# Are there regions on Earth where at some point in time all the zodiacal constellations are on the horizon?

As you know, constellations are called zodiacal constellations along which the Sun passes, i.e., which the ecliptic crosses. Hence, it is necessary to determine where and when the ecliptic coincides with the horizon. At this moment, not only the plane of the horizon and the ecliptic will coincide, but also the poles of the ecliptic with the zenith of the inadir. That is, at this moment one of the poles of the ecliptic passes through the zenith. The coordinates of the north pole of the ecliptic (see figure):

δ_n = 90 ° -ε = 66.5 °.

α_n = 8 ^ h

and south, because it is at the opposite point:

δ_n = – (90 ° -ε) = – 66.5 °.

α_n = 6 ^ h

A point with a declination of ± 66.5 ° (the pole of the ecliptic) culminates at the zenith on the Arctic circle (North or South): h = 90 ° -φ + δ.

Of course, deviations from the polar circle by several degrees are possible, since the constellations are fairly extended objects.