Saturn visits Sagittarius

(2 June 2017) Sagittarius is one of thirteen constellations of the zodiac, and is currently, with Scorpio, the main constellation overhead during the evening. The zodiac is an area of the sky centered upon the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. In the tropics the sun transits Sagittarius between approximately November 23 and December 21.
Not only the sun, but also the moon and the planets ‘follow’ the ecliptic. Therefore the planets always, and only, can be found in any of the constellations of the zodiac. In this photo Saturn is ‘in’ Sagittarius. This constellation is interesting also because if we, from planet earth, watch it, we are looking straight into the center of our own galaxy, the Milky Way. The middle of the Milky Way consists of a big black hole, 25,000 light years away.
Saturn is much closer. It took light from the planet only an hour to reach us.

Technique
Camera on the tripod, 18 mm focal length. To avoid ‘star trails, which can easily form in the night sky photos because the stars ‘move’, the maximum shutter speed is 500/18= 27.7 seconds (the rule of thumb is 500 divided by the focal length). In this case I used 25 seconds, with maximum aperture (f/5.6) and high sensitivity (ISO 1,600). The trees were artificially lit up with a torch during the 25 seconds exposure.