Riddles about planets, moons, stars and the space between them. Space is unusually good riddle material because its facts are already strange enough to sound like puzzles.

These work well alongside a space topic in a classroom. Every riddle here has its answer on the page.

3.EasyWater Riddle

When are eyes not eyes?

  • A.When they are closed
  • B.When they are blind
  • C.When they are asleep
  • D.When the wind makes them water.
Answer: When the wind makes them water.

This is a play on 'eyes' sounding like the pronoun 'ayes', and tearing up in the wind.

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5.MediumWater Riddle

A man buys a glass and fills it halfway with water. Is it half full or half empty?

  • A.Half full
  • B.Both are equally correct
  • C.Neither, it depends on perspective only
  • D.Half empty (because it was empty to begin with, it was 2/2 empty, now it is 1/2 empty).
Answer: Half empty (because it was empty to begin with, it was 2/2 empty, now it is 1/2 empty).

The riddle plays with the starting condition of the empty glass before any water was added.

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12.HardWater Riddle

A traveler starts a journey. For the first week he goes east. The second he goes in all directions. The third he flies up into the sky. In the fourth he comes back down. Who is the traveler?

  • A.A bird
  • B.A cloud
  • C.A river
  • D.An iceberg (travels as ice, flows as water, evaporates to sky, falls as rain).
Answer: An iceberg (travels as ice, flows as water, evaporates to sky, falls as rain).

Think of the full water cycle: solid ice, flowing liquid, rising vapor, and falling precipitation.

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14.MediumWater Riddle

A girl walked into a bar and ordered some water. The bartender then threw a big hairy spider at her. A few minutes later, the girl thanked the man and walked out. Why?

  • A.She was afraid of spiders and left quickly
  • B.It was a prank between friends
  • C.She won a bet
  • D.The girl had hiccups; the man scared them away by throwing the spider.
Answer: The girl had hiccups; the man scared them away by throwing the spider.

A sudden scare is a classic (if odd) home remedy people use to stop hiccups.

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16.HardWater Riddle

Two mothers and two daughters went to the grocery store to buy watermelons. Strangely, they only walked out of the grocery store with three watermelons, but this was enough for each of them to have one watermelon. How is it possible?

  • A.One watermelon was shared
  • B.They miscounted
  • C.There were actually four melons
  • D.Only three people: a grandmother, mother, and daughter (the grandmother is the mother's mother and the mother is the daughter's mother).
Answer: Only three people: a grandmother, mother, and daughter (the grandmother is the mother's mother and the mother is the daughter's mother).

Count generations rather than people: one woman can be both a mother and a daughter at once.

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21.MediumWater Riddle

How can you put some water in a colander?

  • A.Pour it in very slowly
  • B.Use a bag inside the colander
  • C.It's impossible
  • D.Freeze water into ice and put the ice in the colander.
Answer: Freeze water into ice and put the ice in the colander.

Turning the water into a solid, ice, lets it stay inside the holes rather than leaking through.

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29.HardWater Riddle

While stranded in the desert, you come across two creatures offering water. Only, one has no nose, and one has spines. They say that one has poison, and the other will keep you going for a few more hours. Which one can't you trust?

  • A.The one with spines
  • B.Both are trustworthy
  • C.Neither is trustworthy
  • D.The one with no nose (a snake with poison; the other is a cactus).
Answer: The one with no nose (a snake with poison; the other is a cactus).

A snake has no external nose, while a cactus is covered in spines and holds drinkable water.

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38.HardWater Riddle

In Jamaica, if you drop a steel ball weighing five pounds from a height of 45 inches, will it fall more rapidly through the water at 20 degrees Fahrenheit or water at 40 degrees Fahrenheit?

  • A.20 degrees Fahrenheit
  • B.They fall at the same rate
  • C.Neither, it wouldn't sink
  • D.40 degrees Fahrenheit (at 20 degrees the water would be ice)
Answer: 40 degrees Fahrenheit (at 20 degrees the water would be ice)

At 20°F, water would already be frozen solid ice, not liquid water for the ball to fall through.

