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How to Stargaze When Dealing With Light Pollution



By: Athena Tressler 

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As an undergraduate student studying physics and astronomy, one of my favorite hobbies is stargazing. I check to see when there are any celestial events, such as meteor showers, or when any of the planets, like Mars or Jupiter, are closer to us and are visible to the naked eye. The unfortunate thing that can happen is bad weather disrupting these events and stopping us from seeing them. However, due to the world's increasing reliance on artificial lighting, light pollution has made it impossible to see the night sky and has proven itself to be a big issue for astronomers. It's especially frustrating for those living near the city, and even in our neighbourhoods and parks, who want to see the beautiful Milky Way galaxy. All we see now in the night sky is a glowing haze from all the artificial lights, making it difficult for those who love to stargaze. Despite all of these issues, there is still a way to see the Milky Way galaxy and identify other constellations. This guide will help you understand what's causing light pollution, what astronomers are doing about it, and methods to follow in order to have a successful stargazing night, along with how to help reduce light pollution in your area.


What is Light Pollution?

Most people are aware of water and air pollution, but light pollution is often unnoticed, and is seen as harmless. Unfortunately, it has proven itself to be another problem on the rise for humans. Light pollution is caused by the excessive use of artificial lights. This mainly includes our streetlights in our neighborhoods and on the roads and highways. It also comes from houselights, large advertisements that you see in cities such as New York City with Times Square. Not only that, but in our cities, even when no one is working, most buildings leave an unnecessary amount of light on, which contributes to light pollution. 


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As shown above, these are the types of streetlights that will best help to reduce light pollution. The first one seen on the left is very common in most towns. While it provides a substantial amount of light to reinforce safety, it further contributes to the light pollution problem. Streetlights should have a cutoff, such as the full cutoff light, shown in the picture. A full cutoff streetlight still provides light, but doesn't cause skyglow. It's even better when they have timers that turn on when it starts to get dark and then turn off once it's morning. 


There are 4 different types of light pollution: Glare, skyglow, light trespass, and clutter.

 

Glare: Glare is the disproportionate amount of light that can cause distress to people. During the day time, when sunlight is reflected off of windows of a building or someone's windshield and reflects back into your eyes, this can cause discomfort. This also happens at night, with streetlights, especially when driving on the roads and being blinded by the excessively bright headlights. 


Sky glow: Sky glow appears as a yellow or orange haze that brightens the night sky. It gets reflected from the sky back to the ground, and when it's cloudy, this haze appears more frequently. People who live near a city see this constantly, and this blocks them from seeing any visible stars. 


Light trespass: The third type, it's the light shining outside of the area where it's supposed to shine. This is a common problem with the streetlights in our neighborhoods; unfortunately, this light shines into your bedroom, making it harder to sleep at night. This also happens when people leave their house lights on all night when they’re not needed. 


Clutter: Clutter is defined as an overwhelming concentration of light in an area, including bright billboards, neon signs, and advertisements. As previously brought up, this is seen in cities such as New York City with its Times Square, or Shibuya in Tokyo. 


Skyglow is the primary type of light pollution that restricts stargazing. Glare and light trespass disrupts your night vision, as well as your circadian rhythm. Over the past decade, another type of light pollution has emerged, and it’s not the bright streetlights or car headlights; it’s satellites. This type of light pollution is called Satellite glow, which involves satellite constellations that leave a multitude of bright dots in our night sky. This often gets mistaken for a star, but for those who are experts in knowing the constellations, they can see that this isn't a normal star. This problem has mainly arisen from the company Starlink. 


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This picture shows the trails of the Starlink satellites, which occurred while attempting to observe the comet C/2019 Y4. This image alone shows how Starlink is already causing problems for astronomers and astrophotographers. Due to their low Earth orbit, this has been interfering with observing the constellation. This photo was taken in 2020, when there were under 2,000 starlink satellites. Now in the year 2025, there are now approximately 8,094 satellites (Space.com). This has become a great concern that environmentalists and astronomers are raising awareness to. 


Sadly, for astronomers, finding the right places for observations has become an extra challenge. There is now a limit to seeing fainter celestial objects, including distant galaxies and others. For observatories, astronomers must travel to much more remote locations, often hours away from cities, to reduce skyglow. This has become increasingly costly, posing even greater challenges for astronomers. To choose the right location for our observatories, the best locations are those with high altitudes, dark skies, and stable weather conditions. Some of these places include Mauna Kea in Hawaii, Arizona, Chile, and BC Canada.


