Motions of the Earth Revolution Around the Sun

About the different motions of the earth that are going on around us astronomically and geologically including the earth's revolution around the sub.

MOTIONS OF THE EARTH

5. EARTH'S REVOLUTION AROUND THE SUN

The earth is following its elliptical orbit around the sun at 19 mi. per sec., or 68,000 mph. Astronomers define various types of years, but our familiar one is the tropical year, based on the seasons. Lasting 365 days, 5 hr., 48 min., and 46 sec., the tropical year is the time between the sun's passage through two spring equinoxes (e.g., Mar. 21, 1981, to Mar. 21, 1982). The fact that the tropical year does not contain an exact number of days has required the invention of leap year.