Soleil allows you to view current sunrise/sunset times from your terminal. Soleil uses the OS X Core Location framework to calculate your current position, so it requires OS X.
$ npm install -g soleil
Soleil uses suncalc for sunrise/sunset calculations and node-corelocation to find your current location. Suncalc is licensed under the BSD-2 Clause (Copyright 2014, Vladimir Agafonkin).