"Raspberry Pi Sense HAT for Astro Pi is an add-on board that fits perfectly on top of your Pi to provide you with plenty of sensing functionality. This means that the Sense HAT is great for learning about environmental conditions, particularly within space science. Sense HAT + Pi Board = Astro Pi!
What's on-board the Pi Sense HAT?
•8 x 8, 16-bit LED display that outputs sense data via shapes, icons and messages
•Inertial Measurement Unit (IMU) — essential for velocity, orientation and gravity measurement of a space craft, the IMU combines an accelerometer, gyroscope and magnetometer into one chip
•Barometric air pressure sensor
•5-button joystick that serves as an on-board keyboard and mouse"