The sky on the night you were born

Put in a date and the picture below is the sky you'd have seen looking up that night. It isn't drawn — it's worked out from how far the Earth had turned at that moment, star by star. Change the date and the sky really does turn with it.

The centre is straight overhead, the rim is the horizon, north is up — and east is on the left, because this is the view lying on your back, which is the mirror of looking down at a map. Sixty of the brightest stars are here, with a few shapes worth knowing (the Plough, Orion, Cassiopeia, the Summer Triangle). It is not a full catalogue: several thousand stars are visible to the naked eye. Drag the latitude down past the equator to see what the southern sky hides from the north.