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Explorations An Introduction to Astronomy, 3/e
Thomas T. Arny

Cosmology

Essay



1

M31, the great galaxy in Andromeda and a member of the Local Group of galaxies, is approaching us. Does this mean that the Hubble law is wrong? Why?
2

Suppose the Hubble constant were discovered to be five times larger than is now believed. How would that affect our estimate of the age of the Universe?
3

Does it bother you that the Universe may expand forever?
4

Why do most stars, including our own Sun, contain more helium than the 24% formed during the Big Bang?