Q 01/05

Which planet is the hottest in the Solar System?

A) Venus

B) Mercury

C) Mars

D) Jupiter

Answer · why

A) Venus

Mercury is closer to the Sun, but Venus's thick atmosphere traps heat like a blanket, so its surface is hot enough to melt lead.

Q 02/05

Which is the smallest planet in the Solar System?

A) Mars

B) Mercury

C) Neptune

D) Uranus

Answer · why

B) Mercury

Mercury is only a little bigger than our Moon and races around the Sun in just 88 days.

Q 03/05

In 2006, Pluto was officially reclassified as what kind of object?

A) A giant comet

B) A moon of Neptune

C) A dwarf planet

D) A rogue asteroid

Answer · why

C) A dwarf planet

Pluto is smaller than Earth's Moon, and it shares its neighbourhood with lots of other icy bodies in the Kuiper belt.

Q 04/05

A light-year is a unit used to measure what?

A) Time

B) Brightness

C) Speed

D) Distance

Answer · why

D) Distance

It is how far light travels in one year, which is nearly six trillion miles.

Q 05/05

Which scientist used his own telescope to spot the four largest moons of Jupiter?

A) Isaac Newton

B) Albert Einstein

C) Galileo Galilei

D) Nicolaus Copernicus

Answer · why

C) Galileo Galilei

Those four moons are still called the Galilean moons: Io, Europa, Ganymede and Callisto.