By Jonny Lupsha, Wondrium Staff Writer
Coronavirus lockdowns are causing unprecedented clear skies worldwide, The Guardian reported. The tremendous decrease in air pollution is promising for home astronomers and asthmatics alike. Stargazing opportunities are abundant.
According to The Guardian, one silver lining during the coronavirus pandemic has been the incredibly diminished levels of air pollutants being generated. “The coronavirus pandemic is shutting down industrial activity and temporarily slashing air pollution levels around the world [as shown by] satellite imagery from the European Space Agency,” the article said. “Readings from the ESA’s Sentinel-5P satellite show that over the last six weeks, levels of nitrogen dioxide (NO2) over cities and industrial clusters in Asia and Europe were markedly lower than in the same period last year. Nitrogen dioxide is produced from car engines, power plants, and other industrial processes and is thought to exacerbate respiratory illnesses such as asthma.”
Clearer skies are good news for everyone. Most importantly, asthmatics will breathe more easily. Secondarily, for those of us merely stuck at home and looking for a new hobby, stargazing has suddenly become a more viable hobby.
A major part of stargazing involves learning to see the sky at night. In order to learn how to do so, it’s imperative to keep the parts of the eye in mind.
“Your eye uses two kinds of light-detecting cells—cones and rods,” said Dr. Edward M. Murphy, Associate Professor, General Faculty at the University of Virginia in Charlottesville. “The cones, which can see in color, are concentrated in the center of your eye, whereas the rods are mostly outside of the central area. Rods can’t sense color but they’re much more sensitive to faint light.”
According to Dr. Murphy, at night, we rely mostly on our rods for vision, and for some reason they’re far less sensitive to red light than white. If you wish to use a star chart or simply wish to see where you’re walking at night, he recommended using a flashlight with a red filter to preserve your night vision. Dr. Murphy said you can either buy one at a store or place red cellophane over the end of a normal flashlight.
When looking at the stars, you’ll actually see them better if you don’t look directly at them.
“Since the more sensitive rods are not in the center of your eye but off to the side, overt your vision to focus the light on these more sensitive rods,” Dr. Murphy said. “Averted vision can also be used with a telescope or binoculars to make faint objects more noticeable. When looking through a telescope or binoculars, don’t stare right at an object; look a little to the side.
“When you look a little to the side, the light will be focused on your more sensitive rods and the image, the object, will be easier to see.”
Measuring the Sky
Since most of us aren’t knowledgeable on the distance between Earth and each of the celestial bodies we can see, stargazers often navigate based on those bodies’ positions in the night sky, beginning with the fact that a circle is separated into 360 degrees.
“A degree is a fairly large unit of measure, and so astronomers have divided a degree into 60 minutes of arc, which we usually abbreviate arcminutes,” Dr. Murphy said. “That’s even fairly large, so astronomers have divided an arcminute into 60 seconds of arc, called an arcsecond. That means if there are 60 seconds in a minute, 60 minutes of arc in a degree, there are 3,600 seconds of arc—or 3,600 arcseconds—in one degree.”
If that seems like a lot, it is. Fortunately, there’s one incredibly easy tool we can use to measure these angular differences in the night sky, and we all already have it. It’s our hand.
Dr. Murphy said that our finger is about one degree across. Additionally, when we make a fist and hold it at arm’s length, the fist is about 10 degrees across. When we stretch our hand out wide, the distance from the tip of the thumb to the tip of the pinky is usually close to 20 degrees. Of course, we don’t all have hands the same size, but there’s a reason why this measuring tool still works.
“This works well for most people because those of us with large hands tend to have longer arms, and so it appears about 20 degrees in the sky,” Dr. Murphy said.
Anyone can get online and search for star charts that pertain to their part of the world at any time of the year. Adding in a filtered flashlight and a steady hand can lead to discovering wondrous sights in clear skies, breaking up the monotony of being stuck at home during a viral pandemic lockdown.
Dr. Edward M. Murphy contributed to this article. Dr. Murphy is Associate Professor, General Faculty at the University of Virginia in Charlottesville. He earned his bachelor’s degree in Astronomy from the University of Illinois, Urbana-Champaign, and his Ph.D. in Astronomy from the University of Virginia in 1996.