A day is defined as the time it takes a planet to make one rotation on it's axis.
BY watching the sky, the priests learned about Astronomy and developed a 365-day calendar
Astronomy
The autumnal equinox.
Assuming that this is a question about Astronomy, the answer would be "day" or, more exactly, "sidereal day".
In astronomy, a day is the time it takes for a planet to rotate once on its axis. A month is the time it takes for the moon to orbit around a planet. A year is the time it takes for a planet to orbit around its star.
In physics and astronomy, a star is a huge globe of plasma that emits its own radiation.
In astronomy, a cluster is a large group of celestial bodies such as stars or galaxies.
Rotation is the circular motion of a body around a central axis.
BY watching the sky, the priests learned about Astronomy and developed a 365-day calendar
A galaxy is a vast self-gravitating structure of interstellar matter, energy, and forces.
A star is any hydrostatically stable plasma that generates heat and electromagnetic radiation by nuclear fusion.
The smallest day in reference of Astronomy and Geography is 23rd day of every December.
Astronomy
The autumnal equinox.
The NASA astronomy picture of the day is a daily picture provided by NASA of something in space along with an explanation by an astronomer. The NASA picture of the day can be found on NASA's website.
An orbit is the circular or elliptical motion of one smaller body around another larger body due to gravitational attraction.
Astronomy would be a course to take solely on personal interest. Astronomy has very little practical use in day to day life. Astronomy itself can be a good course, depending on the professor, but depending on your major field of study it might not be practical to take.