Chapter 1
The Sky over Upper Austria
Which constellations you can see
When you look at the sky, you see almost a hemisphere above you - 180 degrees from horizon to horizon. Which part of the celestial sphere you see depends on the latitude of your location.
Lines of latitude, also called parallels, are imaginary lines that divide the Earth. They run east to west, but measure your distance north or south. The equator is the most well known parallel. At 0 degrees latitude, it equally divides the Earth into the Northern and Southern hemispheres.
What do you think, where Linz is located on the globe?
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The North Sky
At the North Pole ("90th parallel") you can see exactly the so-called northern hemisphere. The North Star, the north celestial pole around which the entire starry sky seems to revolve, stands vertically above you at the zenith. The celestial equator, as a projection of the Earth's equator onto the celestial sphere, runs exactly along the horizon and forms the limit of what you can see. All stars north of the celestial equator belong to the northern sky, all below it belong to the southern sky.
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Section of the sky over Upper Austria
With every degree of latitude that your position as an observer moves south, towards the equator, the visible section of the sky above you also shifts: you "look" latitude by latitude below the celestial equator - towards the southern sky. In Upper Austria you can see more constellations than in northern Germany. In Linz, for example at the 48th parallel, you are already halfway to the equator. The 42 degrees that you are from the North Pole, you can see "further" on the southern horizon. Conversely, 42 degrees have disappeared below the northern horizon: constellations that are more than 48 degrees away from the Polar Star rise and set with the rotation of the Earth. However, stars that belong to the southern sky also occasionally rise here: you can see all constellations that are a maximum of 42 degrees below the celestial equator at certain times of the year.
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Stargazing
Only the constellations that are less than 48 degrees (for Upper Austria) from the Polar Star can always be seen - every night. These are the circumpolar images like the Big Dipper that don't go down. Conversely, you can never see stars that are more than 42 degrees below the celestial equator: constellations like the Southern Cross are too close to the south celestial pole for us. For observers in the southern hemisphere, these are then circumpolar. They never open for us. That means, we never can take images of stars and constellations in Upper Austria from the southern hemisphere.
To get started, select a star map that aligns with your geographic location and the current time of year; the night sky changes with seasons and geographical positions. Modern star maps come in various formats, from traditional paper charts to digital apps that use augmented reality to overlay star information onto the live sky view. Whether you're using a printed atlas or a smartphone app, ensure your star map is up-to-date and accurate, as it will be your primary tool in unraveling the celestial tapestry above.
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Astroviewer
Circumpolar Constellations
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