| Origin | The sun formed instantly as a homogeneous body from an interstellar cloud with no mass accretion or mass loss. | The sun formed in a timely manner by accretion of fresh supernova debris on the collapsed core of a supernova. |
| Main source of luminosity | Hydrogen-fusion in the core | Energy from a supernova core |
| Main nuclear reactions | Hydrogen fusion: 4 1H + 2 e- �> 4He + 2 v + 27 MeV | Neutron emission: <1n> �> 1n + 10 MeV Neutron decay: 1n �> 1H + 0.8 MeV Hydrogen fusion: 4 1H + 2 e- �> 4He + 2 v + 27 MeV |
| Energy from hydrogen fusion | � 100 % | � 38 % |
| Solar neutrino flux, excluding CNO neutrinos* (observed/predicted) | � 50 % | � 130 % |
| Observable by-products of nuclear reactions | 1. Neutrinos from the decay of fusion products in the core. | 1. Neutrinos from the decay of fusion products in the core. 2. Hydrogen ions escape from the surface in the solar wind. |
| Major elements in the sun | Hydrogen, helium, carbon | Iron, nickel, oxygen, silicon |
| Comparable meteorites | None. Only about 0.1 % of the sun has the composition of carbonaceous chondrites. | About 99% of the sun has the same composition as ordinary meteorites. |
| Comparable planets | Giant planets far from the sun | Rocky planets close to the sun |