Dew forms when the temperature of your telescope’s glass or exposed surfaces drops below the dew point—the temperature at which air becomes saturated and water vapor condenses into liquid droplets. This usually happens on clear, calm nights when your telescope cools faster than the surrounding air.
Key factors that encourage dew formation:
- Clear Skies: Without clouds, heat escapes rapidly from your telescope.
- High Humidity: More moisture in the air means more chance of condensation.
- Calm Winds: Still air allows cold pockets to settle around your optics.
- Material & Surface: Glass and metal cool quickly, making them dew magnets.
Recognizing these conditions helps you prepare to protect your telescope and avoid blurry views or damaged coatings.
