What happens if Earth were 100 times heavier?
In GalaxySim’s N-body run, the Moon — suddenly moving far too slowly for Earth’s stronger pull — falls straight onto Earth in less than a day of simulated time. Nearby satellites crash too.
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Gravity simulator: what if Earth were 100× heavier?
Select any planet, drag its mass from ×0.01 to ×1000, and every other body responds — computed with full N-body gravity on the real solar system.
Ready-made experiments
Earth × 100
The Moon falls in within a day. Satellites follow.
Sun × 2
Every orbit tightens and speeds up at once.
Jupiter × 50
A near-star stirs the asteroid belt and Mars over centuries.
Rogue star fly-by
A half-solar-mass star passes 100 AU out. Watch the outer planets over decades.
In the simulator: open OPERATIONS (or Lab on a phone), pick a scenario and press Run. The scenario editor lets you create your own star or planet.
Frequently asked questions
What happens if the Sun doubled in mass?
Every planet would suddenly be moving too slowly for a circular orbit around the heavier Sun. Orbits tighten into ellipses that dive closer to the Sun, and years get shorter.
What if Jupiter were 50 times more massive?
At about 5% of the Sun’s mass Jupiter would be a small star. Its pull stirs up the asteroid belt and Mars within centuries; you can watch it happen in fast-forward.
How does the gravity simulator work?
Normally the planets follow exact Kepler orbits. When you change a mass, GalaxySim switches to N-body gravity: every body pulls on every other, integrated with a leapfrog method in steps of 6 hours, in a background thread. The display blends smoothly between steps, and time slows down automatically if your device can’t keep up.