why does mars have such low gravity?

Question

I was wondering why mars' gravity is only 38% of ours...
I thought gravity had something to do with it;s speed of rotation- but it's day is almost the same length as ours...
Please help!

Also when it says that mars has some spots of magnetism left from an old planetary system, what does that mean, and how did that happen?

So confused!!!!

Answer 1

Gravity is caused by one thing - mass. It has nothing to do with the speed of rotation (I wonder where that came from, I've never heard that even as a schoolyard myth).
The more mass in an object, the higher the gravity.
Mars has a lot less mass than the Earth, so its gravity is less.

Mars' core is cold and doesn't spin, so Mars has no natural magnetic field the way the Earth does (our core is hot and spins, that creates the magnetic field around the Earth).

When metallic ores cool, they keep the magnetic field that was around them while they wers still molten.
So even though Mars' core has cooled, some metallic deposits on or under the surface still have the remnants of the magnetic field that used to be on Mars.

Answer 2

The force of gravity is proportional to the mass of the planet, so mars has less than earth. The rotation doesn't matter much and actually REDUCES the effective gravity at the equator a tiny bit.

Answer 3

Confused?
Your question deals with with the gravity of Mars.
What causes gravity to be large or small?
The mass of an object, right?
So Mars has less mass than Earth.
Why is that?
Could it be because the core of Mars has less heavy metals than the core of the Earth has? During the years of planet formation possibly Mars just failed to collect up as much heavy stuff like Iron and Nickle as the Earth did. Maybe that happened because Mars was flung farther out into space than Earth was, or rather the space junk floating closer to the Sun had more heavy metals when it started collecting into a planet size object. The stuff farther away just didn't have the same makeup of heavy metals when Mars started forming.

Answer 4

Gravity is equal to the product of two masses divided by the square of the distance between them. G=(M1*M2)/D^2

The mass of Mars is about 1/3 that of Earth, so it shares a gravitational attraction only about 1/3 as strong with an object (you, for example) of a fixed mass, if the object is located at the surface (D=zero).

The causes of magnetic fields are very complex and somewhat imponderable. The simple answer is "the makeup of Mars's core is different (contains less ferrous metal) than that of Earth.

P.S.: gravity has nothing to do with a planet's rotation. Whoever told you that is a goof-bunny.

Answer 5

The force of gravity is proportional to the mass of the planet, so mars has less than earth. The rotation doesn't matter much and actually REDUCES the effective gravity at the equator a tiny bit.

Answer 6

it has low gravity because it isn't as big as Earth. The speed of rotation has a very small effect at counteracting gravity.

There are some stripes of residual magnetism left and these are similar to the stripes found in the sea floor on Earth. There is speculation that this was due to tectonic processes the same as on Earth, except on Mars these ceased a very long time ago.

Answer 7

In answer to your first question....gravity is a function of mass. Mars is less massive than Earth, so it can only offer 38% as much pull (ie 100 lbs here on Earth would only seem like 38 lbs on Mars).

In the distant past, Mars had a magnetic field like our own, due to the dynamo effect. Because of its small size, its core cooled down relatively quickly, causing the dynamo effect to weaken over time, until only a crustal field remained.

Answer 8

Gravity is determined by mass.
Mars has a lower gravity than earth because it's smaller, (weighs less).

Gravity has little to do with speed of rotaion. That comes from the differential of velocities in the material that formed the object.
(Material closer to the primary is orbiting faster).

A magnetic field is generated by a planets molten metallic core. Mars's core seems to have frozen.
There may be residual magnetism in some rock that formed when the field was in place, but it will be of low strength.

Answer 9

The surface gravity on Mars is about 37% less than the Earth's because it is roughly 37% less mass than Earth. An object's rotational period has nothing to do with the magnitude of its gravitational force.

Answer 10

Gravity is proportional to mass, and inversely proportional to the square of the radius (from the center) of the planet. The radius of Mars is 3397 km, which is .5326 earth's. 1/ (.5326 ^ 2) = 3.525, which would be Mars's gravity if it had the same mass as the earth. But Mars has a mass of .1074 earth's, which gives it a gravity of .38 (3.525 x .1074).