07/20/2015 – Ephemeris – July 20th anniversaries

Ephemeris for Monday, July 20th.  Today the Sun will be up for 15 hours and 5 minutes, setting at 9:21.   The Moon, 4 days before first quarter, will set at 11:34 this evening, and tomorrow the Sun will rise at 6:16.

July 20th is a special date for this country’s space program and a personal one.  On July 20, 1969 Apollo 11 landed on the Moon, the greatest achievement in the history of space flight.  Seven years later the robot lander Viking 1 landed on Mars.  NASA wanted it to be July 4th, 1976, the Bicentennial, but couldn’t find a smooth landing site in time.  My own connection to the date came in 1963, my first total solar eclipse. We traveled to Quebec province along side the St. Maurice River. To view 60 seconds of totality.  It was the first of four successful total solar eclipse trips I’ve been on..  I’m looking forward to my 5th on August 21st 2017, two years from now which is related to my first, I’ll tell you about that in my blog.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Neil Armstrong about to step off the LM onto the surface of the moon, July 20, 1969. Credit: NASA.

First image sent back from Viking 1 after landing on Mars, July 20, 1976. Credit: NASA/JPL.  Click on image to enlarge.

Video of July 20, 1963 eclipse from the air. I got only one picture of the eclipse and it wasn’t very good.  https://www.youtube.com/watch?v=OT3EW0KIjCc.

The date on the YouTube page is incorrect.  It is July 20, 1963.  I remember the corona being somewhat wedge-shaped, wider to one side than the other.  Other than that it was a typical quiet sun corona.

In the program above I mentioned that the August 21, 2017 solar eclipse was related to my first total solar eclipse.  This is the relationship:  A couple of centuries BC the Chaldean astronomers of ancient Babylonia discovered that eclipses repeated in a cycle lasting 6,585 1/3 days.  That’s 18 years 10 or 11 and 1/3 days depending on the number of leap years spanned.  That period was called the Saros by Sir Edmund Halley or comet fame.  So each eclipse would be visible 1/3 of the Earth farther west.  Note that there are many Saros cycles occurring at the same time, and that eclipses of a particular Saros gradually move northward or southward.  So to have an eclipse recur at the approximate same longitude one must wait 3 Saros cycles. or 54 years and one month approximately.  Thus the third Saros of the July 20, 1963 total solar eclipse will be August 21, 2017.  This Saros series (145) is moving southward.  In 1963 it crosses the US at Alaska and Maine.  Quebec was closer for us, s we went there.  Good thing too.  Maine was clouded and rained out.  For us the clouds parted at the beginning of the eclipse.  The 2015 eclipse will cross the continental US from Oregon to South Carolina.

A squished image of the July 20, 1963 eclipse path.  Right click on the image and select view image to get a correct image.  (works in Firefox).

 

A squished image of the August 21, 2017 eclipse path.  Right click on the image and select view image to get a correct image.  (works in Firefox).