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This is the Mauna Kea Observatory, this is located on Hawaii Island, and is known to be the biggest observatory in the world. It sits on a volcano that is asleep, so we don't have to worry about anything for a while. What's so different about this observatory is it lies on an extremely dry mountain. This is good since they can measure the infrared and submillimeter radiation from the celestial objects. What's really good is because of the location it's in and its altitude, the skies are extremely dark, and no clouds. With an altitude of 4,205 meters, which is 13,796 ft above the ocean floor (source:University of Hawaii). These observatories need to be protected for astronomical research, and lets hope it stays that way. 


While it may be hard to find a place that is on a Bortle scale of 1 or 2, you can still stargaze in your area. There are many ways you can stargaze when living in an area that has a Bortle scale of 5 or higher. This is what you can do:


  1. Choose the right time and locations:

When stargazing, it's better to avoid the moon, since this can make it harder to observe the local stars. It's better to observe when the moon is below the horizon, in its waning or waxing crescent phase. It's even better when it's a full moon, it makes the sky even darker. 


To help you find the right locations, light pollution maps are a helpful tool to have. You can either download the light pollution map to your phone or access it directly in your browser at https://lightpollutionmap.app/. This website is suitable for use by people from any country around the world, wherever you live. When you enter the location you are in or are travelling to, the map will display the Bortle scale for that location, along with the weather conditions and whether you will be able to see the Milky Way. You can also download the app Stellarium, an app used for detecting visible celestial objects. 


You can also go to rooftops for a better view, or to your local park if possible. Or if you’d like to go on road trips, drive at least 30 minutes to 2 hours away from the local town/city. And when you go for these road trips away from the cities, make sure you're going the opposite direction from the city, so that you can avoid the skyglow. This is often what people do in my area. Since I live near Toronto, most people drive 1-2 hours away from the city, and go north to see the aurora borealis and other celestial events. 


  1. Let your eyes acclimate to the Darkness:

When stargazing, allow 20-30 minutes for your eyes to adjust to the darkness. This will help to make it easier to observe more stars. As your eyes are adjusting, what happens is your pupils get bigger, to allow more light to go into your retina. When you do this, it's best to avoid bright lights, especially from your phone. To make it easier, at nighttime, you can switch your screen brightness to night mode, which uses a warmer, orange light to reduce eye strain. And when doing this, whether it's in your backyard or when you're at the cottage, make sure to turn off your flashlights and any outdoor light nearby that is causing any disruption. 


  1. Using a blanket or a towel to shield your eyes from excessive light:

The first thing you should do is let your eyes get used to the darkness, and once you're done that, having a blanket is a great method to use to get all the darkness you can get. This takes out the remaining light that is shining around you. When you are viewing with your eyes or binoculars, put the blanket over the binoculars, to give you extra darkness. This is good to use when you are stargazing in your backyard, where there could be some skyglow or light trespass. 


  1. Choosing brighter celestial objects:

When stargazing for celestial objects, it’s better to choose the celestial objects that appear brighter compared to the others. This includes planets such as Jupiter, Saturn, Mercury, Venus, and Mars. You can visibly see these planets for the majority of the year, except for when it's daytime. It’s not possible to see all of these planets visibly at the same time, as their visibility fluctuates depending on their cycles. 


For Saturn, you can see it during the months May-July, and check in the east since this is where it rises, and when it sets, it goes to the west. This is due to Saturn being on the opposite side of the sun during these months. In the evening, look in the opposite direction of where the sun is setting; you should be able to see Saturn.


Venus is most visible during most of the year except for June. To spot it first, locate the Sun, and Venus should be more in the west. However, for this planet, you’ll most likely need a telescope to locate it. But even when there is light pollution, using a telescope will help you to find it, even if you aren't in a remote area. 


Mercury is more in the eastern part of the sky, and the best time to locate it is before dawn, when it's high over the horizon. April and May are the best months to see Mercury in the evening. And you can see it in the morning from October-November; this is for people in the Northern Hemisphere. 


Jupiter is located more in the western part of the sky, and the month of June is usually the best time to see it, since it's at its brightest. In the sky, it appears more white; you can usually use binoculars to see it. 


Lastly for Mars,  since it’s red, it’s easier to distinguish in the night sky compared to the other planets due to its colour. And is mainly visible to see throughout the majority of the year.  It’s easier to spot at midnight, since this is the time when it’s at its highest in the sky.


Mars is easier to see with your eyes rather than using a telescope.


And for nebulae, one of the brightest ones you can see is the Orion Nebula, which you can spot in the Orion constellation, more precisely in the south of Orion’s belt. 


So, even if you are in an area where you can visibly see the Milky Way, you can at least observe other celestial objects. 


