Eye-popping Venus, low-riding Mercury and stealthy Saturn will all make appearances among the bright objects in September's night sky, and this day-by-day description shows how to find them.
This month, Mercury might be glimpsed very low
Eye-popping Venus, low-riding Mercury and stealthy Saturn will all make appearances among the bright objects in September's night sky, and this day-by-day description shows how to find them.
This month, Mercury might be glimpsed very low near the west-southwest horizon while Saturn gets lower each evening in the southwest at dusk. Meanwhile Mars, Jupiter and Venus have crossed into the morning sky, but only dazzling Venus is readily seen at dawn as it rapidly rises higher each morning. It hovers just to the upper right of the waning crescent moon in the wee hours of the Sept. 10. Mars is in the general vicinity, although it glows only a fraction as bright as Venus. During the second week of September, Jupiter appears against the bright morning twilight and becomes easier and easier to see during the latter part of the month. This video explains which planets are visible in the September night sky.
Remember, you can use your clenched fist at arm's length — equal to roughly 10 degrees of the night sky — to measure off angular distances and locate planets on display. Here's a look at when to see the brightest planets in the September night sky, if local weather conditions cooperate:
Sep. 4: About half to three-quarters of an hour after sunset, scan the horizon just south of due west to spot the planet Mercury. Mercury is 27 degrees east of the Sun this evening, the furthest it will get in 2015, but it is still difficult to see from northern latitudes as it sets in bright twilight less than an hour after sundown. Binoculars will be needed to see it. Farther south, Mercury sets in a darker sky and is visible to the naked eye, at least early this month. Mercury will pass between the Earth and the Sun, a condition called inferior conjunction, on the night of Sept. 30. [Best Stargazing Events of September 2015 (Sky Maps)]
Sep. 10: Venus is rising — or might we say "erupting" — into view along the eastern horizon at the break of dawn at the start of the month; it comes up earlier in a darker sky as each day passes. It will shine at its greatest brilliance (an eye-popping magnitude -4.8 on astronomers' brightness scale, which is 23