Solar System Planet Size Comparison: The True Scale of Our Worlds

The solar system contains objects of wildly different sizes — from Mercury, smaller than some moons, to Jupiter, large enough to contain over 1,300 Earths. Visualizing the true scale of the solar system is genuinely humbling and is one of the most powerful ways to grasp the nature of our cosmic neighborhood.

Planet Diameters: Ranked Smallest to Largest

• Mercury: 4,879 km — 0.38× Earth. Smaller than Ganymede (Jupiter's largest moon)
• Mars: 6,779 km — 0.53× Earth
• Venus: 12,104 km — 0.95× Earth (almost identical to Earth)
• Earth: 12,742 km — 1× (baseline)
• Neptune: 49,244 km — 3.9× Earth
• Uranus: 50,724 km — 4.0× Earth
• Saturn: 116,460 km — 9.1× Earth
• Jupiter: 139,820 km — 11.0× Earth (largest planet)
• The Sun: 1,392,700 km — 109× Earth (for reference)

How Many Earths Fit Inside Each Planet?

• Inside Mercury: 0.055 Earths (Mercury is smaller than Earth)
• Inside Venus: 0.86 Earths
• Inside Mars: 0.15 Earths
• Inside Neptune: 57 Earths
• Inside Uranus: 63 Earths
• Inside Saturn: 763 Earths
• Inside Jupiter: 1,321 Earths
• Inside the Sun: 1,300,000 Earths

Distance Comparison: How Far Apart Are the Planets?

Sizes alone don't capture the scale of the solar system — the vast distances between planets are even harder to grasp:

• Earth to Moon: 384,400 km — would fit about 30 Earths side by side
• Earth to Sun: 149.6 million km (1 AU)
• Sun to Mars: 227.9 million km (1.52 AU)
• Sun to Jupiter: 778 million km (5.2 AU)
• Sun to Saturn: 1.43 billion km (9.6 AU)
• Sun to Neptune: 4.5 billion km (30 AU)
• Sun to Voyager 1: 24+ billion km (160+ AU)

A Walking Scale Model

If the Sun were the size of a basketball (24 cm diameter), you would need a playing field 3 km across to fit the entire solar system to scale. Earth would be a small bead 26 meters from the Sun basketball. Jupiter — a marble — would be 135 meters away. Neptune — a tiny bead — would be 780 meters away. Voyager 1 would be almost 4 km from the basketball. The nearest star, on this scale, would be approximately 7,000 km away — about the distance from New York to London.

The Biggest Objects in the Solar System

Beyond the 8 planets, some other objects are worth noting in scale context:

• Ganymede (Jupiter's moon): 5,268 km — larger than Mercury
• Titan (Saturn's moon): 5,150 km — also larger than Mercury
• Callisto (Jupiter's moon): 4,820 km — nearly Mercury's size
• Eris (dwarf planet): 2,326 km — similar to Pluto
• Pluto (dwarf planet): 2,376 km