He then began his work on double stars, comets, asteroids, and variable stars.

Presumably this was where he did his research on comets.

The most important were on comets (1860) and the nebular hypothesis itself (1873).

Kobres goes on to suggest an association of mythological birds and comets also outside China.

You can see its effect on comets: it creates the tails that stream behind them.

Knutzen's work on comets was in any case largely motivated by theological concerns.

I take it you're the resident expert on comets.

Cysat's most important work was on comets, and he observed the comet of 1618.

Then there is a gene-tailoring laboratory trying to develop a kind of tree that will grow on comets.

"They will help us better understand the mechanisms that drive conditions on comets."