It took me a while to feel comfortable with the Clear Sky Clock. Once I did however, it’s proven itself to be an invaluable imaging and observing tool. There are clear sky clocks for a large number of area. If there’s not one near you, you can request that one be created… for free!

The top row shows cloud cover for your site and surrounding area. This is pretty self explanatory. Darkest blue is clearest skies.  Transparency depicts the clarity of your atmosphere. Again, darker blue means clearer, more transparent skies. Lighter blues to whites indicate a lack of transparency. This is often the result of excessive moisture in the air. Seeing indicates the steadiness of the atmosphere over your site. This is a critical issue on nights where you’ll be doing some planetary observing and imaging. Good, steady seeing allows you to see the smallest details, and allows you to crank up the magnification more than on lesser nights.

If you can get a moonless night where the top 3 lines (cloud cover, transparency and seeing) are all dark blue,  you’re in for a really good night. Anyway… clear skies!