Does changing the eccentricity change the period of the planet and if Earth's orbit had high eccentricity was more elliptical the seasons would?
The eccentricity does not affect the period.
If the eccentricity were big it would affect the seasons,
but how, is a complicated question.
On the other hand, big eccentricity would make the
Solar System dynamics different (complicated).
The orbital period does not depend on eccentricity. This means that a planet with a longer elliptical orbit will have the same orbital period as a planet with a circular orbit. Remember, the eccentricity of an orbit does not affect a Spacecraft object's orbital period or orbital energy. It simply defines the shape of the orbit. The orbital period does not depend on the eccentricity of the orbit. As long as the semi-major axis is the same, then orbits of different eccentricities around the same object will have the same orbital period. Most planets have eccentric orbits, meaning they are oval-shaped rather than perfectly circular. This means that the amount of heat the planet receives from its host star varies depending on where the planet is on its orbital path. Mercury has a more eccentric orbit than any other planet, taking it to 0.467 AU from the Sun at aphelion but only 0.307 AU at perihelion. With a nearly circular orbit, the length of the seasons is about equal, but as the orbit becomes more elliptical, the length of the seasons will start to vary. Over long periods of time, this can trigger profound climate changes. The earth's spin axis is tilted with respect to its orbital plane. This is what causes the seasons. When the Earth's axis points towards the Sun, it is summer for that hemisphere. When the Earth's axis points away, winter can be expected. "When the Earth's orbit is more elliptical, the planet spends more time farther away from the sun, and the Earth gets less sunlight over the course of the year. So Earth periodically goes from a circular orbit to a more elliptical one (high eccentricity). This is due to the gravitational pull of neighboring planets. Because of its orbital eccentricity, Earth varies in distance from the sun. As a result, it receives less solar radiation causing it to cool. These variations affect the distance between Earth and the Sun. Eccentricity is the reason why our seasons are slightly different lengths, with summers in the Northern Hemisphere currently about 4.5 days longer than winters, and springs about three days longer than autumns.
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Yes, changing the eccentricity of a planet's orbit can change its period. Eccentricity is a measure of how elliptical an orbit is, with a perfectly circular orbit having an eccentricity of 0 and a highly elliptical orbit having an eccentricity close to 1. When a planet's orbit is more elliptical, its distance from the Sun varies more throughout the year. This variation in distance can cause the planet's period to change.
For example, Mercury, the planet closest to the Sun, has a highly elliptical orbit with an eccentricity of 0.2056. This means that Mercury's distance from the Sun varies from about 0.31 AU (astronomical units) at perihelion (closest approach to the Sun) to about 0.47 AU at aphelion (farthest point from the Sun). As a result, Mercury's period is also variable, ranging from about 88 days at perihelion to about 99 days at aphelion.
In the case of Earth, its orbit is much closer to circular, with an eccentricity of only 0.0167. This means that the variation in Earth's distance from the Sun is much smaller, and its period is therefore much more constant. Earth's period is about 365.25 days, and it varies by only about 15 hours throughout the year.
If Earth's orbit had a higher eccentricity, the seasons would be more extreme. This is because the amount of sunlight that a particular region receives depends on its distance from the Sun. When Earth is closer to the Sun, it receives more sunlight, and when it is farther from the Sun, it receives less sunlight.
In a highly elliptical orbit, Earth would spend more time at aphelion, when it is farther from the Sun, than it would at perihelion, when it is closer to the Sun. This would mean that the summers would be cooler and the winters would be colder than they are now.
The eccentricity of Earth's orbit changes very slowly over time, so the effects of this change on the seasons are not noticeable on a human timescale. However, over hundreds of thousands of years, changes in Earth's orbit can contribute to ice ages and other climate changes.
The orbital period of a planet is linked to the semi-major axis of its orbit by Kepler's Third Law, which states that the square of the orbital period is proportional to the cube of the semi-major axis. For two planets at the same average distance from the Sun, if one is in circular orbit and the other in elliptical orbit, then the latter will have a larger semi-major axis and therefore a longer orbital period. Seasons are dependent on the planet's axial tilt, but also on the eccentricity of the orbit, so if the two planets above had the same axial tilt, the one in elliptical orbit would have a shorter, hotter summer and a longer, colder winter than the one in circular orbit would have. That was the basis of Brian W. Aldiss's 'Helliconia' trilogy of novels, in which his imaged planet had a high orbital eccentricity but was otherwise like the Earth. The late Dr. Jack Cohen worked out a consequent cycle of biological activity for life on Helliconia, and it made for intriguing reading.
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