For decades, astronomers have been confident that relatively low-mass stars such as our sun form by the gradual accretion, or buildup, of mass from a disk of gas and dust.

All these diverse constituents are aggregated together to form chondritic meteorites, like Allende, that have chemical compositions much like that of the Sun.

Far from the sun, in the outer solar system, beyond Jupiter's orbit, temperatures are low enough to permit ices to form out of water and out of gases like methane and carbon dioxide.