Earth and Moon Rotation
Earth and Moon Rotation
Below is a simulation of the Earth rotating around the Sun and the Moon rotating around the Eath and Sun in a 2D plane. There is an adjustable speed for the rotation of the Earth and Moon in order for you to see how quickly the Earth rotates each day for a year, and how many times the Moon rotates around the Earth also during an Earth year. You might notice that the Sun looks relatively small compared to the Earth and Moon. This is intentional to represent the distance of the Sun relative to the Earth. Along with the simulation, you can choose to see the radius, day and year vectors of the rotating planet we live on.
One thing you might notice is that the Earth takes a relatively long time to make one revolution around the Sun, whereas the Moon makes around 13 revolutions around the Earth for a single Earth revolution around the Sun. This is because of Newton's Law for Universal Gravitation.
The distance between the Sun and the Earth is significantly larger than the distance between the Earth and Moon. The Sun is also significantly more massive than the Earth and the Earth is more massive than the Moon. It is because of these factors that the Moon rotates around the Earth faster than the Earth around the Sun because the Moon is less massive than the more massive Earth but has a smaller distance. This means that there is a larger attraction between the Earth and Moon, prompting the Moon's numerous revolutions about the Earth. The Sun is significantly more massive than the Earth, but their distance is also large. It is mainly because of the distance that it takes a longer amount of time for the Earth to complete one revolution around the Sun.
You can also notice through the vectors that there is a form of centripetal acceleration that the planets experience as the Earth rotates about the Sun, and the Moon about the Earth. In the simulation, the path of the Earth around the Sun and the Moon around the Earth is circular. Realistically the planets in our Solar System follow an elliptical path, but the elliptical path is so small, that if inputted into the simulation, it would still look like a uniform circle. Hence it is worth noting that planets move in an ellipse that is almost circular. Due to this almost circular orbital motion, it can be understood that planets experience centripetal motion as the center of our galaxy, the Milky Way is the Sun, and as that is our planetary point of origin, it makes sense that the planets follow centripetal motion, as they are moving in an elliptical path with constant speed.
In the Solar System simulation, you will be able to see how distance, and planet size plays a role in the Gravitational Force of planets, and how the Centripetal Force acts on planets as the Sun is the center of our planetary system.
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