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New to astronomy? We explain every term as you browse, in plain English. Same pages, with the help built in.

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The Scale of the Universe

From your own height to the edge of everything we can see: 26 powers of ten. Slide, scroll, and feel it.

You 100 m
100 meters You

A human being, our unit of wonder.

104 meters A city

About 20 km across. Walkable in a day.

107 meters Earth

12,742 km wide. Every person who ever lived, on one rock.

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109 meters Earth–Moon

384,400 km. All the other planets could line up in the gap.

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109 meters The Sun

1.39 million km wide, or 109 Earths across.

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1011 meters Earth–Sun

1 astronomical unit: 8 minutes at light speed.

1013 meters The Solar System

Out to Neptune and the Kuiper Belt, past 30 AU.

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1013 meters Voyager 1

The farthest human-made object: 25 billion km in 48 years.

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1016 meters The Oort Cloud

The Sun's comet shell, reaching perhaps a light-year out.

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1017 meters Proxima Centauri

The nearest star: 4.25 light-years.

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1018 meters Stellar neighborhood

A hundred light-years: everything you can name in the night sky lives here.

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1021 meters The Milky Way

100,000 light-years, 100–400 billion stars.

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1023 meters The Local Group

10 million light-years: our galaxy cluster of ~80 members.

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1025 meters The cosmic web

500 million light-years: galaxies string into filaments and voids.

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1027 meters The observable universe

93 billion light-years across. Beyond it: more universe, unseen.

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A trick for impossible numbers: each step above is not “a bit bigger”. Most are a thousand to a million times bigger than the last. Human intuition tops out around the city step; past that, only ratios and comparisons carry meaning. That is why this site always translates: light-time, driving-time, basketballs and peppercorns.