Earth and Moon size comparison, and how both measure up to the Sun

01

Earth to Moon size comparison: how big is the Moon?

The Moon is about 27 percent as wide as Earth. NASA’s Planetary Fact Sheet gives Earth’s equatorial diameter as 7,926 miles (12,756 km) and the Moon’s diameter as 2,159 miles (3,475 km). That means 3.7 Moons would fit side by side across Earth.

By volume the gap is much bigger, because volume grows with the cube of the diameter: 3.67 × 3.67 × 3.67 is about 49.5, so roughly 50 Moons would fill the space of one Earth. Neither body is a perfect sphere, so treat that as a rounded count.

A model you can hold makes it easier. If Earth were a size 7 basketball, 9.5 in (24.2 cm) across under FIBA’s rules, the Moon would be about 2.6 in (6.6 cm) wide, almost exactly a tennis ball, which the ITF sets at 2.57 to 2.70 in (6.54 to 6.86 cm).

02

Mars Earth size comparison, plus Mercury, Pluto and the big moons

Mars is just over half as wide as Earth: 4,220 miles (6,792 km) against 7,926 miles (12,756 km), or 53 percent. By volume that is about 15 percent of Earth, so six and a half Mars would fill one Earth. Mars is also almost exactly twice as wide as the Moon (1.95 times). In the basketball model, Mars would be about 5.1 in (12.9 cm) across.

Mercury, 3,032 miles (4,879 km) wide, sits between the Moon and Mars. Two moons are bigger than Mercury: Jupiter’s Ganymede, the largest moon in the solar system at 3,270 miles (5,262 km), and Saturn’s Titan at 3,200 miles (5,150 km), both from NASA’s satellite fact sheets.

Pluto is smaller than our Moon. NASA gives its equatorial diameter as about 1,477 miles (2,377 km), roughly two thirds of the Moon’s width.

03

Earth sun size comparison: how many Earths fit in the Sun?

About 109 Earths fit across the Sun, and about 1.3 million inside it. NASA’s Sun Fact Sheet gives a volumetric mean radius of 695,700 km (about 432,300 miles), so the Sun is about 864,600 miles (1,391,400 km) across, 109 times Earth’s diameter.

The volume count follows from the cube: 109 × 109 × 109 is about 1.3 million. That is a count by volume; real Earth-sized balls packed into the Sun would leave gaps between them.

In the basketball model, the Sun would be a ball about 87 ft (26.4 m) across, a little shorter than a 92 ft (28 m) FIBA basketball court and roughly as long as a typical blue whale. The Sun is also about 400 times as wide as the Moon. Both look about the same size in our sky only because the Sun is so much farther away.

04

Jupiter sun size comparison

The Sun is nearly 10 times as wide as Jupiter, and Jupiter about 11 times as wide as Earth. NASA gives Jupiter an equatorial diameter of 88,846 miles (142,984 km), measured at the level where the atmospheric pressure is 1 bar, since the planet has no solid surface to measure. So 9.7 Jupiters span the Sun, and 11.2 Earths span Jupiter.

In the basketball model, Jupiter would be about 8 ft 11 in (2.7 m) across, more than 2 ft taller than a standard 6 ft 8 in (2.03 m) US door, while the Sun would be the 87 ft ball from above. Jupiter is the largest planet, yet it is a small body next to its star.

05

Solar system size comparison chart: planets and the Sun

Equatorial diameters from NASA’s fact sheets, largest first, with the ratio to Earth. The Sun’s value is twice its mean radius, Ganymede’s twice its mean radius:

06

Make your own planet size comparison

1. Open the planet size comparison

   It opens with the planets from Mercury to Jupiter next to the Sun, all at the same scale.

2. Switch the line-up

   Under “Ideas to try”, pick “Moons & dwarf planets” for the Moon, Pluto and Ganymede, or “Stars” to see the Sun next to bigger stars.

3. Make the small ones visible

   Earth and the Moon are tiny next to the Sun. Remove the Sun in “Line-up” or use the zoom buttons to see them properly.

4. Choose units and share

   Under “Units”, “ft / in” shows miles and “cm / m” shows kilometers. Tap a body to compare it with the others, then use “Share link” or “Save PNG”.