- Planétarium Rio Tinto Alcan
From August 28 to September 11, 2017
Mercury passed between earth and the sun (inferior conjunction) on August 26. The tiny planet reappears at dawn during the first week of September: using binoculars, look for it low in the east, 30 minutes before sunrise. Mercury rapidly becomes brighter after September 8; combined with the fact that it’s still pulling away from the sun’s glare, it becomes much easier to see with the naked eye. On the morning of September 10, Mercury passes about ½ degree from the star Regulus. On the morning of September 18, the thin lunar crescent will rest between Mercury and dazzling Venus higher above.
Venus is the bright Morning Star, shining above the eastern horizon at the end of the night and at dawn; Venus rises more than 2 ½ hours before the sun. On the morning of September 17, the thin lunar crescent will rest 7 degrees above Venus, and just 4 degrees below the dazzling planet the following day.
Mars gradually reappears in the morning sky: using binoculars, look for it at dawn, 30 minutes before sunrise, very low above the east-northeast horizon. From September 11 to 19, let much brighter Mercury guide you to Mars, as the two planets appear less than 3 degrees apart; minimum separation, barely more than ¼ degree, occurs on September 16.
Jupiter is getting closer to the sun and appears lower and lower in the sky at nightfall. The bright planet comes into view at dusk some 12 degrees high in the west-southwest, and then gradually descends toward the western horizon where it sets after 8:30 p.m. Bright star Spica shines with a bluish-white tint just a few degrees from the giant planet.
Saturn appears at dusk, some 20 degrees above the south-southwest horizon, and vanishes in the southwest after 11 p.m. The waxing gibbous moon will appear near the Ringed Planet on the evenings of August 29 and 30.