Observing Astronomy Under Cloudy Skies : The Challenges

 

Last Saturday night, 29 March, 2025 I went to Kuala Selangor with my family to have dinner at a restaurant called Jeti (Jetty) Restaurant in Kuala Selangor.  After dinner we drove to another place called "Firefly Park Kuala Selangor" 9.8 km away to see fire flies along the banks of Selangor River. The fireflies, also called lightning bugs or glow worms or lampyridae, belong to a family of elateroid beetles with more than 2,000 species. 

It was a disappointment as there were just three or four bushes along the river banks where these lightning bugs emit their abdominal mating lights. This was in marked contrast with what I saw in the 1980s when I went there as a life member of the Malaysian Nature Society when the entire banks on both sides were flickering with lights by these insects.

 Anyway, the whole area was almost pitch dark which would have given me an opportunity to do some astronomy - an area I am more interested. But it was not. The sky above neither was dark nor clear. It was covered uniformly by a white sheet of darkened clouds spread out throughout the sky. There wasn't seen a single star above. This gave me a thought of writing a small article on conducting astronomy under a cloudy sky.

Star gazing under cloudy nights can be quite challenging, as clouds significantly obstruct our view of celestial objects. However, there are a few methods and tools astronomers and enthusiasts can use to maximize their observations even when the sky isn't completely clear. One of them is Infrared and Radio Astronomy.  While most amateur astronomers use visible light to observe celestial objects, professional astronomers often use infrared or radio telescopes, which can penetrate clouds better than visible light. However, these are typically not accessible to amateur astronomers due to their size, complexity, and cost.

Unfortunately, there isn't a specific filter that can be used to see stars through thick clouds, as most filters are designed to enhance contrast or block specific wavelengths of light rather than to allow visibility through thick clouds. However, if there are thin clouds or some breaks in the clouds, a light pollution filter might help enhance contrast against a cloudy sky.

Using a telescope with a camera is another way.  Some astro-photographers use long-exposure techniques to capture images of celestial objects. If there are brief moments where the clouds part, a camera attached to a telescope can sometimes get a shot of stars. Post-processing techniques can help bring out details in images captured under suboptimal conditions.

Observing through less dense clouds is possible.  Sometimes, thin or wispy clouds can allow for some visibility of celestial objects. In those instances, we might still be able to see bright stars or even planets. Using binoculars can sometimes help with this as well.

Satellite passes can often be seen. While this doesn't involve direct observation of celestial bodies, satellites such as the International Space Station (ISS) can be seen moving across the sky and often appear brightly even through thin clouds. I have often seen them. They move quite fast across the sky.  There are apps and websites that can help us find out when to watch for these events.

There are also live observations and online resources if skies are cloudy,  Many observatories offer live feeds or streaming events featuring telescopic views of celestial events, which can be accessed right from home. Websites and mobile apps might also provide real-time updates on celestial events. But this is not as good as actually seeing them in clear skies.

Even if we cannot see the stars, studying star maps, using a planisphere, or utilizing stargazing apps can help us learn the positions of celestial objects. This knowledge can be useful for planning future observations when the sky is clearer.

Unfortunately,  weather patterns are influenced by humidity and temperature, and it's a common phenomenon in tropical regions like Malaysia.

In the tropics, warm air holds more moisture, and when this humid air rises and cools (due to cooler temperatures at higher altitudes), it condenses into clouds. This often results in frequent cloud cover, especially during certain times of the year, such as the monsoon season.

Conversely, in many colder regions, especially in places like deserts, the air tends to be much drier and less humid. With lower humidity, there’s less moisture in the air to form clouds, leading to clearer skies. That’s why we often see vibrant night skies in those areas.

While cloudy weather can be a challenge for stargazing, it can also create interesting atmospheric conditions and beautiful cloud formations. Plus, tropical locations often have stunning natural landscapes and rich biodiversity, providing other opportunities for exploration and appreciation of nature.

If we ever find ourselves looking for ways to observe the night sky despite the clouds, consider looking for astronomy clubs, if any in Malaysia, or  the National Planetarium in Kuala Lumpur  that might sometimes offer access to telescopes or group viewing nights when conditions are better.

In summary, while there is no substitute for clear skies in astronomy, certain techniques and tools can help us maximize our observations during less-than-ideal conditions as in my case  in the firefly park in Kuala Selangor last night.