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Science Clinic => Physics => Topic started by: azncindy619 on Jul 27, 2018

Title: Changing minds: From the time the idea of dark matter was first proposed in the 1930s, it took ...
Post by: azncindy619 on Jul 27, 2018

Changing minds: From the time the idea of dark matter was first proposed in the 1930s, it took nearly 50 years for astronomers to universally accept the existence of dark matter. Discuss the process by which that acceptance came about.
 
  What evidence was collected, and how was it checked?

Question 2

Order the interior layers of the Sun from the hottest to the coldest.
 
  A) radiation zone, core, convection zone, photosphere
  B) photosphere, convection zone, core, radiation zone
  C) core, radiation zone, convection zone, photosphere
  D) photosphere, convection zone, radiation zone, core

Title: Changing minds: From the time the idea of dark matter was first proposed in the 1930s, it took ...
Post by: Awesome on Jul 27, 2018

Answer to Question 1

The idea was first proposed as an explanation for how galaxies in clusters had such high speeds relative to each other yet did not fly apart. Later astronomers also found that there was some unseen source of mass within spiral galaxies  the speed at which stars orbit does not drop off with distance, as would be expected if the only source of gravity was the stars and gas. A source of unseen mass in galaxies was further confirmed by measuring the high-speed random orbits of stars in elliptical galaxies. Dark matter in galaxy clusters was confirmed by the discovery of very high temperature intracluster gas (heated by moving under the influence of large amounts of unseen matter), and by gravitational lensing of clusters. It was only after the idea of dark matter was used to explain several more phenomena that it became generally accepted.

Answer to Question 2

C