I like to watch movements of the planets which bring them into close encounters, or conjunctions. Some conjunctions are at a time and position in the sky so images taken over a few days can show their movements. Such was the case June 2019. A big challenge to getting well-timed images is cloud cover. We have had too much of it.
This image is a composite of three evenings of images looking west-northwest at 9:30pm. The camera was on a tripod at the same spot framing two light poles. I cut and pasted the locations of Mercury and Mars from the images taken on June 7 and June 20 onto this image taken on June 11. The dates for each are labeled. Click here or on the image to embiggen in a separate tab.
Note that Mercury, in yellow highlight, moved toward the upper left between June 7 and 11. It moved farther to the upper left by June 20. Mars, in white, moved down to the right between June 7 and 11. It continued down to the right by June 20. I hoped to image the two planets on June 17 or 18 when they appeared very close together, the width of a full moon. But clouds happened.
The solar system dynamics of this conjunction are interesting but not intuitive. The videos below will help visualize their alignment. First, a computer simulation of the orbits of the inner planets shows them as viewed from above the Sun. Thanks to the excellent web site In-The-Sky by Dominic Ford for this graphic. You should explore his site.
The video begins on 7 June when I had my first clear view recorded in the photograph above. It advances to 11 June then to 17 June. The view is then tilted so it is very oblique to show the alignment of Mars and Mercury as seen from the direction of Earth. Notice that the plane of the orbit of Mercury is slightly tilted with respect to the orbits of the other planets. Mercury is also moving fast due to its orbit close to the Sun.
Time is advanced to 1 July. Mercury moves ahead quickly in its small orbit. Mars moves slowly across the sky in the distance. Notice that Venus is moving behind the Sun from our point of view. It will emerge as an evening object much later this summer and into the fall.
Using my desktop software, I recorded how Mercury and Mars would look if the sky views were always clear from my vantage point in Iowa at 9:30pm. You can see how close they appeared on 17 and 18 June. Too bad we had clouds. Actually, they were not physically close at all. Also, the tilted orbit of Mercury caused its curving path.