Is there a place on Earth, where polar axis lies on the horizont and heaven equator is in zenit? If it exists, can I, in theory, see all the constelations available worldwide this night?

  • 2
    $\begingroup$ The situation you describe occurs any place on the equator, and you can see most of the stars over the course of a night. However, some stars are too close to the Sun, and won't be visible (some will set too soon after sunset, others will rise too soon before sunrise) $\endgroup$
    – user21
    Sep 21, 2015 at 18:02
  • $\begingroup$ @barrycarter thx, but is the Earth's equator coincide with the celestial one? I thought this point should be somewhere off the equator (actually it should be line not parallel to latitude lines)? $\endgroup$
    – blitzar787
    Sep 21, 2015 at 18:07
  • 3
    $\begingroup$ We define the celestial equator to coincide with the Earth's equator. There is no separate celestial equator. It's just the projection of Earth's equator into space. $\endgroup$
    – user21
    Sep 21, 2015 at 18:23
  • $\begingroup$ @barrycarter thx, now I got it. $\endgroup$
    – blitzar787
    Sep 21, 2015 at 18:32
  • $\begingroup$ @blitzar787 You may be aware that the invariable plane of the solar system is different however. This might be what you were thinking of. $\endgroup$
    – called2voyage
    Jun 21, 2016 at 16:29

1 Answer 1


With the axis of rotation of the earth matching the axis of rotation of the stars, and the equator of the earth matching the equator of the stars, any place along the equator would match what you have described. However due to closeness to the horizon, the polar-most stars wouldn't be visible. If you were able to get a hundred metres or so above the ground, with nothing in the surrounding landscape, you could see all of the stars in the sky over a year's time.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .