Snacking on comets (Image: HST/NASA)
WHEN the sun dies, it’s not just Earth that will be doomed – the destruction will reach as far as the comets in the outer solar system. That’s according to a new explanation of the behaviour of planetary nebulae – bubbles of gas sloughed off by dying stars (pictured).
There are two methods for calculating the abundance of elements in planetary nebulae: looking at light emitted when electrons and ionised atoms recombine, or looking at the energy emitted by atoms excited by collisions. Yet they yield very different results, a discrepancy that has baffled astronomers for…
