessitate the addition of leap seconds to maintain a consistent 24-hour day, showcasing the meticulous management of time and the scientific complexities involved.

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Recent questions

  • How long does it take for Earth to rotate on its axis?

    Earth takes 23 hours, 56 minutes, and 4 seconds to rotate on its axis, not the commonly known 24 hours.

  • What causes variations in the length of a solar day throughout the year?

    Earth's orbit not being a perfect circle causes variations in the length of a solar day throughout the year.

  • How do tides on the ocean floor influence Earth's rotation?

    Tides on the ocean floor, influenced by the moon, slow down Earth's rotation.

  • How are leap seconds added to maintain a consistent 24-hour day?

    Leap seconds are added internationally when Earth's rotation falls behind, occurring on June 30th or December 31st.

  • How can mass distribution affect Earth's rotation speed?

    Skaters' movements illustrate how changing mass distribution can alter rotation speed.

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Summary

00:00

"Earth's Rotation: Timekeeping Complexity Unveiled"

  • Earth takes 23 hours, 56 minutes, and 4 seconds to rotate on its axis, not the commonly known 24 hours.
  • This duration is known as a sidereal day, based on the stars' positions, but our daily lives are structured around the solar day, which accounts for Earth's orbit around the sun.
  • Earth's orbit is not a perfect circle, causing variations in the length of a solar day throughout the year.
  • Tides on the ocean floor, influenced by the moon, slow down Earth's rotation, leading to the moon moving away from us by a few inches annually.
  • To maintain a consistent 24-hour day, leap seconds are added internationally when Earth's rotation falls behind, occurring on June 30th or December 31st.
  • The rotation of Earth can be affected by factors like tidal sloshing, animal migrations, earthquakes, and melting land glaciers.
  • Skaters' movements illustrate how changing mass distribution can alter rotation speed, similar to how Earth's rotation can be affected by continental shifts or volcanic activity.
  • Despite theoretical ideas like using jet engines to alter Earth's rotation, the planet's immense mass renders such attempts ineffective.
  • The meticulous management of time, including the introduction of leap seconds, ensures the accuracy of our clocks and schedules.
  • The complexities of Earth's rotation highlight the intricate scientific considerations that underpin our everyday timekeeping systems.

16:07

"Countdown to Leap Second Celebration"

  • Mention of preparing for the next leap second
  • Suggestion of a special show to celebrate a leap second with an atomic clock
  • Reminder to have champagne for the celebration
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