Universe: Quick Facts

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The Information Architects of Encyclopaedia Britannica

Last updated

Nov. 12, 2026

News •

How did the universe take shape? A new simulation offer clues • Nov. 11, 2026, 8:30 AM ET (CNN)

A distant exoplanet mysteriously vanished from sight. Astronomers just discovered why • Nov. 10, 2026, 4:00 PM ET (Space)

Theory predicting an older universe without dark matter or dark energy passes key cosmological tests • Nov. 7, 2026, 9:00 AM ET (Phys.org)

Colliding Stars in Early Universe May Explain Stellar Monsters, Study Suggests • Nov. 3, 2026, 6:12 PM ET (Sci.News)

What ended the 'Cosmic Dark Age'? Astronomers say they're closer than ever to an answer. • Oct. 31, 2026, 11:00 AM ET (Live Science)

Photos and Videos

Diagram illustrating Eratosthenes' method for calculating Earth's circumference, showing the angle of sunlight at Syene and Alexandria, camels traveling between the two cities, and rays from the Sun striking Earth's surface at different angles.

Galileo's telescopes

photosphere of the Sun

Diagram illustrating stellar parallax, showing Earth at two points in its orbit around the Sun, with lines connecting each position to a distant star and forming an angle labeled p to represent the parallax shift.

globular cluster M80

Diagram showing the side view outline of the Milky Way Galaxy with yellow dots representing the distribution of globular star clusters surrounding the galactic disk, and a cross marking the Sun's position.

Pinwheel Galaxy (M101)

The Andromeda Galaxy, a bright spiral galaxy with a glowing core and swirling arms, appears against a dense field of stars in deep space.

Diagram showing types of galaxies in astronomy, including elliptical galaxies labeled E0, E3, and E7, normal spiral galaxies Sa, Sb, and Sc, barred spiral galaxies SBa, SBb, and SBc, and irregular galaxies, each illustrated with characteristic shapes.

Britannica editor Erik Gregersen, a white man wearing glasses, holds a microphone in front of a galaxy background. Displayed above him are the phrases: Ask an Editor, and How old is the universe?

Diagram of the Milky Way galaxy showing labeled locations of the Sun, Milky Way center, Sagittarius dwarf elliptical, and Canis Major dwarf, with axes marking 80,000 light-years.

How did Ptolemy explain retrograde motion?

Aristotle's theory of the solar system explained

Copernicus's revolutionary theory: The Sun as the center

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Topics

Star Eclipse Galaxy Cosmology Sun gravity Solar system Star cluster gravitation space motion chemical element subatomic particle atom Observable universe principles of physical science chemistry time Earth sciences light electromagnetism

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Key People

Democritus

Democritus

Greek philosopher

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James Peebles

American physicist

Fred Hoyle

Sir Fred Hoyle

British mathematician and astronomer

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Pierre-Louis Moreau de Maupertuis

French mathematician and astronomer

Saul Perlmutter

Saul Perlmutter

American physicist

Ursa major constellation illustration art. (Big Dipper) stars, space, night sky)

Stars: Explosions in Space

The orbits of the planets and other elements of the solar system, including asteroids, Kuiper belt, Oort cloud, comet

Space Odyssey

Nicolaus Copernicus. Nicolas Copernicus (1473-1543) Polish astronomer. In 1543 he published, forward proof of a Heliocentric (sun centered) universe. Coloured stipple engraving published London 1802. De revolutionibus orbium coelestium libri vi.

All About Astronomy

View of the Andromeda Galaxy (Messier 31, M31).

Astronomy and Space Quiz

View of the Andromeda Galaxy (Messier 31, M31).

Astronomy and Space Quiz

Nicolaus Copernicus. Nicolas Copernicus (1473-1543) Polish astronomer. In 1543 he published, forward proof of a Heliocentric (sun centered) universe. Coloured stipple engraving published London 1802. De revolutionibus orbium coelestium libri vi.

All About Astronomy