by Rex Parker, PhD director@princetonastronomers.org

60^th Anniversary of AAAP!  This fall marks the 60^th year that AAAP has been an astronomy club.  Yes, back in the fall of 1962, in the early years of the space race, AAAP filed for incorporation as a non-profit. We have met nearly every month (Sept-June) without fail ever since.  Now it’s time to decide what we want to do to mark this momentous occasion. Please send your idea on a 60^th celebration event to the editors (editors@princetonastronomy.org) or me for consideration.

Welcome to a new season of AAAP monthly meetings.  Being in the Princeton orbit, naturally AAAP has kept a schedule based on the scholastic year ever since our beginning 60 years ago. So, the first meeting of the season Sept 13 marks a renewal of our monthly gatherings, even though we are not quite ready yet to hold face-to-face meetings again.  Whether by Zoom or in person, these meetings are truly the life-blood of the club, and we urge all new and experienced members to participate. There are many amazing advances in the science of astronomy that we really need to sort out together.  Please refer to my article in the mid-summer edition of Sidereal Times for an assessment of our possible meeting future at the Institute for Advanced Studies.     But for the next 2 months at least we will continue Zooming the monthly meetings. We have some exciting programs lined up and hope you will join us on Sept 13 at 7:30pm for the kick-off of the new season.  See the Program Chair’s section below for information about the guest presentation on Sept 13.

Observatory columns reconstruction completed.  One of the great benefits of the club is being able to use some serious astro equipment at AAAP’s Washington Crossing Observatory. And it isn’t surprising that, from time to time, we need to make significant investments to maintain the facility. In this case, I am pleased to announce that the much-needed concrete reconstruction work on the facility was completed in August.  At long last, 4 new steel-reinforced concrete pillars now support the massive roll-off roof.  The new columns will probably outlive the rest of the building, projecting a sense of strength and symmetry to the observatory (picture below).  The fit and finish are perfect. A big thank you goes to members who contributed to the reconstruction fund (see below).  You really came through – contributions covered essentially all of the approximately $10,000 project.

Contributors to the Observatory Reconstruction Fund:

Water ice on the Moon!  An ongoing theme (dare I say inescapable) in our club is lunar observing.  Only a few years ago wehad several presentations about the moon in recognition of the 50^th anniversary of Apollo.  Now, returning human astronauts to the moon has never been more compelling, especially with the increasing evidence for water ice deep within the south pole craters of the moon.  The excitement is increasing as NASA’s Artemis 1 approaches its launch window at Cape Canaveral.  The Artemis project’s main goal is to return humans to the moon and set the stage for Mars with a moon base near the south pole, where water has been detected instrumentally by NASA’s orbiting probes. The necessary proof, of course, will be for astronauts to actually locate and recover samples of water ice.  

Lunar south pole region observing challenge.  A few of the southmost craters are named after earth’s Antarctic adventurers from a century ago: Amundsen, Scott, and Shackleton (see Figures below). The moon’s rotation axis passes through Shackleton a few km from its center. Observing the polar craters edge-on with a telescope is a real challenge and requires a favorable libration in which the moon’s tilt reveals more of the south pole area. For an excellent high resolution imaging video of the south pole region and Shackleton crater, see this article from NASA and the Planetary Society.  https://www.planetary.org/articles/water-on-the-moon-guide  At the most favorable southern libration over a few nights each month an earth observer can see about 6 degrees beyond the pole.  Sky & Telescope lists the favorable libration dates for north and south poles on the almanac page (center-fold star map) each month.  For more ideas on when and how to observe the south pole craters, see Sky & Telescope, March 2022, “Meet Shackleton Crater: Future Moon Landing Site”.  Here I’m proposing a AAAP observing challenge to see how close to the south pole you can observe, image, and identify craters through a telescope at high magnification.  If you do succeed in getting an image that shows the near-south-pole craters, please send it in to Sidereal Times and we will talk about it at an upcoming meeting.

The deeper craters near the moon’s poles remain in permanent shadow and are extremely cold, below -200 deg C, where water ice is stable even in the vacuum of space. Deep shade turns out to be the key to whether abundant free water ice exists on the moon, and the answer means everything to future human habitation. Moon atlases as recently as the mid-90’s, such as my edition of “Astronomy Atlas of the Moon” (1996) by Antonin Rukl, states “there is no water on the moon – not even in the rocks”.  The first evidence for free water ice came from NASA’s Clementine and Lunar Prospector missions in the late 1990’s, and the instrumental data from more recent missions is convincing.  Imagine an astronaut actually holding ice crystals, and someday even drinking water from the deep polar craters of the moon.  Let’s hope that this happens in the next few years with Artemis, and that the Shackleton crater scenes in the acclaimed science fiction drama TV series, “For All Mankind”, do come true.

The lunar south pole region.  NASA’s Lunar Reconnaissance Oribiter (LRO) flew over the south pole and imaged the craters which hold permanent shading. The polar axis runs through Shackleton crater.  Credit:  NASA/Goddard Space Flight Center Scientific Visualization Studio.    https://svs.gsfc.nasa.gov/3686