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Monday evening the 25th
of August Mars and Saturn will be at their closest to one another as they are separated by less than 1o
. This occurs at 18 UT, 1 pm CDT. Both planets are moving eastward along their respective orbits with Mars (0.519o
per day) being closer to the Sun moving faster than Saturn (0.0334o
per day). For my time zone the closest approach will occur during the afternoon but by sunset the separation will not have increased by that much.
Using binoculars, or just your eyes, compare the apparent magnitude of Mars (0.59), Saturn (0.59), and Zubenelgenubi (2.75). This is a good example of how distance is the key to apparent magnitude. For solar system objects, (planets, moons, asteroids, comets), how much sunlight is reflected is determined by the overall apparent size of the object’s disk. In the case of Saturn its ring system spans around 200,000 miles and with an apparent size like that Saturn is able to reflect enough sunlight so that despite its greater distance from the Sun Saturn, at varying times during its orbit around the Sun, may appear as bright or brighter than Mars.
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.