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Nocturn888
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Why do planets rotate around the sun? due to the gravitational field of the sun, which is obvious, but why do they not gradually crash into the sun, due to their motion and the loss of energy after a while ?
The loss of kinetic energy in the rotation of the Earth is due to the combined Earth-Moon system. The Earth and Moon will eventually become tidally locked with each other (the Moon already presents a virtually identical face towards the Earth). The Earth's rotation rate gradually slows down and the distance between the Earth and Moon gradually increases (the combined angular momentum has to stay constant). The varying rotation rate is why leap seconds are required.rbj said:check out what "leap seconds" are all about. the need for an occasional leap second, here or there, is due exactly to loss of kinetic energy in the rotation of the earth.
http://tf.nist.gov/pubs/bulletin/leapsecond.htm
there is kinda an odd reason (having to due with geology and the speed of the Earth's crust) for why they haven't added leap seconds in the past few years. but the rotation of the earth, as a whole, is still slowing down very minutely.
http://www.ucolick.org/~sla/leapsecs/dutc.html
pervect said:Slowing down the rotation of Earth isn't going to cause it to crash into the sun, though.
A careful answer would involve figuring out all the effects that might brake the Earth's orbital motion (there are some), plus the effects that would move the Earth into a higher orbit (there are some of those, too).
A non-careful answer would say that these effects are all so small that we can expect the Sun to turn into a red giant first, at which point the question becomes moot.
BobG said:The loss of kinetic energy in the rotation of the Earth is due to the combined Earth-Moon system. The Earth and Moon will eventually become tidally locked with each other (the Moon already presents a virtually identical face towards the Earth). The Earth's rotation rate gradually slows down and the distance between the Earth and Moon gradually increases (the combined angular momentum has to stay constant).
The varying rotation rate is why leap seconds are required.
The reason they haven't added leap seconds is buried deep in the article (it's not very well organized, even though it pulled together some good material). Primarily, it's because it's becoming more important for systems that have to communicate with each other to be using the same time and, unfortunately, leap seconds have to be added in (or subtracted) manually at irregular times.
You'd think it wouldn't be that difficult to add in the leap second at 0000 Universal Time on the designated day, but ... if a computer can't do it automatically, then it must not be a very good thing.
Planets lose energy in several ways, including through radiation, convection, and conduction. Radiation is the transfer of energy through electromagnetic waves, such as heat from the Sun. Convection is the transfer of energy through the movement of fluids, such as hot air rising. Conduction is the transfer of energy through direct contact, such as when a warm object touches a cooler one.
It is important for planets to lose energy because it helps to regulate their temperature and maintain a stable climate. Without energy loss, planets could become too hot or too cold, making it difficult for life to exist.
No, the rate at which planets lose energy can vary depending on several factors, including their size, composition, distance from the Sun, and atmosphere. For example, smaller planets with less atmosphere will lose energy faster than larger planets with thicker atmospheres.
No, a planet cannot run out of energy. Energy is constantly being transferred and transformed within a planet, and new energy is constantly being received from external sources, such as the Sun. However, a planet's energy balance can become unbalanced, leading to significant changes in its climate and environment.
The loss of energy can affect a planet's orbit in several ways. If a planet loses a significant amount of energy, it can cause its orbit to decay, meaning it will move closer to its parent star. This can also change the planet's rotational speed and may even lead to a change in its axial tilt. These changes can have significant impacts on a planet's climate and habitability.