Track planets with a laser!
If you’d like to observe certain celestial elements, you could do research and search the sky manually. Or just create a system to do it for you!
This is exactly what Subham Paul has done using an Arduino Mega, a GPS module, and 3.5-turn-pan and 180-degree-tilt servos. The real-time tracking device can predict the position of planets, calculated using Kepler’s Laws.
Data about the celestial body is input into his setup and then precisely pointed it out in the sky with a laser. All of this, of course, is dependent on where the user currently resides, which is taken care of via the GPS module as well as an optional MPU-9250.
As you could imagine, this is naturally an involved project in concept and implementation. You can find an introduction and links to further build steps here.