Rare ‘magic hour’ coming to city on spring equinox HINA ALAM
Avenues’ east-west alignment offers treat for astronomy, photography fans
Edmonton is in for a celestial treat. Edmontonhenge. Framed between concrete and steel, the setting sun will align with the city’s road grid, creating a perfect solar display and bathing the streets in a warm, orange glow.
“When the sun is very low in the sky, it casts a radiant glow of light that gives everything a very pleasing illumination,” Luca Vanzella, past president of the Royal Astronomical Society of Canada, Edmonton Centre, said recently.
“Photographers have coined the term ‘magic hour’ to describe the quality of light that lasts for about an hour before sunset and about an hour after sunrise. A rare and beautiful sight.”
Edmontonhenge happens in March around the spring equinox and in September around the autumnal equinox.
This month, he said the ideal date is March 21, when the sun will be one degree above the east horizon at 7:43 a.m. and above the west horizon at 7:40 p.m.
March 20 and 22 are also good dates to see the event, he said.
Environment Canada promises sun on all three days.
“Edmontonhenge” is a nod to astrophysicist Neil deGrasse Tyson, who coined the term “Manhattanhenge” back in 2001 when he took a photograph of a New York City sunset as the sun could be seen down 34 Street, Vanzella said.
“I planned to take a similar photograph in Edmonton, so I named it similarly,” he said.
Solar spectacles like Manhattanhenge, Edmontonhenge and others (Montrealhenge, Torontohenge, Bostonhenge) get their name from Stonehenge, a 5,000-year-old monument in the United Kingdom that was built to align with the sun’s position, possibly as a way to worship the sun, during the winter and summer solstices.
Edmontonhenge is related to the idea that Stonehenge was set up and used as an astronomical calendar to mark the passage of the seasons, in particular the summer and winter solstices, Vanzella said.
Edmonton is luckier than Manhattan.
Since Edmonton’s streets are aligned with the geographic north-south and east-west lines, the days of Edmontonhenge coincide with the equinoxes, he said.
But in the city of Manhattan, the street grid is rotated 30 degrees east from geographic north, shifting the days of alignment elsewhere into the calendar, he said.
“The streets of Edmonton were mainly laid out in an east-west and north-south grid presumably because the designers preferred to follow geographic east-west and north-south lines,” Vanzella said.
“The ‘henge’ aspect of Edmontonhenge is because the avenues of Edmonton mainly run eastwest, there are two opportunities each year to see the sun rise and set down the avenues.”