Evening sky
The evening sky is understood by astronomers, nature and star lovers as the view of the starry sky in the respective season between dusk and a few hours after sunset .
In contrast to the morning sky , the evening sky offers a few fewer phenomena (including the shooting stars ), but is more easily accessible for most people to observe and offers more pleasant temperatures than after midnight.
Depending on location and time
Since the earth rotates almost 15 ° to the east every hour, the term evening sky cannot be clearly defined. The visible half of the sky depends largely on the geographical latitude and, moreover, shifts by about 1 degree every day. Because the earth does not rotate in 24 hours, but 4 minutes faster. But our time is based on the sun , which in turn moves every year - as a mirror image of the earth year - through the 12 constellations of the zodiac (see ecliptic ).
Nevertheless, the term is firmly anchored in astronomical parlance , but it is dependent on the date and place. As an example, two sections of the sky are placed side by side, showing the evening sky in winter and that in spring , each for Frankfurt am Main and 10 p.m. CET on New Year's Day and on April 1st .
The two images are also valid one month later if you choose 8 p.m. for February 1st and May 1st as the comparison time (which in May, however, corresponds to 9 p.m. CEST ).
When comparing the two sections of the sky, only the northern constellations - the " circumpolar stars " around the celestial north pole or the polar star - are the same, but rotated by 90 ° (6 hours or a quarter of the earth's orbit). This means that the right figure not only shows the evening sky in spring, but can also be seen a few hours after midnight in winter .
On winter evenings, the large winter hexagon slowly rises in the east and southeast - consisting of the 6 brightest stars of the constellations Carter, Taurus, Orion, Big or Small Dog and Gemini. By spring, this striking hexagon had shifted to the western sky and will set a few hours later (except for the star Capella im Fuhrmann, which is circumpolar).
The seasonal changes in the sky can also be seen in the well-known constellation of the Big Dipper : on winter evenings we have to look for it to the right of the North Star (in the northeast), while its counterpart, the big W of Cassiopeia, is on the left (in the northwest) . In the course of the night the Big Dipper climbs higher until it is over our heads after midnight. It appears to us in an equally steep position on beautiful evenings in spring - and because this position is unfamiliar for less experienced sky viewers, some people cannot find the constellation or only after a long search.
Sky of the seasons
See also
- Sky observation
- Moon phase (waxing moon)
- Evening star
- Evening first and evening last
- Regions of the world "towards evening" (direction)
- Occident
- daylight
literature
- The sky year . Sun, moon and stars in the course of the year . Franckh-Kosmos-Verlag, Stuttgart 2015, ISBN 978-3-440-13097-1 (published annually)
- Austrian sky calendar, Astroverein Wien (published annually)
- Stars and Space , "Objects of the Month" section. Spektrum-Verlag, monthly
- A. Rigutti, E. Albisetti: The great book of astronomy , p. 86 to 97 (star maps by season). Kaiser-Verlag, Florence and Klagenfurt 2004
- Rudolf Brandt et al .: Sky Observations with Binoculars - An Introduction for Star Friends. German publisher, 2006
- Himmelsvorschau.org: Current star map (for computer time)
