Q 01/05

What are comet nuclei mostly made of?

A) Loose ice, dust and small rocky particles

B) Molten rock and sulphur

C) Solid iron and nickel alloy

D) Frozen nitrogen and methane

Answer · why

A) Loose ice, dust and small rocky particles

Fred Whipple's 1950 dirty snowball model was later refined to icy dirtball after Deep Impact.

Q 02/05

What is the huge, thin atmosphere that surrounds a comet's nucleus called?

A) The corona

B) The mantle

C) The halo

D) The coma

Answer · why

D) The coma

It can grow up to 15 times Earth's diameter, and mostly consists of water and dust.

Q 03/05

In which direction does a comet's ion tail point?

A) Toward Jupiter

B) Toward the Sun

C) Along its direction of travel

D) Directly away from the Sun

Answer · why

D) Directly away from the Sun

Radiation pressure and the solar wind push the tail outward whether the comet is approaching or leaving.

Q 04/05

What is the release of gases from a comet as it warms near the Sun called?

A) Outgassing

B) Solar venting

C) Ablation

D) Sublimation burst

Answer · why

A) Outgassing

It produces the coma and, sometimes, the tail.

Q 05/05

The name comet comes from a Greek term meaning what?

A) An evil omen

B) A wanderer

C) Wearing long hair

D) A fiery messenger

Answer · why

C) Wearing long hair

The Greeks called it the long-haired star.