August 18

1783 – A huge fireball meteor is seen across Great Britain. Referred to later as a meteor procession, observations indicate that the meteor entered Earth's atmosphere over the North Sea, before passing over the east coast of Scotland and England and the English Channel.

1868 – Astronomer Pierre Janssen discovers the element helium while observing a solar eclipse. It was not until 1895, however, that another scientist would examine the same element and give it its name.

1891 – The first rainmaking experiments in the United States were conducted near Midland, Texas, paid for by a grant from the federal government. The method chosen was to test a theory that rainstorms seemed often to occur where major battles had taken place during the Civil War, and they may have been because of the effect of smoke, dust and disturbances in the air from artillery.

1976 – The Soviet Union’s robotic probe Luna 24 successfully landed on the Moon. The mission returned 170.1 g (6.00 oz) of lunar samples to the Earth.