I don’t know if people know about this, but you can make an ADS-B receiver with a few things and see planes flying overhead.
What You'll Need
Raspberry Pi 3
(A Raspberry Pi 2 will work, as long as you have a Ethernet cable or WiFi dongle)
(I use a MicroUSB cable and an Apple USB Power Adapter)
A MicroSD Card (8 GB or larger) and a way to read/write files from your PC (NOT the Pi)
A USB Receiver
(I use an RTL-SDR, which is $20)
(An SMA male antenna will fit into the RTL-SDR. Here is one: http://amzn.to/2m6tbTQ)
Once you acquire the required materials, you will download PiAware onto your MicroSD card. While it is plugged in, you can change the Raspberry Pi’s settings. Then, just plug everything into your Pi and watch it startup. Next, on a different computer, open your router’s webpage and find the IP address of the Pi. Type this address into the bar at the top of your browser to see the data from the Pi. Viola! You can now see planes overhead using ADS-B.
For more info, you can go to this website: http://bit.ly/23cwt6V
Good luck, and have fun seeing planes fly above you.