Stellarium

Stellarium is an interactive map of the sky which allows you to “look” at the stars and the sky just like with a telescope. A bit like GoogleEarth for the sky. It’s packed full of features:

• more than 210 million stars
• constellations and illustrations of constellations for more than 20 different cultures
• realistic Milky Way
• eclipses, sunrise and sunset
• the planets and their satellites
• comets
• images of weather galls (complete Messier catalogue)
• supernovae
• customisability

and a hundred other things. Just download and install. It will ask you for your preferred language during install:

But if you missed that, just go to the settings and pick Gaelic:

Not even a restart required!