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DD-131Spacealso ScienceFiled Last updated

Earth

Short answer: Earth is not a perfect sphere but an oblate spheroid: its rotation flattens it at the poles and makes it bulge at the equator. The equatorial diameter is about 43 km greater than the polar diameter.

Because of the bulge, the point on Earth's surface farthest from its center is the summit of Chimborazo in Ecuador, not Everest. The footage shows Earth from space, with the presenter.

VideoWrite-up2 sources
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What should you know about Earth?

Quick facts. Each one stands alone and has a stable ID you can cite.

  1. Earth is an oblate spheroid.

    DD-131-F01 · Write-up · Exhibit A (Oblate spheroid)

  2. Its rotation causes the bulge.

    DD-131-F02 · Write-up · Exhibit B (Rotation)

Video transcript: Earth: Earth Is About 43 km Wider Than It Is Tall

Earth our home planet is not a perfect sphere. DID YOU KNOW? It's slightly flattened at the poles and bulging at the equator due to its rotation. This shape is known as an oblate spheroid, the equatorial diameter is larger the diameter measured from pole to pole. This phenomenon results from the Earth's rotation causing a slight outward force at the equator and making it not a perfect sphere. This subtle distortion in shape is a fascinating aspect of our planet's NOW YOU KNOW!

Burned-in captions, read frame by frame (see transcript.md) · 23.9s Reel ·

Video coming soonEarth · Instagram Reel
Earth: Earth Is About 43 km Wider Than It Is Tall Instagram Reel · · 23.9s

The write-up

Earth is about 43 km wider than it is tall. Its spin flattens it into an oblate spheroid.

  1. Exhibit A

    Oblate spheroid

    Earth is an oblate spheroid.

  2. Exhibit B

    Rotation

    Its rotation causes the bulge.

  3. Exhibit C

    43 km

    The equatorial diameter is about 43 km greater.

  4. Exhibit D

    Chimborazo

    Chimborazo's summit is farthest from Earth's center.

  5. Exhibit E

    Not a sphere

    The flattening is slight, about 0.3%.

Questions people ask about Earth

What shape is Earth?

Flattened at the poles.

Source: Write-up · Exhibit A (Oblate spheroid) · Wikipedia: Earth; Wikipedia: Equatorial bulge

What causes the bulge?

Spin pushes the equator out.

Source: Write-up · Exhibit B (Rotation) · Wikipedia: Equatorial bulge

How much wider is Earth at the equator?

Diameter difference.

Source: Write-up · Exhibit C (43 km) · Wikipedia: Equatorial bulge

Which summit is farthest from Earth's center?

Thanks to the bulge.

Source: Write-up · Exhibit D (Chimborazo) · Wikipedia: Equatorial bulge

How big is the flattening?

Slight.

Source: Write-up · Exhibit E (Not a sphere) · Wikipedia: Equatorial bulge

Test Your Knowledge

All quizzes →

5 questions, all from this case file. Answers are revealed instantly.

  1. What shape is Earth?

    1. An oblate spheroid
    2. A perfect sphere
    3. A cube
    4. A cylinder
    Show the answer

    Answer: A. An oblate spheroid Flattened at the poles. Source: Write-up · Exhibit A (Oblate spheroid) · Wikipedia: Earth; Wikipedia: Equatorial bulge

  2. What causes the bulge?

    1. Rotation
    2. The Moon only
    3. Volcanoes
    4. Oceans
    Show the answer

    Answer: A. Rotation Spin pushes the equator out. Source: Write-up · Exhibit B (Rotation) · Wikipedia: Equatorial bulge

  3. How much wider is Earth at the equator?

    1. About 43 km
    2. About 4 m
    3. About 4,300 km
    4. Not at all
    Show the answer

    Answer: A. About 43 km Diameter difference. Source: Write-up · Exhibit C (43 km) · Wikipedia: Equatorial bulge

  4. Which summit is farthest from Earth's center?

    1. Chimborazo
    2. Everest
    3. Kilimanjaro
    4. Mont Blanc
    Show the answer

    Answer: A. Chimborazo Thanks to the bulge. Source: Write-up · Exhibit D (Chimborazo) · Wikipedia: Equatorial bulge

  5. How big is the flattening?

    1. About 0.3%
    2. About 30%
    3. About 3%
    4. Zero
    Show the answer

    Answer: A. About 0.3% Slight. Source: Write-up · Exhibit E (Not a sphere) · Wikipedia: Equatorial bulge

Cite this case file

Easterling, Marcus. "Earth." The Detail Department (DetailEnjoyer), case file DD-131, last updated Dec 20, 2023. https://detailenjoyer.com/case/earth/

Permalink: https://detailenjoyer.com/case/earth/ · Last updated

Markdown version

Cite a single fact by its ID, for example DD-131-F01 → https://detailenjoyer.com/case/earth/#DD-131-F01