> how did you know there were no planes in the area, etc..?
See and avoid works well under the conditions described: astronomy -- night time, dark-adapted, clear sky.
Aircraft lights stand out quite well against that background, and you can hear them coming early enough to close the shutter on the time exposure to avoid having those red and green and white streaks across the picture.
I doubt someone's figured out how to fly silent unlit gliders at night.
Astronomy amateurs wanting to be careful can get the aircraft navigation maps
Area Control Center - Wikipedia, the free encyclopedia
to make sure you're not in a regular flight path, and those will also give you the areas where flight is controlled, a good way to tell where to expect airplanes regularly.
Handy site:
AeroPlanner.com
(Purple on the map marks laser operations for aircraft to avoid -- up to 60,000 feet elevation in this example)
Cue Crocodile Dundee: "You call that a laser? THIS is a laser ..."
8/7433 - NM .. LASER RESEARCH SUNSPOT, NM LASER RESEARCH WILL BE CONDUCTED AT APACHE POINT OBSERVATORY ... AT AN ANGLE OF 090 DEGREES FROM THE SURFACE, PROJECTING UP TO 60000 FEET. AVOID AIRBORNE HAZARD BY 5 NAUTICAL MILES. THIS BEAM IS INJURIOUS TO PILOTS/AIRCREWS AND PASSENGERS EYES. ALBUQUERQUE /ZAB/ ARTCC, 505-856-4500, IS THE FAA COORDINATION FACILITY. WIE UNTIL UFN. CREATED: 31 OCT 16:39 2008