Black Holes quiz

More questions about Black Holes

These visible examples show the question style. LearnClash turns the full topic into ranked duels and spaced repetition.

1. 1 Easy

   How are the largest black holes, containing millions of solar masses, officially classified?

   Answer: Supermassive

   Why: Astronomers believe nearly every giant galaxy in the observable universe anchors one of these giants at its core.

2. 2 Medium

   To become a black hole, Earth must shrink to what size?

   Answer: the size of a marble

   Why: The whole planet would have to fit in a ball under 2 centimetres across. The same recipe would squeeze the Sun to about 6 kilometres wide.

3. 3 Hard

   What is the simplest type of black hole with zero charge?

   Answer: Schwarzschild black hole

   Why: Schwarzschild found the solution while serving on the Russian front and posted it to Einstein in December 1915, under five months before his death.

4. 4 Easy

   What do two colliding black holes primarily release into space?

   Answer: Gravitational waves

   Why: LIGO's first detection, in September 2015, came from a merger that turned about three suns of mass into energy in a fraction of a second.

5. 5 Medium

   How do astronomers detect black holes that are not actively feeding?

   Answer: Gravitational lensing

   Why: The one unambiguous isolated case, OGLE-2011-BLG-0462, took years of Hubble follow-up to confirm from the way it bent a background star's light.

6. 6 Hard

   What theory describes black holes as having no distinguishable outer features?

   Answer: No-hair theorem

   Why: Wheeler popularized the line that black holes have no hair; lacking a general proof, mathematicians still call it a conjecture.