The Night Sky

The slideshow is an introduction to what can be seen in the night sky.

On clear nights away from city lights, one can see with the naked eye about 6000 stars as well as the moon, 5 or maybe 6 planets, nebulae, globular clusters, the Milky Way and 3 other galaxies.

The stars form 88 constellations. The brightness of heavenly bodies is described by their magnitude, ranging from magnitude 6 for those just visible to -1.4 for Sirius, -12 for the moon and -27 for the sun.

Because of the rotation of the earth, the stars appear to rotate around the north or the south celestial pole once every 23 hours and 56 minutes.

The sun appears to move around the stars completing a circuit once every year. The moon does the same in about 28 days.

Image: maxpixel.net