= Neil de Grasse Tyson =

== Astrophysics for People in a Hurry ==
=== Beaverton 523.01 Tyson 2017 ===
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Amusing.  Fairly substantial for the less-informed.  Facts (claims?) I can use are on page 104 of the large print edition:

 . The Macy's parade balloons use almost as much helium as the US military
  . [[ https://www.livescience.com/60998-macys-balloons-wont-use-up-helium.html | 300,000 cubic feet, ~9000 m3 ]]
   . 21 billion m3 in the helium reserve in 2017, 31 billion m3 worldwide
   . 47 million m3/year in the US

 . Big bang cosmology, no more than 1% lithium, no less than 10% helium