In the first month of autumn, the night sky is dominated by the second largest planet in our solar system, Saturn. Already with nightfall you can see the ringed planet in the southeast in the constellation Aquarius. As one of the brightest stars, Saturn is easy to spot. The nearly full moon will pass south of the planet on the 27th. Saturn is gradually withdrawing from the morning sky. If it sets shortly after 6 a.m. on the 1st, it sinks below the western horizon line at 4 a.m. on the 30th.
The Dutch physicist and astronomer Christian Huygens first recognized in 1656 that the Saturn globe is surrounded by a free-floating ring. In 1671, the first director of the Paris observatory, Giovanni Domenico Cassini, discovered the division of Saturn’s ring into an outer and an inner ring. Finally, space probes provided images showing hundreds of individual rings. Saturn is sometimes called “Lord of the Thousand Rings”. In the meantime, rings have also been discovered around the giant planets Jupiter, Uranus and Neptune. But they are inconspicuous and hardly visible in terrestrial telescopes. The gigantic Saturn ring system has a diameter of 280,000 kilometers, which corresponds to two thirds of the distance between the earth and the moon.
It takes Saturn 30 years to orbit the sun once. Because the Saturn globe rotates very quickly, Saturn’s sphere is the most flattened of all the planets. The gas planet also has the lowest density of all planets – it corresponds to only 70 percent of the density of water. The sphere of Saturn would thus float in a gigantic water bath.
Attractive inclination
Saturn’s ring is currently only slightly inclined towards the earth, which makes it particularly attractive to look at with a telescope. A visit to an observatory is therefore always worthwhile. Saturn’s giant moon Titan can be seen with binoculars. With a diameter of 5150 kilometers, it is the second largest moon in the solar system.
Radiant Venus dominates the morning sky. It is by far the brightest planet in Earth’s sky. Our inner neighbor planet reaches its greatest splendor on September 19th. At the beginning of the month, the planet of the goddess of love appears over the eastern horizon at around 5 a.m. On the 30th they rise at half past three in the morning. On a clear, haze-free sky, Venus can be followed until sunrise. In the telescope, it shows a large, narrow crescent at the beginning of the month. Even the first telescope observers at the beginning of the 17th century recognized that Venus shows phases like the moon. A nice coincidence with the waning crescent moon occurs on the 11th around 5am.
Rarely does one have the opportunity to see the nimble and sun-near Mercury. This time he will be visible in the morning sky for a good week from the 20th. On the 20th it appears at about half past five in the morning sky just above the eastern horizon.
Mars remains invisible
Jupiter in the constellation Aries rises in the late evening. Shortly after 10 p.m., the giant planet will rise above the eastern horizon line. At the end of September, Jupiter will rise at around 8:15 p.m. The waning crescent meets Jupiter on the evening of September 4th. Mars has long since withdrawn from the evening sky and remains invisible.
The moon will pass the Pleiades, the seven stars in Taurus, on the 5th. It appears as a waning crescent. In the middle of the month, on the 15th, the new moon phase is reached at 3:40 am. Full Moon occurs at 11:58 am on the 29th in Pisces. A day earlier, the moon comes close to earth at 359,911 kilometers. It passes through its orbital point furthest from Earth on the 12th, 406,291 kilometers separating it from us.
In the fixed star sky you can see the Pegasus square high in the south-east. It is also called the Autumn Square. Because Pegasus, the winged horse of the poets, is the guiding star of autumn.
The Summer Triangle has clearly moved to the west. Deneb im Schwan is now almost at its zenith. Virgo and Scorpio have long since perished. In the southwest, Sagittarius is preparing to also leave the nocturnal celestial stage. Capricorn wanders the meridian deep in the south.
Ancient constellation
Aquarius follows Capricorn in the zodiac and now occupies the space in the south-east. Like Capricorn, it is one of the faint constellations that are difficult to make out in the brightened city sky. Aquarius is one of the oldest known constellations. This constellation is closely linked to the biblical legend of the Flood. Aquarius corresponded to the 11th sign of the Babylonian zodiac. The Babylonian month was nicknamed “the curse of the rain”.
A first magnitude star flickers far to the south. It’s Fomalhaut, brightest star in Southern Pisces, just risen. The name comes from Arabic and means something like mouth of the fish. At a distance of 25 light years, it is one of our Sun’s neighbor stars.
In the north-east the light yellowish capella shines in the Fuhrmann. The Big Dipper rolls along the horizon low in the northern sky while Cassiopeia, the celestial W, just rises high in the east.
The sun leaves the constellation Leo on the morning of the 17th and moves into the constellation Virgo, where it remains until October 31st. On the 23rd it crosses the celestial equator at 8:50 a.m. in a southerly direction, the autumnal equinox occurs. This is the beginning of the winter half-year. The intersection of the descending path of the sun with the celestial equator marks the beginning of the zodiac sign Libra.
