Green comet: Viewing, photography tips for Vancouver, BC

A passion for space and photography is not all it takes to become a skilled astrophotographer.

But even a young local space enthusiast has spent countless hours learning the advanced mechanisms behind capturing detailed images of celestial objects. The results of his efforts are nothing short of fascinating, drawing the attention of numerous publications as well as NASA, which singled out one of his photos as a coveted Astronomy Picture of the Day.

Liron Gertsman’s crystal-clear images may seem effortless – like he’s positioned his tripod at just the right moment and captured a quick snapshot of a stunning cosmic event – but space photography is a time-consuming, multi-faceted process.

Comet C/2022 E3 (ZTF), a rare green comet that has not passed the skies of Metro Vancouver in a whopping 50,000 years, makes its closest approach to Earth on Wednesday (February 1). To put that in perspective, that was around the same time that the Neanderthals last walked the planet.

While Metro Vancouver residents may be able to spot the comet with the naked eye, it’s a good idea to bring 40-50mm binoculars or a small telescope if you want to see detail.

What you can and cannot see with the naked eye

Like Gertsman said Vancouver is great, the comet does not appear exactly as you would have hoped without additional help. While he could make out it from around town a few days ago, he said it looked more like a star with a blurry glow; it was impossible to see the tail and it did not appear green.

But that’s not because the comet doesn’t have a green hue. Instead, the human eye is unable to discern the stunning color of the dark night sky (we’re not nocturnal, no matter how many of us would like to be).

What makes this comet so interesting, however, is that Gertsman was able to discern a striking turquoise color before beginning his edit.

“It looks totally ‘turquoise’ in a single shot with a basic camera on a tripod, even without a fancy setup,” he explained. “That’s actually a good way to know you’re looking at the comet because it looks like a star surrounded by a turquoise glow.”

What requires editing is the detail of the “tail”. Or, as Gertsman noted, both “tails” of the comet.

“Two tails are visible in photos of the comet: an ion tail and a dust tail. The ion tail (also called the gas tail) appears as a fairly straight, gray or bluish stream of glowing gas emerging from the comet by solar wind (a stream of particles from [the] Sun). So the ion tail is pointing straight at the sun,” he explained.

“The dust tail consists of solid particles that are repelled by solar radiation. The dust tail does not glow, but the solid particles are illuminated directly by sunlight. The dust tail appears wider (rather fan-like). and warmer in color compared to the ion tail.”

The comet’s light turquoise atmosphere, known as the coma, is also visible. While it’s possible to observe with the naked eye outside of the city, the color is difficult to discern without a camera.

Catch the green comet as it passes Earth

Gertsman used more sophisticated tools to create his final image, including a telephoto mirrorless camera, a tripod, and a Skywatcher star tracker. The Star Tracker fits on a tripod and allows astrophotographers to follow the stars.

“If you show [the star tracker] at the North Star it rotates at basically the same speed as the earth or the apparent speed of the sky rotating with the earth. And then I can take really long exposures and reveal a lot of detail in the night sky without becoming like streaky stars, which usually happens when you don’t have the star tracker because we’re on a planet that’s spinning. ” he explained.

Gertsman also set his camera up after 2:15 a.m., which was after the moonset on Jan. 29, when he took the picture. He stayed out until about 6:30am to collect enough frames for the last photo.

The editing process, which took several days, involved a technique called image stacking, which involved lining up multiple photos and averaging each pixel.

“It basically creates a much sharper, brighter image [that allows you to see] the detail in these tails is much better than in a single image,” he noted.

While Wednesday’s Vancouver weather forecast calls for no clear skies — the night the comet makes its closest approach to Earth — Gertsman stresses that there are multiple opportunities to catch it in the days that follow (weather permitting, of course). ).

The last stunning image he captured near Squamish was taken about three days before the big night, so local space enthusiasts should have a chance to snap one that’s just as bright in the next week or so.

Follow Gertsman on Instagram or check out his photography on his website.