What does rotational speed of planets depends on?

Question

Hi pets,

How come Earth's rotation around its axis takes almost 24 hours while Venus rotates once every 243 Earth days? Why so large differences between planets?

Cheers!

Answer 1

For any planet, its rotation period about their own axis is different. As pointed out by you, Earth takes 24 hours, venus rotates in 243 earth days so on so forth is completely governed by the physics and dynamics.



The rotational period of a planet essentially depends on the following factors.



!). Evolution of the planet. That is to say, The Initial conditions of the planet, ;including its rotation momentum, moment of inertia etc, when the planet was born either from the surface of sun or any celestail object which came near to the sun and due to gravity stared rotating about sun. We call them as Inititial conditions.



2). The materials(especially liquid) present on the surface of those objects). This is a time dependent phenomenon. this parameter largely affects the self rotation of planet and evolves over a period of time. It may remain constant or change that depends largely on the distribution of non uniform mass or density.



3). moons if any also affect the rotational period due to gravity.



4). the number of asteroids or meteors hitting the planet or Celestial objects.



5). Gravity due to other surrounding objects.





the thing is that the period of self revolution is largely affected by these parameters how ever, it will be very difficult for us to estimate the contribution of these parameters because, it requires complex mathematical analysis and information about the evolution of planets which we do not have.

Answer 2

Venus rotates once every 243 Earth days—by far the slowest rotation period of any of the major planets. At the equator, the Venusian surface rotates at 6.5 km/h; on Earth, the rotation speed at the equator is about 1,670 km/h.

A Venusian sidereal day thus lasts longer than a Venusian year (243 versus 224.7 Earth days).



However, because of the retrograde rotation, the length of a solar day on Venus is significantly shorter than the sidereal day. To an observer on the surface of Venus the time from one sunrise to the next would be 116.75 Earth days (making the Venusian solar day shorter than Mercury's 176 Earth days) Additionally, the Sun would appear to rise in the west and set in the east. As a result of Venus's relatively long solar day, one Venus year is about 1.92 Venus days long.



A curious aspect of the Venusian orbit and rotation periods is that the 584-day average interval between successive close approaches to the Earth is almost exactly equal to five Venusian solar days. Whether this relationship arose by chance or is the result of tidal locking with the Earth, is unknown

Answer 3

there is not any correlation with length and rotation velocity. Venus and Earth are the comparable length yet Earth rotates 243 cases quicker than Venus. Jupiter and Saturn are the biggest planets and that they have got the quickest rotation velocity, so i'm uncertain why you assert, " most of the bigger planets do no longer seem to be turning as speedy as they could".

Answer 4

To be honest nobody really knows, but it depends on the angular moment delivered by the bodies that accreted to make the planet. In some case tidal effects can spin a planet down (ie Mercury).

Answer 5

There isn't a real reason other than that is just how its formed when it formed. Once upon a time there was angular momentum and that angular momentum just must be conserved.





Only Mercury really has a real reason for its rotation rate. It has a tidal resonance with the sun.