WONDER #2546: How Often is "Once in a Blue Moon'?

Question 1 of 3

What was the main idea of this Wonder?

  1. The moon changes colors each month, even if you don’t notice it.
  2. “Once in a Blue Moon” is an idiom, but it’s also an event that happens once every two-and-a-half years.
  3. The moon appeared blue in the sky after a volcanic eruption in Indonesia in 1883.
  4. Full Moons happen every 29 days.

Question 2 of 3

What do people mean when they say, “Once in a Blue Moon”?

  1. They mean sad events that make people “blue.”
  2. They mean something that happens exactly once every two years.
  3. They mean something that happens every day.
  4. They mean something that happens very rarely.

Question 3 of 3

What volcano erupted in 1883 and caused the moon to appear blue to people in Indonesia?

  1. Mt. Everest
  2. Krakatoa
  3. Mauna Kea
  4. Vesuvius

Check your answers online at https://www.wonderopolis.org/wonder/How-Often-is-“Once-in-a-Blue-Moon”.