Tidal Strengths In terms of the key ratio fg which planetary

Tidal Strengths. In terms of the key ratio f/g, which planetary object is subject to the greatest tidal force, as a fraction of its own gravity: Mercury due to the Sun, the Moon due to Earth, or Io due to Jupiter?

Solution

\"The alignment of the five naked-eye planets just doesn\'t make a difference. The tidal forces we feel from all those planets put together are thousands of times less than lunar and solar tides. In fact, these forces will be even lower than usual this week because all of the planets are about as far away from us as they can get -- on the other side of the Sun.\"

Tides on our planet are caused by the gravitational pull of the Moon and Sun. Earth\'s oceans \"bulge out\" because the Moon\'s gravity pulls a little harder on one side of our planet (the side closer to the Moon) than it does on the other. The Sun\'s gravity raises tides, too, but lunar tides are twice as big. When the Sun and the Moon are approximately aligned (as they are when the Moon is New or Full) we experience especially high tides called \"Spring Tides.\" When there is a 90-degree angle between the two, we get lower tides called \"Neap Tides.\"

Ocean tides on Earth can be as high as 12 meters (40 ft) depending on local geography and the alignment of the Moon and Sun. Earth has solid ground tides too, but they amount to less than 20 centimeters (about 8 inches).

After the Sun and the Moon, Venus is the object in our solar system that produces the biggest tides on Earth. This is simply because the Earth comes closer to Venus than any other planet. Even when the two are separated by their minimum distance of 0.3 AU, which happens every year and a half on average, Venus increases the size of our ocean tides by less than 0.005 cm. (Note: An AU, or \"astronomical unit\", is the distance between the Earth and the Sun. 1 AU = 1.5 x 10⁸ km).

Maximum Tidal Forces of the Sun, Moon, and Planets on the Earth

Solar System Object

Tidal Force

Moon

2.1

Sun

1.00

Venus

0.000113

Jupiter

0.0000131

Mars

0.0000023

Mercury

0.0000007

Saturn

0.0000005

Uranus

0.000000001

Neptune

0.000000002

Pluto

0.0000000000001

Tides caused by the biggest planet in our solar system, Jupiter, are 10 times less than the ones we feel from Venus. Once again the reason involves distance. Although Jupiter is 388 times more massive than Venus, its closest approach to Earth is 14 times greater than our planet\'s minimum distance to Venus.