Q 01/05

What is the closest star to Earth, besides the Sun?

A) Epsilon Eridani

B) Barnard's Star

C) Proxima Centauri

D) Sirius

Answer · why

C) Proxima Centauri

Proxima Centauri is the dimmest of the three stars in the Alpha Centauri system: no star lies nearer to the Sun, yet this red dwarf is too faint to se...

Q 02/05

Which test for planethood did the former ninth planet fail in 2006?

A) Having a moon

B) Clearing its orbit

C) Orbiting the Sun

D) Being round

Answer · why

B) Clearing its orbit

Clearing its orbit: the demoted world shares its zone with swarms of icy bodies, and the 2005 discovery of Eris, a rival of similar size, pushed astro...

Q 03/05

As of 2025, which planet had overtaken Jupiter as the one with the most confirmed moons?

A) Saturn

B) Mars

C) Uranus

D) Neptune

Answer · why

A) Saturn

Saturn pulled far ahead when astronomers stacked hours of telescope images to pick out faint, distant moons; 128 confirmed in March 2025 lifted its to...

Q 04/05

What is the point of no return around a black hole called?

A) Ergosphere

B) Accretion disk

C) Singularity

D) Event horizon

Answer · why

D) Event horizon

Past the event horizon, the speed needed to escape exceeds the speed of light, the fastest anything can travel, so whatever crosses it can never come ...

Q 05/05

Approximately how long does it take sunlight to reach Earth?

A) About 2 minutes

B) About 8 minutes

C) About 20 minutes

D) About 1 hour

Answer · why

B) About 8 minutes

About 8 minutes: sunlight needs roughly 8 minutes 20 seconds to cross the 150 million km to Earth, so we always see the Sun as it was that long ago.