Idaho Skies Transcript for November 7th and 8th

RACHEL
Welcome to Idaho Skies for November 7th and 8th. We’re your hosts, Rachel…

PAUL
…and Paul.

RACHEL
Edmond Halley was born on November 8th, 1656.

PAUL
Halley was an English astronomer and physicist. His earliest astronomical work of importance involved creating an accurate star chart for the Southern hemisphere. Until 1676, the best stellar maps only included the Northern skies. So Halley sailed to the island of Saint Helena to begin his observations and correct this problem. 

RACHEL
His catalog was written in Latin and it listed the name, position, and brightness of 341 stars visible from the Southern hemisphere. The stellar data was followed by notes on his observations on the transit of Mercury. He realized that observations like these could be used to find the size of the solar system. But only if the observations were made using Venus and from several locations across the world. 

PAUL
When Halley arrived back to England, he continued his observations, but mainly of the moon and its motions. Halley knew that years earlier, astronomer Johannes Kepler discovered that the planets orbited the sun in ellipses. Kepler couldn’t however explain why this was the case. Halley wondered if the nature of gravity held the explanation. So he asked Isaac Newton if he could show that a gravitational forced that varied as the distance squared could explain elliptical orbits.

RACHEL
Newton’s theory of gravity and his mathematical proof was the evidence that Halley was looking for. So impressed was Halley with Newton’s work, that Halley paid for the publication of his book on gravity, which we call the Principia for short. Using the work of Newton, Halley predicted that the comet observed in 1682 would return in 1758. This was the first prediction for the return of a comet and now we name the comet after him, or Comet Halley. 
 
PAUL
That’s Idaho Skies for the 7th and 8th of November.

RACHEL
Be sure to read our blog for additional information. It’s at idahoskies.blogspot.com.

For Idaho Skies this is Rachel…

PAUL
…and Paul.

RACHEL
Dark skies and bright stars.