Jun 30 2010

Goce satellite

Published by at 5:08 pm under Astrophysics

Hi Dan,

Traveling and the email does not go through.  Thanks for the BBC article link: http://news.bbc.co.uk/2/hi/science/nature/8767763.stm

Since the earth has a magnetic field and gravitions like to follow magnetic field lines, it makes sense that the gravitational field varies slightly over the surface of the earth.  The article says that gravitational acceleration varies from 9.78 m/s^2 (minimum) at the equator to 9.83 m/s^2 (maximum) at the poles.  Looking at a typical pattern of magnetic field lines of a dipole magnet, one would expect a greater gravitational acceleration at the poles of the earth compared to the equator.

8 responses so far

8 Responses to “Goce satellite”

  1. Danon 30 Jun 2010 at 5:36 pm

    Thanks for the reply,

    Could you take the mapped fluctuations in gravity and overlay gamma radiation data (at ~ 312MeV) to show a correlation between your graviton and the gravitational field?

  2. Kevinon 01 Jul 2010 at 8:19 am

    That sounds like a task within a full time job.
    Before going any further, I should add that the gravitational field at a specific location on the earth would also depend on local densities. The magnetic dipole effect is only one effect.

  3. Danon 01 Jul 2010 at 11:44 am

    My question is: Since it appears that they can quantitatively map gravitational acceleration, could you overlay that data map with similar quantitative map of gamma radiation (at the graviton’s wavelength of ~312MeV)? A correlation between the two would be strong observational evidence supporting your graviton. Areas with more gravitational acceleration should also be emitting more gamma radiation, and this new gravity map could allow regional quantitative comparison. This could possibly be done just by looking at previous work. However, I suspect that gamma radiation has not been similarly mapped. If this is the case the comparison could be done in other less robust ways.

  4. Kevinon 01 Jul 2010 at 7:48 pm

    This is the first I have read about the Goce, so again thanks for sending the link. It doesn’t look like the instrument measures gamma rays, and the Fermi Gamma Ray Space Telescope surely cannot map the gravity of the earth anywhere near the precision that Goce can, – too high a flux of gravitons, and you suspected correctly. I would like to study additional detail on how the Goce instrument works simply because it sounds interesting, – maybe once back from vacation.

  5. Carlon 20 Jul 2010 at 10:00 am

    Do other theories for gravity explain the variance from poles to equator? I wish somebody had plans to map graviton emissions from earth, but it seems like most people wouldn’t have a strong reason like this to do so.

    “the gravitational field at a specific location on the earth would also depend on local densities”, wrote Kevin in a post above. But a map of gamma radiation of the appropriate energy (wavelength? same thing?) should precisely correlate with measured gravity for a given location, correct? In other words if the graviton radiation and gravity were both measured at many locations around the earth’s surface, each pair of measurements should correlate exactly according to your calculations.

    Are there other factors that would affect either of the measurements, or should measured gravity always scale along with graviton density (more gravitons equal more gravity, or is there a limit or confounding factors?)

  6. Danon 20 Jul 2010 at 1:38 pm

    That is exactly what I was wondering. However, I do not believe anyone will map gamma radiation across the globe at or around the graviton as you also suspected. The radiation map would have to be high enough resolution, and be taken by a satellite orbiting above each region to make the composite map. On the other hand, there may be a single gamma ray image of the earth that could give a rough comparison…

  7. Chrison 28 Jul 2010 at 12:11 pm

    Part of the difference in the earth acceleration is explained by it rotation, is it not? If one is standing on the equator one is subject to centripetal force due to earths rotation, and therefore will feel minutely lighter than when standing on the poles where no such effect exists. Quite easy to quantify, if one would be so inclined.

  8. Kevinon 28 Jul 2010 at 6:41 pm

    The GOCE satellite is not on the earth, and the only centrifugal force it feels is mv^2/r, which balances mg when in orbit.

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