Evening star
The evening star is the brightest star apart from the moon that emerges after sunset , in particular the planet Venus , if it is visible in the evening for about seven months in a 19-month cycle. If Venus was an evening star for months, it wanders past the sun for a few weeks - not visible in the night sky - and then becomes the morning star for six to seven months before it wanders behind the sun. Their time of appearance depends on the respective position to the sun: as an evening star with an easterly elongation , as a morning star with a westerly elongation (for the positions of the 2010s see the list of Venus positions ).
In the event that the planet Venus is visible, the morning star and the evening star refer to the same changing star , which was previously not known. In Greek mythology the evening star is called Hesperos , but is less important there than the morning star ( Phosphorus ). Even after the identity of both celestial bodies with the planet Venus had become apparent, the separation into two mythological beings was maintained in antiquity .
In addition to Venus (maximum magnitude −4.67 mag), the lower planet Mercury (max. −1.9 mag) can appear as an evening and morning star, but this is seldom the case because of its proximity to the sun, and for each one hour maximum. In the ideal case, its brightness is only minimally higher than that of the brightest visible fixed star ( Sirius A −1.46 mag) and also significantly below that of the outer planets Mars (max. −2.91 mag) and Jupiter (max. −2.94 mag) ), the visibility of which is only temporarily linked to the period of twilight and which can be visible throughout the night if the position is opposite to the sun. The visibility of the ring planet Saturn (max. −0.47 mag) is only temporarily linked to twilight, and then it can at best be the brightest star if none of the others mentioned is visible.
Web links
- World of physics: what are evening and morning stars?
