Size comparison of planets, stars and the universe

How big is Earth compared to the Sun, and the Sun compared to the largest known stars? Here you see everything side by side at true scale: from a neutron star (about 20 km) through the Moon, planets and stars up to the observable universe. Drag, use the mouse wheel or the slider to zoom smoothly; in “Compare” mode you put any two objects directly against each other.

Interactive size comparison

Diameters at a glance

ObjectDiameterCompared to Earth
Neutron star≈ 20 km0.00157×
Moon3,475 km0.273×
Mercury4,879 km0.383×
Mars6,779 km0.532×
Venus12,104 km0.95×
Earth12,742 km1×
Neptune49,244 km3.86×
Uranus50,724 km3.98×
Saturn116,460 km9.14×
Jupiter139,820 km11×
Sun1,392,700 km109×
Sirius A2,383,000 km187×
Betelgeuse≈ 1,060,000,000 km83,200×
UY Scuti≈ 1,270,000,000 km99,700×
Stephenson 2-18≈ 2,990,000,000 km235,000×
Sagittarius A*25,400,000 km1,990×

Real diameters, rounded. For giant stars the values are estimates and differ between measurements. For black holes the diameter of the event horizon is shown.

Frequently asked questions

How big is Earth compared to the Sun?

The Sun's diameter is about 109 times Earth's. By volume, roughly 1.3 million Earths would fit inside the Sun.

Which planet is the biggest?

Jupiter is the largest planet in the Solar System. Its diameter is about 139,820 km, roughly 11 times that of Earth.

What is the biggest known star?

Stephenson 2-18 is among the largest known stars, with an estimated diameter of around 3 billion kilometres. Such values are estimates and are revised again and again.

How does the size comparison work?

All objects are drawn at the same scale, from a neutron star to the observable universe. Drag, use the mouse wheel or the slider to zoom from one object to the next; “Compare” mode shows the exact size ratio of two objects.