The eccentricity of Earth's orbit is a measure of how elliptical or circular the orbit is. It is a dimensionless number between 0 and 1, with 0 representing a perfectly circular orbit and 1 representing a highly elliptical orbit.
The eccentricity of Earth's orbit can be determined through the use of Kepler's laws of planetary motion, specifically the third law which relates the period of a planet's orbit to its distance from the sun. By measuring the distance between Earth and the sun and the time it takes for Earth to complete one orbit, the eccentricity can be calculated.
The current eccentricity of Earth's orbit is approximately 0.0167, meaning that Earth's orbit is very close to being circular.
The eccentricity of Earth's orbit does not have a significant effect on the seasons. The tilt of Earth's axis and its orientation towards the sun is the primary factor that determines the changing of seasons.
Yes, the eccentricity of Earth's orbit has changed over time. It varies cyclically over a period of about 100,000 years. This is due to the gravitational influence of other planets in the solar system, primarily Jupiter and Saturn, causing slight variations in Earth's orbit.