I'm trying to solve this task:

Why do periods of good evening visibility of the planets usually come in winter and spring, and morning ones - in summer and autumn?

Could somebody please explain what planet's visibility is dependend on and what it has to do with time of the year?

  • $\begingroup$ earthsky.org/astronomy-essentials/… and farmersalmanac.com/visible-planets-guide for info $\endgroup$ Aug 31, 2021 at 16:13
  • 2
    $\begingroup$ I think the premise is false. Although the Earth's orbital period is a factor, the synodic periods of other planets are independent of Earth's seasons. $\endgroup$
    – Mike G
    Aug 31, 2021 at 17:52
  • 1
    $\begingroup$ Maybe it has to do something with their declination? $\endgroup$
    – ALiCe P.
    Aug 31, 2021 at 18:06
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    $\begingroup$ There might be something to that in Mercury's case. $\endgroup$
    – Mike G
    Aug 31, 2021 at 18:38

1 Answer 1


For inner planets (Venus and Mercury) the best time for observation is west or east elongation. During east elongation (planet can be seen in the evening) the planet is located "in front" of the Sun in the sky. The planet is seen the best in winter and spring because the Sun's declination is increasing and the planet gets to be before Sun, in place where it only will come, a little higher and therefore is seen longer. The almost same thing happens during west elongation (the planet is seen in the morning). The best time is summer and autumn because Sun's declination is decreasing and planet moves "behind" the Sun and again it is a little higher above ecliptic.


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