From the Director

Rex
by Rex Parker, Phd director@princetonastronomy.org

Astronomy in Summertime.  The AAAP Observatory at Washington Crossing State Park is up and running and ready for members to see the stars!  We are still limited by the state to having  no more than 12 people in the building at a time, but there’s no limit on the observing field.  A benefit of membership is using the telescope equipment whenever a Keyholder is present to open up and help operate the equipment.  Members can also set up personal telescopes on the observing field next to the building.  Varying sky conditions make it hard to plan sessions, but outside of Friday night public open-house, if you want to access the observatory you are encouraged to send an e-mail to the Observatory Chair (observatory@princetonastronomy.org) or me (director@princetonastronomy.org). We’ll attempt to find a Keyholder who can come out to the Observatory that night. 

It is encouraging that life is trending towards normal around the state.  Princeton University announced the intention to resume on-campus operations this fall.  Later this summer we hope to learn if and when AAAP can return to Peyton Hall auditorium for monthly meetings. 

The Edge of Space.  The past couple weeks have seen some astounding advances in privately developed aeronautical/space adventures.  Virgin Galactic’s suborbital flight took it to ~86 km (53 miles) while Blue Origins rocket reached ~106 km (66 miles) above sea level, passing through the von Karman line.  Although it may mean bragging rights between Richard Branson and Jeff Bezos and their companies, the von Karman line is not really a true boundary of outer space.  The von Karman line at 100 km altitude above sea level is an internationally accepted altitude for where space begins.  But of course physics doesn’t correspond to nice round numbers.  This altitude corresponds only approximately to where aerodynamics stops and astronautics begins, where the atmosphere becomes so thin that aeronautical lift cannot be sustained.  But original citations of the von Karman line indicated  275,000 ft (83 km), and the 100 km definition appears to have been the result of US-Soviet geopolitical agreements in the early 60s.  An astronaut is still defined by the USAF as a person who has flown higher than 50 miles (80 km) above sea level.

Light Dome Dimmer.  The mandate from the New Jersey Supreme Court to expand affordable housing has resulted in big plans for development across the state.  This is a very good thing at many levels, but the increase in light pollution that would result is a problem for all who appreciate the night sky.  Two large residential developments (1077 and 379 units) going forward now in Hopewell Township are located close to the AAAP Observatory (one is only ~2 miles away).  To reduce skyglow, the Environmental Commission and the Planning Board requested significant changes in the developer’s outdoor lighting plans.  In the last few weeks, the developer formally agreed to reduce the number of lighting fixtures by 62% overall (from 545 to 199, and 141 to 58, in the two subdivisions).  They will use sky- and wildlife-friendly 2700K LEDs (amber-tinted) and install adaptive controls which lower light output by half after midnight.  Compared to where it was originally headed, this is a big improvement that will help protect what’s left of the night sky at our Observatory.  There will be significantly less skyglow coming from the intensive development and the “light dome” above them at night will be proportionately dimmer.

The take-home message is that you, citizen amateur astronomer, can make a difference in the future of our night skies. Tune in to the development plans happening now in your town, and speak up at your planning board or environmental commission.  Right now most meetings are being Zoomed, a great way to make your concerns heard. 

SATCON2 Workshop – Astronomers Respond to the Onslaught. As if we don’t already have too much light pollution, the night sky is being disturbed by an unexpected threat — the tracks of satellite “constellations” reflecting sunlight.  Hundreds, soon to be many tens of thousands, of low earth orbit satellites have begun to appear in the night sky.  The good intentions of the Starlink project from SpaceX, and similar efforts planned by others, are to provide fast, low-latency internet access to underserved areas of the planet.  The problem with all this is not only future space debris, but night sky light pollution of a special kind.  Depending on your angular position with respect to the satellites, the low orbital trajectory results in bright visible trails from reflected sunlight as the trains of satellites cross the sky.  Of course North America is the most profitable market, so the satellite intensity will initially be highest here.  The streaking trails of these satellite constellations are seriously damaging to data collection and can overwhelm sensitive instruments for many scientific projects at the big professional observatories.  They disturb the natural darkness of the night sky and can ruin astrophotographs.  Instrumental and software remedies are proving to be extremely difficult.

The American Astronomical Society (AAS) and NSF’s NoirLab are leading the effort to respond to this growing problem that caught the astronomical community off-guard.  There is an opportunity for amateur astronomers to be among the diverse voices of stakeholders for the sky.  I urge you to read up on the issues and consider becoming an amateur member of AAS in order to participate in the expanding conversation on this major topic.  You can become a member of AAS through this link (use AAAP as your affiliation on the application).  https://aas.org/join/classes-membership-and-affiliation. 

Last year, experts joined to assess satellite constellations impact on astronomy and consider possible mitigations.  The meeting in July 2020 was titled, “Impact of Satellite Constellations on Optical Astronomy and Recommendations toward Mitigations”. The findings are summarized at this link:  https://aas.org/satellite-constellations-1-workshop-report    I participated this July in the second workshop, SATCON2.  The main topic was how to implement the strategies and recommendations emerging from SATCON1. The summaries from SATCON2 can be found at this link: https://noirlab.edu/public/media/archives/presentations/pdf/presentation026.pdf 

One of the key recommendations was that the obligation to reduce detrimental effects of satellite constellations on astronomy should be a condition of FCC licensing.  The community engagement section of the workshop stressed that further involvement of amateur astronomers is needed to help amplify the concerns and seek solutions.  The situation seems convoluted, with some people finding the sightings enjoyable, not realizing the havoc they may reek when there are 50,000 of them aloft.  One activity for AAAP members would be to observe the satellite constellations at specific predicted times, and share our impressions within the club. Here’s a link to a site that predicts when they could be seen:  https://findstarlink.com/.  If we can work out the timing, let’s aim for members to meet at the Observatory during a Starlink sky crossing this summer.

This entry was posted in Mid-summer 2021, Sidereal Times and tagged , , , , , . Bookmark the permalink.

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