Space is the coolest thing in the universe
By day, Evan Bray is working on next-generation astronomical X-ray detectors in professor David Burrows’s lab. But by night he’s perched on the rooftop of Davey Lab, capturing images of celestial objects millions of light-years away.
“How did I get into it? Well, I’ve always enjoyed looking at pictures of Earth taken from space and of things in space taken from Earth,” he says.
But when Bray started graduate school, he didn’t have any experience with telescopes. And as a teaching assistant for several undergraduate astronomy courses, he had to run a number of sessions at the Davey Lab rooftop observatory. So in order to teach his students, Bray began learning the ins and outs of observational astronomy. And what he saw amazed him.
“There are all sorts of patches in the night sky where there are no stars visible to the naked eye,” he says. “You point a telescope there and it’s just packed up with stuff. It’s crazy! I thought that was mind-blowing. And that was one of my first really eye-opening events.”
From that moment, Bray says, he “embarked on a quest” to capture those sights in photographs—and in color. As it turns out, nearly all the cameras used with telescopes are quite different from the ones that are now ubiquitous in our smartphones.
“With the camera that’s on your phone, you press one button, one exposure, and ‘Boom!’ You have a color photo,” he explains. “Every pixel in your phone’s camera is composed of three smaller subpixels: one red, one green, and one blue. But astronomy cameras don’t have nearly as much light to work with, so the pixels are monochrome, which helps to make the image brighter.”
To do color astrophotography with a monochrome camera, it’s necessary to use a set of filter and take a minimum of three exposures: one with a red filter, one with green, and one blue; those exposures then need to be aligned, stacked, and compressed into a single image, which Bray does with computer software like AstroImageJ and Photoshop. But the key to making a good-looking color photo, he says, is to take many long exposures with each filter.
“One of the longest-exposure photos I’ve done was of the Triangulum Galaxy,” he says. “I took 40 to 50 minutes of exposures in three colors—so about two to three hours total—and I had hundreds of individual images.”
The reason for the length and number of exposures, he explains, is that they help to reduce the “noise” in the image and make it less grainy.
“It makes the object in the center that you’re actually trying to get a picture of ‘pop out’ more,” he says. “The more time that you spend looking at an object, the better it gets.”
Dedicated astrophotographers may spend many hours looking at a single object over several nights. Exactly how much time is required often depends on how reliable the weather is and how often you can count on there being a clear night—conditions astronomers call “good seeing.”
“The weather here is very unpredictable,” Bray says. “So, depending on what I want to look at, I budget an entire night—which basically means from sunset until I get sleepy—and I’ll make a single processed image out of that.”
That’s a lot of work, even for a starry-eyed photographer, to make just a single image. So why would anyone go to the trouble?
“I think it’s a humbling experience to look at things in space or to see things from space,” Bray says. “The perspectives are very different because of the size scales involved.”
Perhaps one of the best examples is a photo of Earth taken from 4 billion miles away by the Voyager 1 spacecraft on its way out of our solar system—titled “The Pale Blue Dot”—which Bray notes is a personal favorite, “one of the most moving pictures ever taken.”
In his book Pale Blue Dot, the eminent astronomer Carl Sagan wrote: “It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known.”
As for his own astrophotography, Bray says his favorite subject is “galaxies, for sure!”
Of all the pictures Bray has taken, one of his favorites is of the Pinwheel Galaxy, its distinct arms standing out sharply against the background of space. Like our own Milky Way Galaxy, the Pinwheel Galaxy is a spiral galaxy. Located 25 million light-years from Earth, it is 170,000 light- years in diameter—nearly twice the size of the Milky Way—and is estimated to contain at least a trillion stars, as many as 10 times the number of stars thought to reside in the Milky Way.
Putting those numbers in context, Bray finds plenty of food for thought about the vastness of space and our place in it. Astronomers estimate the number of galaxies in the universe to be as many as 2 trillion, he explains, each of them home to maybe 100 billion stars or more; by extension, the total number of stars and planets the universe may contain is unfathomably large. When, in that light, you consider the odds that we’re the only intelligent lifeform in the universe, they seem as infinitesimally small as our pale blue dot in that famous photograph.
“Nobody knows the answers, but it’s a cool thing Credit: Evan Bray, Penn State to think about,” Bray says. “There’s a huge number of planets out there, a huge number of stars, and I think that these things should serve as inspiration that there’s so much else out there. You shouldn’t feel small or insignificant. You should feel cool that you get to be a part of it, like being part of a small piece in a large, very cool, very exciting puzzle.”
Even after years of stargazing and shutterbugging, Bray still maintains his sense of wonder.
“I regularly have my mind blown about how large things are in space,” he concedes with a laugh. “Even on a small scale, things are mind- blowing. Space is the coolest thing in the universe!”
Evan Bray is a graduate student in the Department of Astronomy and Astrophysics at Penn State.