Earth Motions And Eclipses

The point in Earth's elliptical orbit where it is farthest from the Sun, occurring around July 4th at a distance of about 152 million kilometers.

The point in Earth's elliptical orbit where it is closest to the Sun, occurring around January 3rd at a distance of about 147 million kilometers.

The two times each year (around March 21 and September 23) when the Sun is directly above the equator, making day and night of equal length worldwide.

The two times of the year (around June 21 and December 22) when the tilt of Earth's semi-axis is most inclined toward or away from the Sun, resulting in the maximum or minimum day length.

Time measured by the actual position of the sun relative to the local meridian, varying slightly throughout the year due to Earth's eccentric orbit and axial tilt.

Time based on the motion of a fictitious 'mean sun' that moves at a uniform speed along the celestial equator to correct the irregularities of apparent solar time.

The difference between apparent solar time and mean solar time, resulting from the combined effects of Earth's axial tilt and orbital eccentricity.

The slow, conical wobble of Earth's axis of rotation with a period of approximately 25,800 years, altering the positions of the equinoxes against the background stars.

An apparent force resulting from Earth's rotation that deflects moving objects to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

The central, darkest part of a shadow where the light source is completely blocked by the occluding body, essential for total solar and lunar eclipses.

The lighter, outer part of a shadow where the light source is only partially blocked, resulting in partial eclipses.

An alignment of three celestial bodies in a straight gravitational line, such as the Sun, Earth, and Moon during eclipses or full/new moons.

A period of approximately 6,585.3 days (18 years, 11 days, and 8 hours) after which the relative positions of the Sun, Earth, and Moon recur, used to predict eclipses.

An imaginary line on the surface of the Earth that runs roughly along the 180° meridian, marking the boundary where each calendar date changes.

The orbit of every planet is an ellipse with the Sun located at one of the two foci, explaining why Earth's distance from the Sun varies between perihelion and aphelion.

A line joining a planet and the Sun sweeps out equal areas during equal intervals of time, meaning Earth travels fastest when closest to the Sun (perihelion) and slowest when farthest (aphelion).

Long-term climate changes on Earth are driven by cyclical variations in orbital geometry: eccentricity (100,000-year cycle), obliquity/axial tilt (41,000-year cycle), and axial precession (23,000-year cycle).

Any object or fluid moving horizontally across the surface of the Earth is deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere due to Earth's rotation.