Q 01/05

What are comet nuclei mostly made of?

A) Ice and dust

B) Molten rock and sulphur

C) Iron and nickel

D) Hydrogen and helium gas

Answer · why

A) Ice and dust

Ice and dust: comets have been called 'dirty snowballs', but later observations suggested 'icy dirtballs' fits them better.

Q 02/05

Why did the Philae lander soon fall silent after touching down on a comet in 2014?

A) It overheated in sunlight

B) It came to rest in shadow

C) Its antenna snapped off

D) A software crash

Answer · why

B) It came to rest in shadow

It came to rest in shadow: its harpoons failed, so it bounced into a shaded spot where its solar panels got too little light, though it woke again in ...

Q 03/05

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

A) Behind it, along its orbit

B) Toward the Sun

C) Along its direction of travel

D) Directly away from the Sun

Answer · why

D) Directly away from the Sun

Directly away from the Sun: sunlight ionises the gas and the solar wind sweeps it outward, while the separate dust tail curves.

Q 04/05

Which process builds a comet's coma as sunlight warms it?

A) Outgassing

B) Ablation

C) Accretion

D) Spallation

Answer · why

A) Outgassing

Outgassing: the material it frees streams out from the comet and forms its tails.

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.