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Mini-Quiz: Black Holes

by Ron Kurtus (updated 18 January 2022)

Take this Mini-Quiz to check your understanding of the lesson material.

1. Why does the diameter of a star decrease when it runs out of fuel?

It cools down, reducing any thermal expansion

Pressure from reflected light cause the decrease in size

In order to absorb more fuel from space

2. If the mass of a star was twice that of our Sun, what would be its event horizon radius if it became a Black Hole?

About 3 km

About 6 km

No one is sure, because they can't see such a Black Hole

3. How are Black Holes sometimes detected?

By shining a bright light into them

There is no way to detect them

By the effect they have on neighboring stars

If you got all three correct, you are on your way to becoming a Champion in Astronomy. If you had problems, you had better look over the material again.

Observe things around you

Resources and references

Ron Kurtus' Credentials


Black Holes Frequently-Asked-Questions by Ted Bunn - thorough explanation of Black Holes from the University of California-Berkeley

Virtual Trips to Black Holes and Neutron Stars by Robert Nemiroff - explanations and MPEG movies showing how things look from NASA (most computers can show these short animations)

Black Holes and Beyond - a more complex explanation of Black Holes from the University of Illinois

Astronomy Resources


(Notice: The School for Champions may earn commissions from book purchases)

Exploring Black Holes: Introduction to General Relativity by Edwin F. Taylor, John Archibald Wheeler, Benjamin/Cummings Publishing (2000) $37.33 - top ranked book on the subject

Black Holes and Time Warps: Einstein's Outrageous Legacy by Kip S. Thorne, Frederick Seitz and Stephen Hawking, W.W. Norton & Company (1995) $18.95 - popular book, including views of Hawking

Top-rated books on Black Holes

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