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Got Calcium?


1. The mass of the Sun is 2.0 x 1030 kg. With the mass of Cas A at 20 times the mass of the Sun, and 0.05% of that mass being calcium, the amount of calcium in Cas A is

= (20 x 2.0 x 1030 kg) x 0.0005
= 2.0 x 1028 kg of Ca in remnant

2. The total number of glasses of milk is then

= total Ca in remnant / Ca in 1 glass
= (2.0 x 1028 kg) / (300 mg x 1kg/106mg)
= 6.7 x 1031 glasses of milk!

3. A number of web sites give the total milk production in the United States. For example the National Agricultural Statistics Service gives the monthly milk production. From this, we learn that during March 2008, the average cow produced about 1,800 pounds of milk, and there are 8.44 million milk cows in America. So, performing one of the best astronomy calculations ever,

  • Each cow produces 1800 lbs = 816.5 kg per month or 26.3 kg per day for a 31-day month. (The conversion to days is not necessary, but is more meaningful.)
  • With each glass of milk being 237 gm, each cow produces 111 glasses per day.
  • All the cows in the U.S thus produce (8.44 x 106 cows) x 111 glasses/cow = 9.4 x 108 glasses of milk per day.
  • With Cas A having the equivalent of 6.7 x 1031 glasses of milk, it will take all the cows in America
  • 6.7 x 1031 glasses / 9.4 x 108 glasses/day
    7.1 x 1022 days
    2.0 x 1020 years

    to produce the amount of milk that contains the same amount of calcium that is in Cas A.

    The universe is only 13.7 x 109 years old.


A service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA/GSFC

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