CalSky is a web-based astronomical calculator for Created by Arnold Barmettler, a scientific assistant at the University of Suez and the European Space Agency, it is available in English and German, with a calendar function and includes information on auroras, comets, tides, solar energy, lunar eclipses, planets, and satellite positions.

For example, use CalSky to observe "Tiangong 1", after entering the site, first set the location, click the red circle on the right to locate, click the Earth, you will see such an interface, it seems very complicated. But the rest can be ignored, according to the chart labeled settings will be good. The first step, in the box to fill in the name of your region (pinyin), for example, I will write "hongkou, shanghai"; the second step, click the "Start" button on the right, then the following google map will find You search the map of the region, and display out; third step, find your location on the map, double-click here, there will be a pop-up bubble box; fourth step, click the bubble box in the "Click here ". Next, the page will be refreshed again, wait for the refresh to complete, the location has been set up. What you need to do is to pull down to the bottom of the page and click the "go!" button in the red box.

Then, you will see the satellite list! Now Tiangong-1 is at the top of the list, it's easy to find, it's the "Tiangong-1"! However, after its position will gradually to the back of the line, because humans are still constantly launching new things, here you can set the observation time, generally will be the current time, you can ignore. The red line marked below, you intend to let this site to help you predict how long the time period. More detailed information can be accessed].