Moon landing anniversary

Humans first stood on the Moon 49 years ago.

This is the evening sky, as seen from North America, on 1969 July 20.  Apollo 11’s landing module touched down on that day at 20:17 by Universal Time (4 or more hours earlier by American clocks).  That was about 6 hours before the time of our picture, and so was in daylight for America.  The Moon was New on 1969 July 14, and was to be at First Quarter on July 22, so it was now a bright crescent,  Viewers could have picked it in the afternoon, at the time of the landing.

Though the landing module (“Eagle”) touched down at that time, Neil Armstrong stepped onto the surface about six hours later, July 21 2:56 UT.  So that was close to the time of our picture.  Buzz Aldrin joined him twenty minutes later, and they spent over 21 hours on the Moon, while Michael Collins stayed in the command module, piloting it in lunar orbit.

At the same time this year

you’ll see the same constellations (it’s the same sidereal time, “starry time”) but the Moon and planets are in different places.  (Jupiter has gone  4.13 times around the sky, and Uranus has advanced off the picture to the left, in Pisces.)

I’m not much for anniversaries, and this one might be better kept for the 50th.  But John Goss, ever alert to the evolutions of the sky, happened to say in an email of last month: “I’ve been looking into where the moon was in the sky during the first moon landing. It was near Spica and Jupiter. Unknown to many people, Jupiter at the time was in conjunction with Uranus, being separated by about 30 arc minutes.”  As you can see, he was right.

Worth celebrating is that John has served 16 years on the board of the Astronomical League, the last four as President; he will be retiring from these offices on August 31.  You can see his face along with his article for the January 2017 Sky & Telescope, “Fifty Years of the Astronomical League Observing Programs.”  The nebula Goss Amer, and the month Aw Goss, will be named in his honor, next April 1.