The sky in September
Lunar eclipse coincides with increased risk of disaster
31.08.2024, 11:40 a.m.
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The September sky will see a partial lunar eclipse. A special constellation increases the risk of natural disasters. The planet Neptune will be visible in the starry sky all night and the autumn equinox will occur.
September will have a special spectacle in store for the night sky with a partial lunar eclipse. On September 18, the full moon will enter the Earth's penumbra and pass through the umbra. However, at the middle of the eclipse at 4:44 a.m., only about nine percent of the moon's apparent diameter will be hit by the Earth's umbra. The moon's northwest calotte will appear in a dark, reddish light. The moon will enter the umbra at 4:12 a.m. About an hour later, at 5:17 a.m., the moon will leave the umbra again.
On the same day, the moon will also come closest to Earth. It will be 357.286 kilometers away from us. The coincidence of the full moon and the proximity to Earth will lead to spring tides on the coasts. Earthquakes and volcanic eruptions can also be triggered during these days. The new moon will be reached on September 3rd at 3:56 a.m. Two days later, the moon will be 406,211 kilometers away from Earth.
Venus is slowly becoming the evening star again
Venus begins its evening star period. It is not particularly conspicuous yet. At dusk it can be seen just above the western horizon. It sets ten minutes before 9 p.m. On the 5th, the evening star is visited by the narrow crescent of the waxing moon.
Mars becomes a conspicuous star in the second half of the night. It moved from the constellation of Taurus to Gemini on September 5th. Jupiter in the constellation of Taurus shifts its risings to the late evening hours. On the 1st, Jupiter rises a quarter of an hour before midnight and on the 30th at 10 p.m. It is the brightest planet in the night sky, because Venus sets in the west before it rises. The waning crescent moon passes north of Jupiter on the night of September 23rd to 24th.
How Neptune was discovered
The sky view in September 2024.
(Photo: dpa)
Saturn will be in opposition to the sun in the constellation of Aquarius on the 8th. The ringed planet will rise at sunset, reach its highest position in the south shortly after midnight and set in the morning. On the day of the opposition, Saturn will be at a minimum distance from the earth: on this day, it will be 1294 million kilometers from the earth. The light will need one hour and 12 minutes to reach the opposition.
On the 21st, Neptune, the most distant planet in our solar system, will come into opposition to the sun in the constellation of Pisces. Since it is opposite the sun, it will be present in the starry sky all night long. Because of its distance from the sun, it can only be seen as a tiny blue marble through binoculars or a telescope.
Its existence was predicted based on deviations in the orbit of Uranus, which is further inward. In fact, the initially hypothetical planet was discovered on September 23, 1846, near the predicted location at the Berlin Observatory by Johann Gottfried Galle and Heinrich D'Arrest. It is 30 times farther away from the sun than the earth. No one can track a full orbit of Neptune around the sun, because Neptune takes 165 years to orbit the sun once.
Neptune has a diameter of 49,000 kilometers and is almost four times the diameter of the Earth, the fourth largest planet in our solar system. At this year's opposition, we are 4,322 million kilometers away from Neptune, a distance that light can travel in four hours.
Mercury offers relatively good morning visibility in the first third of the month. The planet closest to the sun is easiest to see from September 6th to 11th at the beginning of dawn, just above the eastern horizon.
Evening stars still summery
The fixed star sky in September 2024.
(Photo: dpa)
The evening starry sky still has a summery character. The orange-colored Arcturus can be found far to the west. The summer triangle of Vega, Deneb and Atair has moved a little to the west. In good visibility conditions, you can see a small star rhombus next to Vega, the main star of Lyra. The southwest corner star, the star on the bottom right from our perspective, was named Sheliak by the Arabs, which means harp. It is better known under the catalog name Beta Lyrae.
This star shows a dip in light every 13 days. It then shines 2.5 times dimmer than normal. This periodic change in light was discovered in 1784 by the 19-year-old amateur astronomer John Goodricke from York in England. For this and other discoveries, he received the prestigious Copley Medal from the British Royal Society in April 1786.
High in the southeast, the square of stars of Pegasus stands unmistakably. It is also called the autumn square, because Pegasus is the guiding constellation of autumn. The autumn square marks only a part of Pegasus, whose figure is much more extensive. Pegasus is a mythical creature, namely a winged horse that is said to help poets to take flights of fancy. When the hero Perseus cuts off the head of the terrible Gorgon Medusa, the winged horse Pegasus escapes from her torso. It flies through the air and lands on Helicon. Its hoofbeats as it lands cause the spring Hypocrene to spring up. Anyone who drinks from it will have wings in their imagination.
The Big Dipper is deep in the northwest, and Cassiopeia, the celestial W, is rising in the northeast. Arcturus, known as the Bear Keeper, is blinking just above the western horizon. It drives the Big Bear around the North Star. Arcturus is the main star of the constellation Bootes. The Greek name means cattle herder. Next to the constellation Bootes you can see a semicircle of stars. They mark the constellation Northern Crown. There are two eruptive variable stars in it, namely R CrB and T CrB. It is suspected that T Coronae Borealis (T CrB) will experience an outburst of brightness this year that will be visible to the naked eye. But that is not certain.
Autumnal equinox on 22 September
The sun moved from the constellation Leo to Virgo on the afternoon of September 16. The autumn equinox occurs on the 22nd at exactly 2:44 p.m., when the sun crossed the celestial equator and moved into the southern hemisphere of the firmament.
The point where the sun's descending orbit intersects the celestial equator is also called the Libra point, because it marks the beginning of the zodiac sign Libra. The Libra or autumn point is in the constellation Virgo.
