From Dark Stars to Pictures: teacher key

Black Holes, grade 7 edition, written for 7th grade. Long before Einstein, a thinker pictured heavy stars that trap light. Read how scientists have found black holes, caught ripples in space and shown pictures of them.

Read the book. Print this page for the key.

Questions and answers

1. Who thought a very heavy star might trap light?
   • Albert Einstein
   • John Michell (answer)
   • Isaac Newton
2. Einstein's theory predicted gravitational waves in 1916, and LIGO caught them in 2015. About how many years later was that?
   • About 10 years
   • About 1,000 years
   • About 100 years (answer)
3. What is the dark middle of the picture of M87's black hole?
   • A star
   • Its shadow (answer)
   • A planet
4. How are most black holes found?
   • By the glow of nearby gas (answer)
   • By their bright surface
   • By the sound they make
5. What does invisible mean in "Black holes are invisible"?
   • Very old
   • Very loud
   • Cannot be seen (answer)

Words

• singularity: center point
• gravitational: about gravity
• shadow: dark middle
• evaporate: slowly vanish
• merging: joining together