As our planet revolves around the sun, the sun appears to rise and set in different locations along the horizon and appears at different heights in the southern sky at noon. Twice during the year, the sun rises precisely east and sets precisely west. As seen from the equator at noon, the sun appears overhead. The sun never appears at the zenith, directly overhead, as seen from the mid-northern latitudes. The moment when the sun appears above the earth’s equator is know as the “equinox,” signalling a shift of seasons. From the autumnal equinox (northern hemisphere), the sun appears farther south, lower in the sky at noon, and rises and sets south of east and west, respectively, until the next equinox in March. The equinox occurs at 9:29 p.m. CDT on September 22.
This chart show the hours of daylight during September in the blue shaded area. (Click all images in this article so see them larger.) The red curve on the chart shows the daylight throughout the year. During the month, the Chicago area loses about 80 minutes of daylight. The loss of daylight during the month is the backwards of the increase of daylight from March 10 through early April each year,
||09/02/14 (6:11 a.m.)
||12:09 a.m. (9/25)
|09/08/14 (8:38 p.m.)
||7:04 a.m. (09/09)
||09/15/14 (9:05 p.m.)
||2:26 p.m. (09/16)
||09/24/14 (1:14 a.m.)
|Times are Central Daylight Time for Chicago, Illinois, from US Naval Observatory calculations. (For mjb)
Evening planets Mars and Saturn appear in the southwest as the month opens. On the diagram above, a nearly first quarter moon appears in the region near Antares. Mars and Saturn are to the lower right of the planet. The two planets are about 5.5 degrees apart.
By mid-month, the annual track of the Earth around the sun places the view lower in the southwest. Mars is moving east and by September 15, it is about 13 degrees east of Saturn and 9 degrees west of Antares. Watch Mars approach and pass Antares during the remaining days of this month.
Mercury skirts along the western horizon during bright twilight during the month. Use binoculars to look for it low in the west-southwest on September 21 when it is less than 1.5 degrees from Spica
Late in the month, Mars passes the star Antares. While the pair appear to be close, within about 3 degrees of each other, Antares is over 25 million times farther away than Mars. Mars shines by reflected sunlight and Antares is shining as a very distant star. While it appears small in our sky, Antares is large enough to cover the orbits of the inner planets in our solar system. The chart above shows the passing of the planet and the star,along with the appearance of the crescent moon.
Sometimes Antares is known as the “Rival of Mars” because it has nearly the same color and brightness. The Greeks knew Mars as “Ares,” their celestial manifestation of their god of war. So Antares can be interpreted as “Rival of Mars,” “The Opposite of Mars,” or “Not Mars.” Antares is not Mars.
Venus, the brilliant Morning Star appearing in the eastern predawn sky, is rapidly disappearing into the glow morning light this month. On September 1, Venus rises 1 hour, 15 minutes before the sun. By month’s end, it rises merely 34 minutes before sunrise. The planet passes superior conjunction, on the far side of sun, late next month and moves into the evening sky. For more about Venus as a morning star, see this article.
Early in September, Venus and Jupiter are over 15 degrees apart and the separation grows about 1 degree — twice the apparent size of the full moon — each day. The chart above shows them on the morning of September 2. Find a clear horizon to see Venus.
Venus passes the star Regulus in bright twilight on the morning of September 5. As the diagram above indicates, the pair appear low in the sky. Find an observing spot with a clear eastern horizon. Binoculars will help with the view.
As Venus disappears into the sun’s glow, Jupiter reigns as the bright Morning Star for the the remainder of 2014. It shines in front of the dim stars of Cancer. On September 1, it rises in the east-northeast at 4 a.m. and is about halfway up in the eastern sky as dawn approaches.
The crescent moon is near Jupiter on the morning of September 20. The pair is separated by about 6 degrees.
On the chart above, the planets visible without a telescope are shown along with Earth in their respective orbits around the sun as seen far above the solar system on September 15, 2014. The planets move in a counterclockwise motion. The line between the sun and Earth indicate time, noon and midnight. Venus and Jupiter appear on the morning side of the line. Venus is approaching the “noon” line indicating that it is moving into the sun’s bright glow becoming invisible to us. Mars, Saturn and Mercury are in the evening sky. Mercury always appears near the timeline making it difficult to view. From Earth, it never appears in the midnight direction.