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 do astronomers typically spot an invisible black hole in deep space?

   Answer: By its pull on nearby stars

   Why: The Milky Way's unseen central mass weighs 4 million Suns, and the star S2 laps it every 16 years at nearly 3 percent of light speed.

2. 2 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.

3. 3 Hard

   Which 1970s satellite confirmed the first likely black hole, Cygnus X-1?

   Answer: Uhuru

   Why: It launched from a sea platform off Kenya on 12 December 1970, the anniversary of independence; its name is Swahili for freedom.

4. 4 Easy

   What happens to spacetime around a rapidly rotating black hole?

   Answer: It gets dragged along

   Why: Frame-dragging means that within a rotating black hole's ergosphere, it is physically impossible to stand still.

5. 5 Medium

   What is the ring of orbiting light around a black hole?

   Answer: Photon sphere

   Why: Around a non-rotating black hole it sits at 1.5 times the event horizon radius, and every light orbit there is unstable.

6. 6 Hard

   What is the theoretical limit for a neutron star's mass?

   Answer: Tolman-Oppenheimer-Volkoff limit

   Why: Oppenheimer and Volkoff got just 0.7 solar masses in 1939 by omitting nuclear forces; modern models put the limit at 2.2 to 2.9.