Interactive · Thought experiments
What if…
Impossible premises, honest physics. Drag the sliders and watch the solar system deal with the consequences.
The honest questions
Could the Moon actually spiral closer?
No — it is drifting away, about 3.8 cm per year, as tides transfer Earth's rotational energy to the Moon's orbit. Bringing it closer would take civilization-scale energies we cannot muster. But if it did come inside ~18,340 km, Earth's tides would shred it into a ring system — the Roche limit is very real.
How much mass would Jupiter need to become a star?
About 75–80 times its current mass for sustained hydrogen fusion (a true red dwarf star), and around 13 Jupiter masses for deuterium fusion (a brown dwarf). There is no known way to add that much mass — it is pure thought-experiment territory.
Did Earth ever have rings?
Possibly. Some geologists link an intense meteor bombardment 466 million years ago to a small moon that broke apart inside Earth's Roche limit, forming temporary rings. If so, our planet has worn Saturn's jewelry before.
Are the numbers in the lab accurate?
The scaling laws are real: tides fall with the cube of distance, orbital periods follow Kepler's third law, the Roche limit and fusion thresholds are textbook values. The premises are impossible; the physics is honest.