Dynamics of Earth and the Solar System: Movements and Phenomena

The Solar System and Its Components

It consists of a single star called Sol, which gives this system its name, plus eight planets orbiting the star: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Plus a number of small bodies:

• Dwarf planets (Pluto, Eris, Makemake, Haumea, and Ceres)
• Asteroids
• Moons
• Comets

...and interplanetary space between them.

Earth Sciences and Geosciences

The Earth Sciences and Geosciences are all the disciplines that study the internal structure, surface morphology, dynamics, and evolution of Planet Earth. Earth Science is a special case of planetary sciences, dealing generally with the study of Solar System planets and respect.

Earth's Movements: Rotation and Revolution

The rotation occurs from left to right and takes 23 hours, 56 minutes, and 4 seconds to make a complete turn. The result of this movement is the cycle of days and nights.

At the same time as the Earth rotates on itself, it makes a trip around the Sun, which is known as translational motion (or revolution). This orbit takes 365 days, 6 hours, and 9 minutes, i.e., one year. The extra hours are combined into a single day, so every four years, the year is 366 days and is known as a leap year.

The Equinoxes

An equinox is the time of year when the days have a duration equal to the nights at all places on Earth, except at the poles. The word equinox comes from the Latin aequinoctĭum and means "equal night."

Equinoxes happen twice a year: around March 20 or 21 and September 22 or 23. These are the two times when the two poles of the Earth are found at an equal distance from the Sun, with sunlight falling equally in both hemispheres.

The Solstices

The solstices are those times of the year in which the Sun reaches its highest position in the southern or northern sky, i.e., maximum declination north (+23° 27') and maximum south declination (-23° 27') with respect to the Earth's Equator.

The Chandler Wobble and Precession

The Chandler Wobble is a small variation in the axis of rotation of the Earth, specifically a variation of 0.7 seconds in a period of 433 days. In other words, the Earth's poles move in an irregular circle of 3 to 15 meters in diameter, in an oscillatory motion.

This wobble is an addition to the precession of the equinoxes, a greater variation that requires about 25,000 years to complete.