Bassalisk said:Why ellipse? How come? Why not circular motion? If the path is changing, then the speed is changing, if the speed is changing it means acceleration, if u have acceleration u need extra energy, but Earth doesn't get one..
Thanks
Vagn said:When the Earth is closer to the sun it is moving faster, and therefore has more kinetic energy than when it is further away, so the total energy stays the same, as kinetic energy gets transformed into gravitational potential energy and vice versa.
I get it now, thanks!Vagn said:To have a perfectly circular orbit, then your body initially needs to have exactly the right speed, if this speed is more than the speed for circular motion, but is less than the larger body's escape speed, then the smaller body will undergo an elliptical orbit, if it is equal to the escape speed, then the body will move along a parabolic orbit. Finally if it is greater than the escape speed then it will follow a hyperbolic orbit. Both para and hyperbolic orbits would cause the smaller body to leave the system.
To have exactly the right speed for either parabolic or circular orbits have a very low probability. i.e. 0 chance of occurring.
Earth's path around the sun follows an ellipse because of the gravitational pull of the sun. According to Kepler's laws of planetary motion, planets orbit around the sun in elliptical paths with the sun at one of the focal points.
We know that Earth's path is an ellipse through observations and mathematical calculations. Astronomers have observed the shape of Earth's orbit over time and have also used mathematical equations to calculate the shape of the orbit based on its speed and distance from the sun.
The gravitational pull of the sun is not uniform, meaning that it is stronger when Earth is closer to the sun and weaker when it is farther away. This causes Earth's orbit to deviate from a perfect circle and take on an elliptical shape.
If Earth's path around the sun was a perfect circle, the distance between Earth and the sun would be the same throughout the year. This would result in more extreme and constant seasons, as the tilt of Earth's axis would have a greater impact on the amount of sunlight received.
Yes, Earth's path around the sun is constantly changing due to various factors such as the gravitational pull of other planets and the sun's own movement. However, these changes are very small and occur over long periods of time, so the orbit remains relatively stable and will continue to follow an elliptical path.