By Richard McGuire
As the partial solar eclipse passes over the Okanagan next Monday, astronomer Ken Tapping has some advice beyond the obvious need to wear proper eye protection.
“Observe what’s going on around you at the same time,” he says, suggesting people may miss other interesting phenomena if they focus all their attention on the moon passing in front of the sun.
Tapping, who is an astronomer with the National Research Council of Canada’s Dominion Radio Astrophysical Observatory south of Penticton, describes viewing an eclipse in the United Kingdom several years ago.
“As the moon moved across the sun, you started to notice something really weird,” he said.
The light level began going down, but unlike at sunset, the sunlight didn’t get redder. Instead, as the brain starts turning up the sensitivity in the eyes to compensate for the darkening, the ability to see detail diminishes.
Gaps between leaves on trees acted like pinhole cameras, projecting little crescent suns on other leaves and as the wind blew the leaves, it looked like the trees were covered in fairy dust.
Of course that phenomenon may not happen here, but attentive observers may spot other interesting event besides the more obvious one of the sun turning to a crescent shape.
Weather permitting, the partial eclipse should be visible throughout the Okanagan. An event to watch the eclipse at Desert Park in Osoyoos is now sold out.
Around 9:13 a.m., observers will see a little notch on the sun as the moon moves in front of it. By 10:25 a.m., close to 90 per cent of the sun will be covered by the moon. It will all be over at 11:42 a.m., said Tapping.
“Using appropriate eye protection, it will give you a chance to see the sun in quite an unusual way,” he said. “You’ll see the crescent sun, which you don’t get to see very often.”
Solar eclipses aren’t rare in the sense that somewhere on the planet one takes place every year or so, said Tapping. But it’s much more rare that a solar eclipse will occur in a given location.
The eclipse on Aug. 21 is a total eclipse along a band about 100 kilometres wide that crosses the entire United States from the southeast to Oregon in the northwest.
In a total eclipse, the entire sun is covered, except for the corona around it.
“You’d have to drive down to Oregon (to see the total eclipse),” Tapping said, “But if you haven’t got your hotel booked already, you’ve had it.”
Still, southern B.C. including the South Okanagan will provide a higher percentage of the sun covered – around 90 per cent – than other parts of Canada.
“You’re talking about decades between eclipses (in a particular location), so it’s going to be a long time before we see anything like this in the Okanagan or in Western North America again,” said Tapping.
He emphasizes that observers of the eclipse must wear proper eye protection – especially since permanent eye damage can occur without a person realizing it.
Special glasses with cardboard or plastic frames can be purchased from science stores and some museums, but Tapping cautions against buying them from unreliable sources on the Internet where they may not have the right filter material.
People may not realize they’ve done damage to their eyes until sometime later, Tapping cautions, adding that eyes don’t have pain sensors at the back.
Some do-it-yourself filters may block the light, but they don’t block the harmful infrared.
“The infrared does the burning, but you can’t see it, so the light level is comfortable,” he said. “You are happily staring at the sun and the image of the sun is sitting quite still on the back of your eye and you’re just burning the back of your eye.”
Those unable to obtain the proper glasses can make a pinhole camera, which safely projects the image onto a piece of card, he suggests.
Tapping says scientists will also be busy during the eclipse as they conduct research projects.
In one project, ionospheric physicists will team up with amateur radio enthusiasts to observe how the eclipse effects changes in the ionosphere.
The National Research Council will be using a new solar radio telescope at the observatory near Penticton to understand solar activity.
And, in areas where there’s a total eclipse, it provides a rare opportunity to observe the corona, an envelope of gas surrounding the sun.
The corona is extremely hot, but it emits less light than the sun, so it’s not normally visible except when the moon obscures the sun.
“It’s one of the reasons that scientists go chasing all over the world – it’s not just amateur astronomers – to get their instruments down on the path of totality,” said Tapping.