History of Solar System formation and evolution hypotheses moon and Mercury was a moon of Venus but drifted away because of the Sun's gravitational influence. Mars was a moon of Bellatrix. One major argument against exploding planets and moons is that there would not be an energy source powerful enough to cause such explosions. In J. Marvin Herndon's model, inner (large-core) planets form by condensation and raining-out from within giant gaseous protoplanets at high pressures and high temperatures. Earth's complete condensation included a c. 300 Earth-mass gas/ice shell that compressed the rocky kernel to about 66% of Earth's present diameter (Jupiter equates to about 300 Earth masses, which
Formation and evolution of the Solar System of 4.6 billion years, suggesting that the Solar System must be at least this old. Studies of discs around other stars have also done much to establish a time frame for Solar System formation. Stars between one and three million years old have discs rich in gas, whereas discs around stars more than 10 million years old have little to no gas, suggesting that giant planets within them have ceased forming. Note: All dates and times in this chronology are approximate and should be taken as an order of magnitude indicator only. Formation and evolution of the Solar System The