The planetary lineup at dawn (minus the Moon) from September 12th. Image credit and copyright: Alan Dyer (AmazingSky.com).
Following the Moon and wondering where are the fleeting inner solar system planets are this month?
While Jupiter and Saturn sink into the dusk on the far side of the Sun this month, the real action transpires in the dawn sky in mid-September, with a complex set of early morning conjunctions, groupings and occultations.
First, let’s set the stage for the planetary drama. Mercury just passed greatest elongation 18 degrees west of the Sun on September 12th.
The action warms up with a great pre-show on the morning of Saturday, September 16th, when the closest conjunction of two naked eye planets for 2017 occurs, as Mercury passes just 3′ north of Mars. The conjunction occurs at 16:00 UT, favoring the western Pacific region in the dawn hours. The pair is just 17 degrees from the Sun. As mentioned previously, this is the closest conjunction of two naked eye planets in 2017, so close the two will seem to merge to the naked eye and make a nice split with binoculars. This is also one of the first good chances to spy Mars ...