Asteroid
A spacecraft passing through the asteroid belt is less likely to hit an asteroid than to get bored.
Moon landing
The first Moon landing took place in July 1969, after which the crew filled in a customs form.
Comet
On its way out from the Sun, a comet travels tail-first, which astronomers politely call reversing.
Sunlight
Sunlight takes about eight minutes to reach Earth, so the Sun you see is eight minutes out of date.
Pluto
Pluto was discovered in 1930 and won’t finish its first orbit since then until 2178.
Mars
Mars is famous as the Red Planet, yet its sunsets are blue, which nobody had ordered.
Jupiter
Jupiter has had a storm bigger than Earth raging for at least 190 years, and a day just ten hours long.
Saturn
Saturn is less dense than water, so it would float in a bath, if anyone had a big enough bath.
Neptune
Neptune takes 165 years to orbit the Sun, so it completed its first orbit since discovery in 2011.
Venus
Venus takes longer to turn once on its axis than to go all the way round the Sun.