A Stargazer's Guide to Big Bear
There’s a specific moment on the drive to Big Bear, just as you crest the final ridge and find yourself above the clouds, where the air itself seems to change. It gets thinner, crisper, and noticeably cooler. For many, that’s just the mountain air. But for stargazers, it’s the signal that you’ve successfully risen above the obscurring atmospheric soup of Southern California.
At 6,750 feet in elevation, Big Bear is more than just a resort town; it's a perfect Southern California astronomy destination. The altitude keeps it above not only the atmospheric turbulence of sea level, but also the light and air pollution of the cities, leading to night skies far darker and crisper than much of the surrounding area. There's a reason Big Bear is home to a world-class solar observatory. When the elevation is this high, you aren't just looking at the stars—you’re practically standing amid them.
Big Bear above a seas of clouds. Image Credit: Don Ramey Logan (CC-BY 4.0)
Dark Skies
The immediately apparent appeal to any stargazer about Big Bear is its dark skies. Big Bear ranges from a 4.5 to a 5.5 on the Bortle Scale. Created by John E. Bortle in 2001, the Bortle Scale is a nine-level scale that measures how much light pollution is washing out the night sky in a given location.
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Bortle 1: Absolute, pristine darkness. The kind of sky where the Milky Way is so bright it actually casts a shadow on the ground.
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Bortle 9: Inner-city skies. You might see the Moon and maybe some of the brightest stars, but that’s about it.
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Read more about light pollution in my article on the topic.
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More developed areas, like the Big Bear Village, typically sees a Bortle 5.5 sky. It’s still miles better than the city, but you’ll notice a light dome from the concentration of buildings and outdoor lights.
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However, the magic happens when you head just a few minutes out of town. The eastern end of the valley and the high forest roads often hit a Bortle 4. At this level, the Milky Way doesn't just look like a faint wisp, it shows intricate structure, dark dust lanes, and a brilliance that often surprises those seeing it for the first time.
A light pollution map of the San Bernardino Mountains from lightpollutionmap.app. The white is the completely light-polluted city of San Bernardino, while the red is latent light pollution from the city spreading into the mountains, and the green is where the sky starts to get dark again. Note that Big Bear City has light pollution of its own.
Big Bear as a community even values its dark skies enough to have launched a dark sky initiative, aimed to help residents, businesses, and visitors be properly equipped to preserve the fleeting darkness and curb the spread of light pollution.
If you’re heading out for some stargazing of your own, you might want to skip the brightly lit South Shore. Instead, look toward darker areas. Some of the best places to stargaze in Big Bear are:
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The North Shore (Fawnskin): Because it’s less developed, the surrounding light levels are significantly lower.
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Onyx Summit: At 8,400 feet, this is one of the highest points you can reach by car. In addition to its darkness, you’re so high here that the air is incredibly still, making for "steady" viewing through a telescope. (More on that coming up)
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Holcomb Valley: Deep in the forest and away from any paved roads, this isolated spot makes for great stargazing.
High Altitudes
When you stand atop Big Bear's peak, you aren't merely at a higher elevation; you've physically moved above a large portion of the Earth’s atmosphere. Air may seem invisible to you, but to an astronomer, the air is an obstruction that they have to peer through. The more air there is between your telescope and a star, the more distorted that star becomes due to atmospheric turbulence.
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By climbing to nearly 7,000 feet, you can leave behind about 25–30% of the Earth’s atmosphere (and nearly all of its heavy moisture and pollutants).
At sea level, light from distant stars has to fight its way through thick, heavy air filled with humidity, dust, and marine layer clouds. This causes atmospheric extinction, where the light of fainter stars is scattered and absorbed before it ever reaches your eyes.
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As a high elevation desert mountain, Big Bear has air that is remarkably dry and thin. This allows for transparency that reveals objects which are physically impossible to spot from sea level and allows greater clarity for everything else.
Stars are well-known for their twinkling. While it's a key attribute of our view of stars, twinkling is actually a big hurdle for an astronomer. That twinkling, scientifically known as scintillation, is caused by star light passing through turbulent layers of warm and cold air, creating distortions. It prevents a clear and crisp image of the stars.
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Because Big Bear is so elevated and the air remains relatively stable over the lake, the mountain experiences good seeing conditions with minimal twinkling. The stars stop dancing and start looking more like steady, piercing points of light.
The Big Bear Solar Observatory
For proof of Big Bear as an astronomy destination, you need look no further than the notable white dome on Big Bear Lake's North Shore. That's the Big Bear Solar Observatory, a world-class university-based observatory constructed in 1969, run first by Caltech and now by the New Jersey Institute of Technology. It's designed to leverage Big Bear's ideal conditions to study the Sun.
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The primary dome houses what used to be the largest optical solar telescope in the world, until a solar observatory in Hawaii took the record in 2019. It can resolves features on the Sun's surface less than 31 miles across, which is an impressive feat, given the Sun's 865,000 mile diamter and 93 million mile distance.
While dark skies don't really help a solar observatory, Big Bear's elevation does significantly. Additionally, the lake itself lends important assistance to the observatory, explaining why it was constructed out in the water. During the day, the heat from the Sun will be absorbed and then released by the ground, creating additional turbulence in the air and therefore more distortion. The water surrounding the observatory mitigates this effect. The deep lake, combined with Big Bear's elevation and Southern California's low humidity and cloud cover all work together to make Big Bear Lake one of the best sites in the world for solar observation.
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For any interested, the Big Bear Solar Observatory offers limited tours to the public. Visit their website for more information.
Big Bear Stargazing Tips
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Find an open area. Trees, hills, and buildings can get in the way of the sky. The best stargazing areas have a wide open sky.
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Dress in layers. Mountain temperatures can vary, even in the summer. Be ready for cooler temperatures during night.
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Drink plenty of water. The thin mountain air that helps astronomy also causes your body to lose water faster than normal. Staying hydrated also helps your eyes see better.
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Give your eyes a chance to adjust. Your eyes can take up to 30 minutes to fully adapt to the darkness. Faint light, like that of stars, can be difficult to properly see without letting your eyes first adjust to the dark.
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Use a red light. Traditional white lights ruin night vision and make it harder to see the stars. Try a red light instead so you can see where you're going without ruining your night vision.
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Download a sky map app. There are many apps available for free that will not only tell you where to look, but also what you're looking at. The apps are able to use your phone's compass and gyroscope to determine where you're looking.
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Consider binoculars. Even if you don't have a telescope, binoculars can be great for stargazing too.
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Check the Moon phase. If it's a full moon or close to it, the light from the Moon can make it harder to see the stars. New moons, and the week leading up to and after them, are the best times to stargaze.
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If you want a more detailed guide to stargazing, read my article on the topic.
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If you're serious about getting the best stargazing experience Big Bear has to offer, then consider booking a stargazing tour with Amid the Stars. You'll get access to our state-of-the-art telescopes and an expert guide to answer all of your questions and to show you everything you'd want to see. It's the perfect nighttime activity to add to your Big Bear vacation.
A comparison of the night sky under different Bortle levels. The difference is clear.
Image Credit: ESO/P. Horálek, M. Wallner (CC-BY 4.0)
The two telescope domes of the Big Bear Solar Observatory on Big Bear Lake.
Image Credit: Z22 (CC-BY 4.0)