Is the earth heavier now than it was 1000 years ago? Has the gravity of the earth increased?

Question

Apparently this was a topic of discussion on the radio. My husband asked me this, and I honestly don't know. He says that logically, because there are more people on earth, and because the earth has been struck by meteorites that the earth should be heavier; if so the additional mass would increase the gravity of the earth.

Answer 1

Logically, thats only half right -- meteorites add mass, extreme heating of gases loses mass -- as long as we have a cool enough atmosphere, the former can dominate.

Unless people are striking the earth from outer space, the number of humans has no impact on the overall mass. :)

Answer 2

The atmosphere is lost to space due to solar wind on a continuous basis. The elements that make up the atmosphere *ultimately* come from volcanoes. I wouldn't venture to guess whether or not this exceeding the influx from meteorites or dust. Also consider that over geological time periods, the earth is cooling (as the isotopes that heat it within decay) and, therefore, shrinking. This increases the surface gravity via the inverse square law.

Answer 3

The number of people makes no difference. People did not magically appear on Earth; they are made of materials that have always been here.

Yes, meteorites are constantly adding mass to the Earth, but the amount is so small that the resulting change in surface gravity is imperceptible.

Answer 4

Very unlikely!
Matter is neither created nor destroyed, it simply changes form. That is a fundamental conservation law of physics. The matter we are made out of comes from the food and water we eat and drink, which in turn come from the earth. (Remember we are 75% water) So to to say that people, plants, and other animals have increased the mass of the earth would not be accurate. Unless you got your food and water from another planet.

In terms of meteorites: No not in any significant fashion. Gravity is a relatively week force (as compared to other forces such as the electromagnetic force). A very large change in mass would be required to have a measurable effect on earths gravitational field.

For the person who said:
"Number of people might have affected cuz mass is in different forms and not at the same point as it was before but again the change is so small"
I believe you are making the argument that "we" may be stealing mass from the earth because we are seperate bodies.
That is not the case at all. When one calculates the graviational potential of a spherically symetric massive body such as the earth according to Newton's universal law of gravity, one would find that gravity acts is if all of the mass is concentrated at the body's center. For example: If you were to drill a hole half way to the center of the earth and climb down it, you would find that at the bottom of your hole the gravitational force is half that at the earths surface. In other words you would weigh half as much.
So even though our "mass is in different forms and not at the same point" gravity would still behave as if all of our mass and mass of the earth was concentrated at its center.
( yes there may be a slight change in earth's mass density but that flucuates day to day depending on how much water is in the atmosphere and such.)

Answer 5

The earth is getting heavier. This is due mostly to solar dust. The earth collects tons and tons of dust a day. Increase of population is not as much as the dust. This will not affect gravity much.

Answer 6

humans dont cuz gravity change cuz matter is conserved, we came from dust and dust was in earth already but i guess since the mass in earth is less concentrated than before, the earth's gravity to attract outter object has changed. Yeah the meteorites ur rite.

Answer 7

The people had to come from earth resources. No addition there. We have been collecting dust and meteors but it's so small compared to the earth's mass, we could never measure it.

Answer 8

The birth of people would have no affect on the weight of the earth but meteorites accumulating on it would.

Answer 9

no - gravity has nothing to do with the # of ppl on earth

Answer 10

i would say that he is right on both points