Early-rising skywatchers in the Northern Hemisphere cannot fail to notice dazzing Venus low in the east an hour before sunrise. For observers in Western Europe around the latitude of the UK, the brightest planet rises in the east-northeast about 2¾ hours before sunrise by the middle of this month. But Venus is not the only planet visible in the eastern sky as dawn twilight asserts itself. If you can find an unobstructed view with a level horizon, then you could glimpse Mars and Mercury too.
Mercury and Mars get close on 16 September
Although sadly unobservable from the British Isles, Mercury passes just 3.3 arcminutes (or 1/20th of a degree) north of Mars at 19h UT on Saturday, 16 September. One needs to be in Micronesia in the Western Pacific (Guam, for instance) to get the best naked-eye views of this close planetary pairing 30 minutes before sunrise on 17 September (local date).
On Monday, 18 September, observers in the British Isles can see Venus close above the thin, waning crescent of a 27-day-old Moon about an hour before sunrise, as depicted in the illustration above (use our interactive Almanac to calculate the time of sunrise from your location). Shining at an unmissable magnitude -3.9 and presenting a tiny 11.6 arcsecond-wide, 88 percent illuminated disc in a telescope, Venus lies 3 degrees above the slim lunar crescent on the morning in question.
Both Venus and the Moon will fit within the same field of view of typical binoculars with the bonus of magnitude +1.4 Regulus, the brightest star in the constellation of Leo, between the planet and lunar crescent in the growing dawn twilight of 18 September. If you time it right, and your eastern horizon is level and clear, you might also glimpse magnitude -0.9 Mercury and magnitude +1.8 Mars separated by 1¼ degrees. With your binoculars, sweep 8 degrees (nearly the width of your fist at arm’s length) to the lower left of the Moon to locate first Mercury then much fainter Mars, but please — only attempt this before sunrise!