noun
coma
A cloud of gas and dust surrounding a comet's nucleus.
The comet's bright coma surrounds its small nucleus like a cloud.
Etymology
Greek komē means hair. A comet’s diffuse cloud resembles a head of hair around its solid nucleus, giving the surrounding gas and dust this visual name.
More examples
- As the comet approaches the sun, its coma grows larger.
- Through the telescope, the coma looks like a fuzzy patch.
- Both comets have visible comas, but only one has a long tail.
Forms
coma · comas · comae