The story of diameter

Chapter 1

The math of the middle

Chapter 2

Sizing up the cosmos

Chapter 3

Engineering the everyday

YOUR GOAL

Master of The story of diameter

Ch 2 · Sizing up the cosmos

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hue Cosmic Diameters

Our diameter is ninety-three billion light-years, and space is still stretching out!

Jul 20

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hue The giant waistline of Earth

Jul 20

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hue The moon's apparent size, known as its angular diameter, remains constant despite looking larger near the horizon.

Jul 20

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hue Astronomers calculate the physical diameter of distant stars by measuring their brightness and temperature.

Jul 20

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BETA

hue Sort cosmic objects by diameter to discover the true scale of the universe.

Jul 20

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Fun Fact

Cosmic scale: The Sun's diameter is so massive that about 109 Earths could fit lined up side-by-side across its face.

Jul 20

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Gossip

Which planet would you most want to visit if size didn't matter?

Jul 20

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Quiz

In 2019, scientists imaged the shadow of a black hole in which galaxy to find its diameter?

Jul 20

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hue How we weigh the stars

Jul 20

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Quiz

What physical property of a star must astronomers combine with temperature to calculate its diameter?

Jul 20

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hue Measuring black holes by their shadows

Jul 20

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Quiz

What term do astronomers use to describe how big an object looks in the night sky?

Jul 20

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hue The moon illusion in the sky

Jul 20

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Quiz

What is the approximate equatorial diameter of planet Earth?

Jul 20

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Quiz

Which planet in our solar system has the largest physical diameter?

Jul 20

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Quiz

What is the angular diameter of both the Sun and the Moon as seen from Earth?

Jul 20

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Quiz

Why is Earth's equatorial diameter larger than its polar diameter?

Jul 20

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Quiz

Approximately how many Earths could fit side-by-side across the diameter of the Sun?

Jul 20