Hourwiz Explains · video notes

If Earth Was a Grain of Sand, How Big Would the Universe Be?

From the Hourwiz video “If Earth was a grain of sand…” · Checked Oct 14, 2026

Watch on YouTube (opens in a new tab)Instagram (opens in a new tab)Facebook (opens in a new tab)

Our method: we shrank Earth's 12,742 km diameter to a 1 mm coarse grain of sand, a scale of 1 : 12.74 billion, and divided every bigger thing below by that same factor.

Our scale model. One fixed factor, never changed: real size ÷ 12,742 km per millimeter. A small Node script did the arithmetic on Oct 14, 2026, and it matched our hand calculation at the rounding shown. Every size is a diameter, except the Pillars of Creation, which is a height.

Why a 1 mm grain: the US Geological Survey's sand chart puts “coarse” sand at 0.5–1 mm and “very coarse” at 1–2 mm, so 1 mm is a coarse grain.

The 14 steps

Our scale model · Earth = 1 mm
Object	Real size	At grain scale	Everyday comparison	× previous
Earth	12,742 km across (about 7,918 mi)	1 mm	a coarse grain of sand	start
Jupiter	139,822 km across	11 mm (under ½ inch)	11 grains wide	×10.97
The Sun	1,391,400 km across (about 109 Earths)	4.3 in (11 cm)	a bit bigger than a softball	×9.95
Arcturus, a giant star	25.4 times the Sun's width	9.1 ft (2.8 m)	almost as tall as a basketball hoop (10 ft)	×25.4
Betelgeuse, a red supergiant	about 764 times the Sun's width	about 274 ft (91 yd)	about a football field, goal line to goal line	×30.1
Neptune's orbit	about 9.03 billion km across	0.44 mi (709 m)	almost half a mile wide	×8.49
Pillars of Creation, in the Eagle Nebula	about 5 light-years tall	about 2,300 mi (3,700 km) tall	taller than the real Moon is wide	×5,239
Orion Nebula	estimates disagree*	more than 7,900 mi	wider than the real Earth	×8*
Tarantula Nebula	nearly 1,000 light-years across	about 461,000 mi (742,000 km)	almost twice the real Earth–Moon distance	×25*
The Milky Way	about 100,000 light-years across	about 46 million mi (74 million km)	about half the real Earth–Sun distance	×100
Andromeda galaxy	about 260,000 light-years across	about 120 million mi (193 million km)	wider than the real Earth–Sun distance	×2.6
Local Group, our galaxy's neighborhood	nearly 10 million light-years across	about 50 times the Earth–Sun distance	almost as wide as Neptune's real orbit	×38.5
Laniakea, our supercluster	about 500 million light-years across	about 0.04 light-year (about 14 light-days)	light would need about two weeks to cross it	×50
The universe we can see	about 93 billion light-years across	about 7.3 light-years	still light-years wide: wider than the real gap to the nearest star (4.2 light-years)	×186

Our take: shrinking Earth didn't make space feel small. It made it worse.

The biggest jump: Neptune's orbit to the Pillars of Creation, ×5,239. At that zoom, the planets' whole racetrack is a dot.
* Orion: published sizes for the Orion Nebula disagree, because it depends on where you draw its edge. So we only say “wider than the real Earth”, which holds for every size we found. The ×8 and ×25 around it depend on that choice.
The universe we can see is the observable part. Nobody knows how big the whole universe is.
“About” matters: the sizes of galaxies, superclusters and the observable universe are estimates. A slightly different estimate moves our numbers a little (the universe comes out at 7.2–7.4 light-years), not the story.
The pictures: no photo of the whole Milky Way from outside exists. The face-on Milky Way in the video is an artist's concept.

Download the scale model

Every step with its source row, real size in km, the ratio to the step before, and the model size in mm, inches, feet, meters, km, miles, au and light-years.

Download the scale model (.csv)

Images in the video

Earth: NASA Earth Observatory (Blue Marble Next Generation) and NASA Goddard (cloud map)
Jupiter: NASA/JPL/Space Science Institute
Pillars of Creation: NASA, ESA/Hubble and the Hubble Heritage Team (CC BY 4.0, cropped by Hourwiz)
Orion Nebula: NASA, ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team (CC BY 4.0, cropped by Hourwiz)
Tarantula Nebula: NASA, ESA, CSA, and STScI (CC BY 4.0, cropped by Hourwiz)
Milky Way, artist's concept: NASA/JPL-Caltech
Andromeda galaxy: Courtesy NASA/JPL-Caltech
Webb's First Deep Field: NASA, ESA, CSA, and STScI (CC BY 4.0, cropped by Hourwiz)

The stars, Neptune's orbit, the Local Group and Laniakea are drawn by Hourwiz as illustrations.

Sources

Every fact on this page comes from these pages, opened on Oct 14, 2026. Things change: check the live page before you rely on it.

USGS, grain-size chart (after Wentworth, 1922) Coarse sand 0.5–1 mm, very coarse 1–2 mm.
NASA NSSDC, Earth fact sheet Mean radius 6,371 km, so 12,742 km across.
NASA NSSDC, Jupiter fact sheet Mean radius 69,911 km.
NASA NSSDC, Sun fact sheet Mean radius 695,700 km, 109.2 Earths.
NASA NSSDC, Neptune fact sheet Average distance from the Sun 4,514.953 million km.
NASA NSSDC, Moon fact sheet Diameter 3,474.8 km, average distance 384,400 km.
IAU, measuring the universe The au and the light-year.
Ramírez & Allende Prieto, ApJ 743, 135 (2011): Arcturus R = 25.4 Sun radii.
Joyce et al., ApJ 902, 63 (2020): Betelgeuse A red supergiant; radius 764 (+116/−62) Sun radii.
NASA, Hubble revisits the Pillars of Creation (Jan 5, 2015) About 5 light-years high; part of the Eagle Nebula.
NASA APOD, Orion Nebula (Jul 13, 2004) The size we used for the zoom ratio.
ESO, the Tarantula Nebula Nearly 1,000 light-years across.
NASA Goddard, Imagine the Universe: the Milky Way About 100,000 light-years across.
NASA/JPL Photojournal, Andromeda (PIA15416) Spans 260,000 light-years.
NASA Goddard, Imagine the Universe: the Local Group Nearly 10 million light-years across.
University of Hawaiʻi, Laniakea (Sept 3, 2014) 500 million light-years in diameter.
Egan & Lineweaver, ApJ 710, 1825 (2010): the observable universe Radius 46.9 billion light-years.
Caltech IPAC Cool Cosmos, how big is the universe? About 92 billion light-years; nobody knows the whole universe's size.
ESO, Proxima Centauri (eso1629) The closest star after the Sun.
Kervella, Thévenin & Lovis, A&A 598, L7 (2017): Proxima's distance 1.3008 pc, about 4.24 light-years.
NCAA softball rules book 12-inch class ball: about 3.8 in across.
NBA Rule No. 1, court dimensions The ring is 10 ft above the floor.
NFL rulebook (2024) 100 yards goal line to goal line.
NIST, unit conversions Exact foot and mile.
NIST CODATA, speed of light For the light-days.

Our scale model: one factor (Earth = 1 mm), rounded as shown. Space agencies' images and data are credited above; NASA, ESA, CSA, ESO and JPL didn't make, review or endorse this page or the video.

No sponsor and no affiliate links on this page. Vendors are named so you can check them yourself, not as recommendations.

Follow Hourwiz

All video pages Back to Hourwiz home