The sun is about to reach its summer solstice and the longest day of the summer on Sunday, June 21.
To mark the event, a gathering will take place at the ‘Pen Henge’ standing stone array on Munson Mountain in Penticton that evening.
The public gathering is being organized by the Penticton meeting group of the Okanagan Centre of the Royal Astronomical Society of Canada and it will feature safe solar viewing through filtered telescopes.
If skies are clear, participants will gather at Munson Mountain at around 8.15 p.m.. in anticipation of seeing the shadow cast by the sun over the summer solstice stone extending gradually toward the central heel stone. Sunset will take place at 8.50 p.m..
The actual time of the solstice will be at 9.38 a.m.
The Pen Henge standing stone array is a project spearheaded by Chris Purton and the Okanagan Astronomical Society which later became part of OC RASC, and which was supported by Penticton City Council and its Parks Department.
The installation, which is located at the top of Munson Mountain above the large ‘Penticton’ sign on the east side of Okanagan Lake, consists of four stones that delineate the sunset points on the four cardinal dates of the year.
Anchored by the Heel Stone, the Equinox Stone points to the Sun’s sunset point at both the Spring and Fall Equinoxes, while the other two stones mark the Winter and Summer Solstice setting points respectively.
Photos of the array and earlier observances can be viewed on the OC RASC website at ocrasc ca through the Image Gallery link and the Pen Henge folder.
Purton, who is a retired scientist at the Dominion Radio Astrophysical Observatory at White Lake, refined measurements during the summer solstice last year and determined that the moment of sunset will be 8.50.2 p.m,, “provided that the trees on the horizon have not grown appreciably.”
A brass plaque with a brief explanation of the array is permanently attached to the top of the heel stone.