Descopera cosmosul! In fiecare zi este prezentata o noua imagine sau fotografie a universului nostru fascinant, insotita de o explicatie scurta din partea unui astronom profesionist.
2005 July 14
Credit & Copyright: Peter Wienerroither (U. Wien)
Explicatie: (Edit) As the Earth spins on its axis, the sky seems to rotate around us. This motion, called diurnal motion, produces the beautiful concentric trails traced by stars during time exposures. In the middle of the picture is the North Celestial Pole (NCP), easily identified as the point in the sky at the center of all the star trail arcs. The star Polaris, commonly known as the North Star, made the very short bright circle near the NCP. Full circle star trails are pictured over Vienna, Austria. This image, a relatively short exposure followed by a digital trick, could not have been taken during a single night because 24-hours are needed for one full rotation, and the Sun is sure to dominate the frame at some time.
Autori & editori:
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NASA Official: Jay Norris. Specific rights apply.
Un serviciu al: EUD at NASA / GSFC
& Michigan Tech. U.