The Most Important Astronomy Tips, What can make or break observing the stars

It is important to bear in mind multiple factors that could affect your next observations of the night sky. Everything from obscured stars to hazy photographs is amongst what could go wrong without considering these.

Moonlight. Skyglow. Clouds. This could all ruin an astrophotography session. Whilst nature’s power cannot be controlled, there are ways to prepare and choose the best nights to observe. Before being disappointed by your next weather or twilight defeat, there are six main factors that could make or break a good observation:

1. Light Pollution

Light pollution is what reduces the contrast between the sky and stars, rendering most of them invisible. Not only does urban lights hide them, it also ruins your eyes’ dark adaptation. This is a major issue for many naked-eye observers. Furthermore, city skyglow can create an unsightly haze in images. Light pollution is measured on the Bortle scale, 1 being the least light polluted and 9 being the worst, You can check your location’s light pollution on an online Bortle map. Some of the least light polluted areas of the UK include the very west tip of Cornwall, Northern Scotland and the Cambrian mountains in Wales.

2. Twilight

Whilst in the previous article, we talked about the beauty of nautical twilight photography, twilight can also reduce the sky’s contrast. It is important to wait until the night sky is truly pitch black. Particularly in long-exposure images, the sky can still appear much more blue and illuminated. To check when twilight ends, I recommend using a website such as TimeAndDate.

3. Moonlight

The Moon actually poses a myriad of problems for astronomers, and many wish it never existed in the first place! For most of the month, the sky is illuminated by moonlight. This makes deep-sky imaging next to impossible. Even with the brighter Andromeda Galaxy, moonlight makes it appear far more faint. Unless you want to observe the Moon itself, the best time to observe celestial objects is near/at new moon. I use Stellarium to check the duration of moonlight during the night.

4. Location

Whilst this many not be immediately considered, observing from an open area is always better. This allows you to observe celestial objects wherever they are in the sky. It is best to observe something when they reach the highest point in the sky, when they are closest to zenith, such as at culmination. As light passes through less of the atmosphere, the images are much better quality. Similarly, you may need an open horizon for something that has a very low altitude, like a comet.

5. Weather

An obvious factor that is key to check. Especially with British weather, sometimes the forecast is misleading. Cloud coverage can instantly ruin observation plans. I recommend (for UK observers) to use BBC Weather in combination with MET Office’s Cloud Coverage Map. BBC Weather usually has good predictions but a ‘clear sky’ can also mean a cloudy night. Whilst the cloud coverage map only predicts for the next 5 days or so, it is mainly accurate for showing cloud coverage in your area. If on the night clear skies are predicted but clouds are passing by, give it at least 10 minutes. I find that 70% of the time, the sky clears after a while if it is meant to. This is how I was able to photograph the Mars-Jupiter conjunction last year.

6. Atmosphere

The atmosphere is most steady in the early morning where the turbulent motion of air has decreased. Atmospheric stability can be measured on the Antoniadi Scale, where I is the most stable and V is the worst. For example, poor seeing conditions can make the moon appear blurry. This affects the ability of making sketches and good photographs. This isn’t something that can be well predicted but rather a factor that should be kept in mind.

These factors are key for observational astronomy, even for ancient civilizations millennia ago. Now, read the articles below for astrophotography ideas.