NASA image via https://commons.wikimedia.org/wiki/File:SE1939Apr19A.png .
On April 19, 1939 there was a partial eclipse of the sun that could be seen in southern California but it wasn’t much. Learn more at http://www.eclipsewise.com/solar/SEprime/1901-2000/SE1939Apr19Aprime.html . The area of totality was in Alaska and the North Pole as shown in the image above.
If one were on the moon and there was an eclipse of the sun by the earth, it might look like this illustration appearing in a 1939 issue of National Geographic magazine.
Image: Albert Einstein and Leó Szilárd from
“The Einstein–Szilárd letter was a letter written by Leó Szilárd and signed by Albert Einstein that was sent to the United States President Franklin D. Roosevelt on August 2, 1939. Written by Szilárd in consultation with fellow Hungarian physicists Edward Teller and Eugene Wigner, the letter warned that Germany might develop atomic bombs and suggested that the United States should start its own nuclear program. It prompted action by Roosevelt, which eventually resulted in the Manhattan Project developing the first atomic bombs.”
Excerpt from https://en.wikipedia.org/wiki/Einstein%E2%80%93Szil%C3%A1rd_letter .
Read the letter here: http://www.atomicheritage.org/key-documents/einstein-szilard-letter .