From: How Big Is Big? Exploring Size from Atoms to Galaxies
evidenceobservational

The Milky Way galaxy is about 100,000 light-years across.

95% confidence

Our galaxy, the Milky Way, is enormous compared to Earth. It stretches about 100,000 light-years, meaning light takes 100,000 years to travel from one side to the other. Since light travels about 300,000 kilometers every second, this distance is almost impossible to picture. The galaxy contains billions of stars, planets, and other objects, making it one huge cosmic city.

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4 perspectives4 visualizations4 insights11 media resources7 rabbit holes
evidence
Atoms are incredibly small, about one ten-billionth of a meter across.
evidence
The observable universe is about 93 billion light-years wide.
evidence
The Earth is about 12,742 kilometers (7,918 miles) wide.
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How Big Is Big? Exploring Size from Atoms to Galaxies
Evidence, perspectives, rabbit holes, and more