How does the gravity of the sun affect the shape of the moons orbit around the earth?
- 1 decade agoFavorite Answer
Now, the variation of solar acceleration in course of a lunar orbit is small, but not at all negligible. In fact this small variation is responsible for deviations from an ideal Kepler ellipses. And this deviation causes that the perigee (point of shortest distance between earth and moon) moves around earth in 5.86 years. The difference further causes a retrograde movement of the lunar nodes with a period of 18.61 years.
As the point of sunrise moves north and south in course of a year, the point of moonrise moves north and south in course of a month. The distance between the extreme points varies with the mentioned periodicty. This periodicity played an important role in ancient mythology. Stonehenge for example has this periodicity built in.
And last not least the movement of lunar nodes leads to an 18 yeax, 11.3 days periodicity of solar eclipses which was well known in ancient times..
I would not say that the influence of the sun on the lunar orbit is negligible.
Although not part of the answer, just as a piece of cake: the gravitational force of sun on moon is more than twice as big as the gravitational force of earth on moon. That is why moon primarily orbits sun and not earth.
- freethinkerLv 41 decade ago
The whole of the universe is held together by gravity. Moons orbit planets, planets orbit suns, suns orbit galaxies.
In addition to the Earth's gravity the Sun is also exerting a gravitational force on the Moon as well. The Sun's gravity sometimes causes the Moon to speed up or slow down slightly in its orbit so the Moon's orbital path is constantly being slightly altered by the Sun's gravity. The magnitude of these variations obviously depend on the relative position of the Earth, Sun and Moon.
- blondnirvanaLv 51 decade ago
since the sun is the major attractor in our solar system one should expect that there is an effect on the moon too.
In fact it is slowing the moon down a little while it is travelling away from the sun, and accelerated a little on the other side.
This movement has very little effect on the orbit itself since both inputs are somewhat equal, but over the millions, if not billions of years i could imagine the sun pulling the moons path into the suns equatorial plane.
- MooseBoysLv 61 decade ago
The distance between the earth and the moon (385km) is so much smaller than between the earth and the sun (150 million km), that the difference in acceleration between the moon being between the earth and sun, and the earth being between the sun and moon, is negligible.
Other effects such as tidal forces are much more dominant.Source(s): http://en.wikipedia.org/wiki/Moon
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- ethelineLv 44 years ago
it would not inevitably make the earth orbit the sunlight in yet in a different way however the earth an the moon are spinning at a different course for this reason making the earth spin on its axis extra slowly as a results of gravitational pull of one yet another.