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Seeing Forecast

The word 'seeing' in astronomical terms has nothing to do with a star's brightness, but refers to definition. The apparent brightness of a star is a measure of transparency, and is entirely different from seeing, though often confused with it. If you want to take a detailed look at the planets or our Moon you need to pick a night with good ‘seeing’.  Leaving aside telescopic faults, it may be said that the majority of poor definition is due to atmospheric disturbances.

The best time to get detailed views of the planets is when the atmosphere is steady from ground level up through the jet stream. Low or high level winds cause turbulence and the mixing of cold and warm air leads to blurring of the image.

The chart shows the wind at 15000 feet over Europe. It covers the next 10 days weather in 24 hourly increments. Ideally low wind speed is what you are looking for. This usually occurs under high pressure. Look for days when the UK is free of isobars.