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48.HardWater Riddle

If boiling water is poured into a thick drinking glass as well as a very thin wine glass. Which of the two is more likely to crack?

  • A.The thin glass, because it's fragile
  • B.Neither will crack
  • C.Both will crack equally
  • D.The thick glass, due to uneven heat expansion stress
Answer: The thick glass, due to uneven heat expansion stress

Thick glass heats unevenly, creating more internal stress than thin glass, which warms quickly and uniformly.

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77.HardWater Riddle

You want to boil a two-minute egg. If you only have a three-minute timer (hourglass), a four-minute timer, and a five-minute timer, how can you boil the egg for only two minutes?

  • A.Use the four-minute timer twice
  • B.Use only the five-minute timer
  • C.Combine all three timers
  • D.Turn the three and five-minute timers over when water boils. Put the egg in when the three-minute timer runs out, remove it when the five-minute timer finishes.
Answer: Turn the three and five-minute timers over when water boils. Put the egg in when the three-minute timer runs out, remove it when the five-minute timer finishes.

The gap between the three and five minute timers is exactly two minutes.

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83.HardWater Riddle

The rungs of a 10-foot ladder attached to a ship are 1 foot apart. If the water is rising at the rate of one foot an hour, how long will it take until the water covers the ladder?

  • A.Ten hours
  • B.Five hours
  • C.One hour
  • D.It will never cover the ladder because as the water rises, so will the floating ship.
Answer: It will never cover the ladder because as the water rises, so will the floating ship.

Since the ladder is attached to a floating ship, the whole ship rises with the tide too.

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87.HardWater Riddle

A woman shoots her husband. Then she holds him underwater for over 5 minutes. Finally, she hangs him. But 5 minutes later they both go out and enjoy a wonderful dinner together. How can this be?

  • A.She used a stunt double
  • B.It was all a dream
  • C.He was immortal
  • D.The woman was a photographer. She shot a picture of her husband, developed it, and hung it up to dry.
Answer: The woman was a photographer. She shot a picture of her husband, developed it, and hung it up to dry.

The words 'shoots', 'underwater', and 'hangs' all describe steps in developing a photograph.

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88.HardTree Riddle

A woman is walking down a street night at a constant pace. As she passes the street light, she notices that her shadow becomes longer. Does the top of her shadow move faster, slower or the same when the shadow is longer as when it is shorter?

  • A.It moves faster when the shadow is longer.
  • B.It moves slower when the shadow is longer.
  • C.It stops moving entirely.
  • D.This point maintains a constant speed, independent of the lenght of the shadow.
Answer: This point maintains a constant speed, independent of the lenght of the shadow.

Using similar triangles, the tip of the shadow's speed stays proportional and constant regardless of shadow length.

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89.HardTree Riddle

There are 50 horses and 50 kings riding along an old dirt road. They came to a peach tree with 50 peaches. Each took one, yet there were still 49 left. How is this possible?

  • A.There were actually 100 peaches.
  • B.Only one horse took a peach.
  • C.It's a trick, it's impossible.
  • D.Each is the name of one of the kings and he's the only one that took one!
Answer: Each is the name of one of the kings and he's the only one that took one!

The trick is that 'Each' is used as a proper name (one of the 50 kings), so only that single king actually took a peach, leaving 49.

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94.MediumTree Riddle

I climbed a cherry tree, where I found cherries. I didn't pick cherries, nor did I leave cherries. How did I achieve this?

  • A.I ate the cherries instead.
  • B.I only looked at the cherries.
  • C.There were no cherries at all.
  • D.The cherry tree held two cherries. I pick a cherry and left a cherry.
Answer: The cherry tree held two cherries. I pick a cherry and left a cherry.

With exactly two cherries, taking one still leaves one behind, satisfying both conditions.

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Frequently asked questions

School-level at most. Most rely on facts a curious ten-year-old already knows.