Compare objects across the universe

The Moon looks large in our sky because it is close. By diameter, Earth is much larger, although its companion is unusually substantial relative to its planet.

Jupiter is the Solar System’s largest planet; its diameter is about eleven Earth diameters.

The Sun spans about 109 Earth diameters and contains more than 99.8% of the Solar System’s mass.

Betelgeuse is a red supergiant with an approximate photospheric diameter hundreds of times the Sun’s.

A hydrogen atom consists of a proton and an electron, yet its characteristic atomic diameter is about 60,000 times the proton’s.

A water molecule’s maximum extent is about 2.7 times the characteristic diameter used here for a hydrogen atom.

M87* is thousands of times more massive than the Milky Way’s central black hole, so its event-horizon diameter is about 1,550 times larger in this dataset.

The bright structure of the Helix Nebula spans a little more than twice the diameter used here for the Ring Nebula.

Earth is about 1.9 times Mars's diameter. Both planets have seasons, polar caps and weather, but Mars has only a thin atmosphere.

Earth and Venus are the closest size match among the major planets: Earth is only about 5% wider.

Earth is about 2.6 times Mercury's diameter; Mercury is the smallest of the eight major planets.

Saturn itself—not including its rings—is about 9.1 times Earth’s diameter.

Uranus is about four Earth diameters wide, slightly larger than Neptune and far larger than any rocky planet.

Neptune is about 3.9 times Earth's diameter, only slightly smaller than Uranus despite their different appearances.

Earth is about 5.4 times Pluto’s diameter. Pluto is smaller than several moons, but it remains a geologically varied world.

Jupiter is about 20% wider than Saturn, the other hydrogen-helium giant, and more than three times as massive.

Jupiter is about 2.8 times Uranus’s diameter, separating the largest gas giant from the smaller ice giants.

Jupiter is about 2.8 times Neptune’s diameter, comparing the largest gas giant with an ice giant.

Mars is almost twice the Moon’s diameter. The labels “planet” and “moon” describe orbital roles, not fixed size classes.

The Moon is about 1.5 times Pluto’s diameter. Their different classifications reflect their orbits, not a simple size threshold.

Mercury is about 2.1 times Pluto’s diameter. It is the smallest major planet, while Pluto is a dwarf planet.

Andromeda’s quoted visible diameter is about 1.5 times the Milky Way’s stellar-disk diameter.

The Large Magellanic Cloud’s quoted diameter is about 1.7 times that of the Small Magellanic Cloud.

Sirius A is a main-sequence star about 1.7 times the Sun’s diameter.

The Sun is about 6.5 times the diameter of Proxima Centauri, the nearest known star beyond it.

The Sun is about 123 times the diameter of Sirius B, a white dwarf with roughly one solar mass.

Rigel is a hot blue supergiant about 74 times the Sun’s diameter.

Deneb’s quoted diameter is about 200 times the Sun’s, although its uncertain distance limits the precision of the estimate.

Arcturus is an orange giant about 25 times the Sun’s diameter.

Aldebaran is a red-giant-branch star about 45 times the Sun’s diameter.

Pollux is an orange giant about nine times the Sun’s diameter.

Polaris Aa, the dominant star in the North Star system, is about 46 times the Sun’s diameter.

VY Canis Majoris has a quoted diameter about 1,400 times the Sun’s, but its extended atmosphere has no sharp edge.

Stephenson 2 DFK 49 has a quoted diameter about 1,150 times the Sun’s, with substantial uncertainty in the star’s distance and photospheric edge.

Betelgeuse’s quoted photospheric diameter is about ten times Rigel’s, although both stars have extended atmospheres.

VY Canis Majoris’s quoted visible extent is about 1.9 times Betelgeuse’s approximate photospheric diameter.

Stephenson 2 DFK 49’s quoted extent is about 1.5 times Betelgeuse’s approximate photospheric diameter.

Sirius A is about 211 times the diameter of its white-dwarf companion, Sirius B.