Equatorial

Equator

The equator is the circle of latitude that divides Earth into the Northern and Southern Hemispheres. It is an imaginary line located at 0 degrees latitude, about 21,639 nautical miles in circumference, located halfway between the North and South Poles. The term can also be used for any other celestial body that is roughly spherical.

Tropics

The tropics are the region of Earth surrounding the equator, where the Sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. Because of Earth's axial tilt, the width of the tropics is twice the tilt. The tropics are also referred to as the tropical zone and the torrid zone.

equatorial

Adjective

1. Of, near, or relating to the equator.
2. Relating to the midline of any approximately spherical object.

Noun

1. A kind of telescope mounted so as to have two axes of motion at right angles to each other, one of them parallel to the axis of the Earth, and each carrying a graduated circle, one for measuring declination, and the other right ascension, or the hour angle, so that the telescope may be directed, even in the daytime, to any star or other object whose right ascension and declination are known.