  1. Use the Bortle Scale:

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The scale shown above is known as the Bortle Scale. This scale is used by amateur astronomers and astrophotographers, helping them to determine their sky quality before observing. It ranges from 1 to 9, with 1 being the most natural dark sky and 9 being the most light polluted night sky. This helps astronomers compare the darkness at different observation sites and choose the best site for observing. From 1 to 4, the Milky Way isn't too hard to find in the night sky. However, after 5, it becomes nearly impossible to see the Milky Way with the naked eye. For the range 6-7 this is most common in suburban neighborhoods. Only a few stars are visible here. As already mentioned above, to see what the bottle scale in your area looks like, you can use this app: Light pollution map. This can be used on the browser, or you can download it on apple and android. This can be used worldwide, in whichever country you're living in. For example, I put my area, and it gave me the Bortle scale, and I got 9.0, so I definitely have to drive north at least 1-2 hours away to get a scale of around 4. 


  1. Using light filters for your telescope:

For your telescope, use a light pollution filter, an example is the Optolong L Pro filter. This is good for filtering out the skyglow, and is often recommended by astrophotographers. This captures amazing detail and has a dual band filter of 7nm, and also isolates wavelengths Ha and OIII (High Point Scientific). The Ha wavelength is the Hydrogen alpha wavelength, and its wavelength is around 656 nm, and the OIII is the oxygen III emission line, with a wavelength of 500 nm. These wavelengths are emitted from nebulae and this filter will capture this wavelength, especially when observing in areas with light pollution. This is a fantastic filter to use for your telescope, however it can be expensive. 


  1. If you don't have a telescope, you can use binoculars:

If you're a high school or post-secondary student, it can be hard to afford a telescope, especially because they are very expensive. You can get yourself a regular pair of binoculars, this is good enough to see star clusters. It's more preferable to get one where the large lenses in the front are around 40 mm, and have a magnification around 7x to 12x. A good one to use is the Nikon 10x50 Aculon A211. This one can be a bit pricey, but is cheaper than a telescope.



While it has become utterly frustrating to deal with this problem, astronomers have been standing up against light pollution, and Starlink. Not only that, they have been demanding better laws to be enforced to reduce this issue. An important organization facilitating this effort is the International Dark-Sky Association (IDA). This organization was founded in 1988 by astronomers David Crawford and Tim Hunter, who was a physician, but had a love for astronomy. Although this organization originated in the United States, it has garnered support from countries worldwide. They have brought awareness to the dangers of light pollution on humans, climate change, and how it's causing more problems for wildlife and their ecosystems. Thanks to this association, more people have learned and gotten involved. It shows that we don't need to wait for the government to do something. We can make changes when we work together. 


Tips to Reducing Light Pollution


Small actions can have a big impact on reducing light pollution, even one person can make a significant change. Here are some things you can do to help:


  1. Turning off unnecessary lights: 

At night time, people often leave their house lights on during the late night. While people may leave them on for security reasons, if it's not needed, it's best to turn it off. This will reduce light trespass in your neighborhood, and will reduce interrupting people's circadian rhythms. 


  1. Switch to warm yellow/orange light, replacing blue light:

Nowadays with the switch of LED’s, while they are more energy efficient compared to incandescents, they are mostly cool toned. For your outdoor lighting, it's better to use warm lighting, as it not only gives a nice warm ambience, it's dimmer due to its lower temperature, making it better for reducing light pollution. While cool light is mainly used in stores and workplaces, it's brighter and good for neon signs, the issue with it is that having too much cool light outside causes more light trespass. 


  1. Use LED’s instead of incandescent light:

This is more energy efficiency, but it also significantly helps with reducing light pollution. They are longer, offer greater quality compared to incandescent light, and with its energy efficiency it saves way more energy. So in the long run, money is saved and you have long lasting products. While most LED's use white light, you can also get warm colour LED’s for outside. 


  1. Put motion sensors on outdoor lights:

Motion sensors are good for turning off the outside lights when it's not needed. This is usually during the day time, and late at night when everyone's asleep. Not only do you save money, you also help reduce light pollution, and the birds and neighbors won't hate you. An example is in the winter time, since the sun sets earlier you can turn them on at around 5pm, and maybe have them off at around 11pm or 12 am. 


  1. Use shielded light fixtures for outdoor lighting:

Your outdoor lights don't have to light up everything outside the house, using a light fixture that shields any light going upwards towards the sky greatly reduces light pollution. You just need a light that points the light beam downwards toward the ground. This also reduces the amount of power needed, since the light is focussed more on one area, rather than having the light escape in all directions. 


Light pollution has been an issue that needs to be taken care of, thankfully there are many solutions, and enough people that are bringing awareness about it. And I hope you are more comfortable now with being able to stargaze in your area. Even if you often deal with bad weather and light pollution, there are many solutions. 


For more information about Light pollution, you can join organizations such as Dark Sky International https://darksky.org/ to reach out and advocate for efficient and environmentally friendly lighting. 



“Somewhere, something incredible is waiting to be known.” - Carl Sagan 






















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