Minnesota Skies: June 2018

Our solar system is relatively flat with the Sun at the center and the orbits of the planets all lying within a few degrees of the plane of the solar system. As we watch from moving Earth, the Sun appears to move against the stars. Astronomers call this apparent path of the Sun against the background of stars the ecliptic. Since the solar system is flat, the other planets and our Moon also seem to follow near the ecliptic.

To see this apparent path, look at about 10:30 p.m. around mid-June. Venus gleams low in the west, Jupiter beams higher in the south and Saturn shines low in the east. Draw an arc through those three and you are following the ecliptic. Check it out still further as Moon follows that arc from June 16 near Venus to June 22 near Jupiter and on June 27 very near Saturn. The star chart in the June issue of Sky and Telescope shows this well. Keep in mind that Moon is much closer than the planets so these alignments are merely line-of-sight. More on the ecliptic here http://cse.ssl.berkeley.edu/lessons/indiv/beth/beth_intro.html

A few bright stars also lie along the ecliptic but they are much further away and have nothing to do with our solar system. To find those, start with Venus and move about 25 degrees left along the ecliptic to find Regulus, a star in Leo the Lion. Another 55 degrees along the ecliptic brings you to Spica in Virgo and after another 20 degrees you see Jupiter. Keep heading toward Saturn to find ruddy colored Antares in Scorpius and finally you Saturn and Moon align low in the southeast.