If the Moon Were Replaced by Planets
Stand under a night sky and swap the Moon for Jupiter, Saturn, or even the Sun — every body rendered at its true angular size at the Moon's distance. Drag to look around.
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If the Moon Were Replaced by Planets
What would other planets look like in the Moon's place?
The full Moon covers only half a degree of sky, yet it dominates the night. This simulator swaps the Moon for Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, or the Sun at the Moon's distance of 384,400 km, rendering each one at its true angular size over a night landscape.
How to use the night sky simulator
- Pick a body — the scene starts with the real Moon for scale.
- Drag, use the arrow keys, scroll, or pinch to change the view.
- Adjust the phase to light the planet like a waxing or waning Moon.
- Move the distance from 0.25× to 16× the Moon's distance.
Why do planets look like dots in the real sky?
Angular size falls with distance. Jupiter is 40 times wider than the Moon, but it orbits about 1,600 times farther away, so it shrinks to under an arcminute. At the Moon's distance, it would stretch across 21 degrees of sky — more than forty full Moons side by side.
Angular size of each planet at the Moon's distance
| Body | Diameter | Apparent size in the sky | Vs full Moon |
|---|---|---|---|
| Moon (actual) | 3,475 km | 0.52° | 1× |
| Mercury | 4,879 km | 0.73° | 1.4× |
| Mars | 6,779 km | 1.0° | 2× |
| Venus | 12,104 km | 1.8° | 3.5× |
| Earth | 12,742 km | 1.9° | 3.7× |
| Neptune | 49,528 km | 7.4° | 14× |
| Uranus | 51,118 km | 7.6° | 15× |
| Saturn (rings) | 120,536 km (280,440 km) | 18.0° (rings 40.1° face-on) | 35× (77×) |
| Jupiter | 142,984 km | 21.4° | 41× |
| Sun | 1,391,400 km | Earth would be inside it | — |
Apparent size is the full angular diameter of a sphere's limb: 2·asin(radius ÷ distance). For scale, your fist at arm's length covers about 10 degrees. Jupiter would be two fists wide, while Saturn's rings would span roughly four.
A visual thought experiment, not a survivable one
This tool answers only what your eyes would see. A gas giant at 384,400 km would raise extreme tides and destabilize Earth. The Sun is more extreme: its radius is almost twice the Moon's distance, so Earth would be inside it. The simulator flags that scenario and lets you move the Sun far enough away for its disk to fit in the sky.
Planet textures are adapted from the Solar System Scope texture pack, based on NASA imagery and elevation data and distributed under CC BY 4.0.
More interactive science tools
Planets in place of the Moon FAQ
What would Jupiter look like if it replaced the Moon?
Jupiter at the Moon’s distance of 384,400 km would span about 21 degrees of sky — roughly 40 full Moons side by side, or two fists held at arm’s length. Its cloud bands and Great Red Spot would be visible to the naked eye.
How big would Saturn and its rings look in place of the Moon?
Saturn’s globe would cover about 18 degrees, and the A–C ring system, 280,440 km across, would stretch roughly 40 degrees from tip to tip — nearly half the distance from the horizon to straight overhead.
What would the Sun look like at the Moon’s distance?
Earth would be inside it. The Sun’s radius is about 696,000 km — almost twice the Moon’s distance of 384,400 km. The simulator flags this case and lets you move the Sun farther away until its disk fits in the sky.
Would Earth survive a planet at the Moon’s distance?
No, for the larger bodies. This is a visual thought experiment only: a gas giant that close would raise enormous tides, destabilize Earth’s orbit and crust, and expose Earth to dangerous radiation.
How big does the real Moon look in the sky?
The full Moon has an angular diameter of about 0.52 degrees — small enough to cover with a pea held at arm’s length. It looks large because it is the biggest and brightest object in the night sky.
How does the simulator calculate each planet’s apparent size?
It uses the exact angular-diameter formula for a sphere: 2 × asin(radius ÷ distance), with planetary diameters from NASA fact sheets and the Moon’s mean centre-to-centre distance of 384,400 km.
Visual astronomy thought experiment only; gravitational effects are intentionally not simulated.