Animation showing the movement of Sagittarius across the night sky as seen by an observer at the Equator (0º latitude). Only Sagittarius is shown in the animation; all other constellations have been omitted for clarity. The directions and altitudes shown refer to a star located on the ecliptic in central Sagittarius, indicated by a small yellow cross (+).
The constellation's direction and altitude (Alt) are shown at hourly intervals before Meridian Transit (-1 hour, -2 hours, etc) and after Meridian Transit (+1 hour, +2 hours, etc).
At the Equator, all celestial bodies rise and set vertically (at 90º to the horizon). One consequence of this is that the duration of the sunrise and sunset is shorter at the Equator than at any other latitude, twilight lasting only a short period of time, regardless of the season (it has often been said by equatorial explorers that "darkness falls quickly after sunset"). As is the case at other latitudes, the position of the sunrise and sunset on the horizon varies during the year, however at the Equator the length of daylight remains more or less constant throughout the year. This is why Daylight Savings Time (DST) is not observed in countries situated in Equatorial latitudes.
Scenery: Equatorial rainforest
Copyright Martin J Powell Jul 2008
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