Astronomy & Light Pollution
For thousands of years, people from every part of the world have been studying the stars. Ancient Egyptians and Babylonians to notable astronomers like Galileo and Carl Sagan have looked to the stars to try and understand our place in the universe and how it all works. As the world’s oldest science, astronomy has captivated the minds of many. The hundreds of objects that have been seen in the night sky since ancient times, like planets, stars, and galaxies, have given people the foundation to research and learn. Today’s Astronomers would not know as much as they do without the study of these objects. But with light pollution increasing at a rate twice as fast as the world’s population, dimmer objects are vanishing from our view and studying astronomy, as an amateur or professional, is getting harder.
Impact on Astronomy
Observational astronomy takes place under light polluted skies. If you were to go outside on a clear night in your neighborhood, it’s likely that you would be able to see most or all of the Big Dipper and handfuls of bright stars or planets. What you likely won’t see is the Milky Way. As light pollution increases, skyglow from unshielded lights make the night sky brighter and obscures the Milky Way from view. The 2003 power outage in the Northeastern United States shows the impact light pollution has on our view of the stars and Milky Way. Before the power outage, a few stars can barely be seen above the house, but during the outage the view from the same spot shows hundreds of stars and a clear view of the Milky Way.
When astronomers try to look at faint or dim objects through optical telescopes, like galaxies, nebulae, or star clusters, the same thing happens, and they get washed out by skyglow. These telescope images from Celestron of the nebula M57, show how the appearance of faint objects changes under light polluted skies compared to dark skies. Take a few seconds to look closely at the first image. How many stars can you see in the background? Do the stars look like pinpoints or are they hazy? How would you describe the nebula to someone not looking at the image? Now take a look at the second image and reflect on these same questions. As you can see, light pollution makes the stars and nebula harder to see and any details appear less clear. Try out this activity from Science Buddies to better see how light pollution effects the visibility of objects!
Another way that light pollution impacts astronomy is when astronomers try to study the spectrums of different objects, like stars, galaxies, and dust clouds. When an object produces light, scientists can split that light into different colored wavelengths. Instead of being a smooth rainbow, the spectrum of an object will be made of vertical lines that correspond to specific wavelengths and elements, like hydrogen (H) or iron (Fe). Scientists use these lines to figure out what the object is made of and, depending on how far the lines are shifted to the right or left, how fast it is moving toward or away from us. The lights from cities and towns also create spectrums and can interfere with the spectrum of objects in space. So, when astronomers try to study spectrums taken under light polluted skies, they have to try to separate which lines are from light pollution. This is tremendously hard to do. Astronomers encourage people and places to use sodium vapor lights instead of other lights because they only have two lines in their spectrum and make studying object spectrums easier.
Tips for Star Gazing
Although light pollution is widespread in most places, there are still ways that you can make the most out of any star gazing experience, with or without a telescope. Having good lighting habits of using fully shielded, warm toned lights only where needed and turning them off or dimming them when not in use, is an important step to decreasing light pollution. However, many individuals and places are not taking these steps, so here is a list of ways to make the most out of your backyard’s night sky right now.
Turn off as many outdoor lights as you can and find a place to sit outside where you are not looking at or exposed to any other lights.
If you cannot find a place where you’re exposed to other lights, find the darkest spot possible and try wearing a hat, blocking the light with your hands, or going to a local park/dark sports field.
Wait about 30 minutes for your eyes to adjust to the dark without looking at smartphones. Your eyes will be more sensitive to dimmer light once adjusted.
Wearing blue light glasses or sunglasses inside for a few minutes before going outside will help the process.
If you are using a star finding app on your phone, make the screen as dark as possible before going outside to keep your eyes adjusted to the dark. If your phone is too bright, your eyes will need to re-adjust for another 30 minutes.
Light from the moon can also make it hard to observe, so wait until the moon sets or it’s a crescent or new moon.
Dress warmly! Even in the summer, sitting outside at night can get chilly, so bring a jacket and pants just in case.
Get in touch with or join your local astronomical society, like the New Hampshire Astronomical Society, to learn more through their public events like sky watches or star parties!
Sources:
https://www.iau.org/public/themes/light_pollution/
https://cescos.fau.edu/observatory/lightpol-astro.html
https://www.darksky.org/light-pollution-and-the-beginner-astronomer/
https://link.springer.com/chapter/10.1007/978-3-642-74020-6_31
https://www.rasc.ca/sites/default/files/LightPollution-EffectsonAstronomy.pdf
http://adsabs.harvard.edu/full/2000MmSAI..71...11C
http://www.nhastro.com/skywatch.php
https://astronomyrookie.com/48-tips-for-becoming-an-awesome-amateur-astronomer/
https://www.sciencebuddies.org/stem-activities/constellations-light-pollution#summary
By Amanda Leith
