By how much does the distance between the earth and sun change?

As the planets orbit the sun by how much does this change our distance from the sun due to gravitational effects of the other planets, and has anyone worked out the closest we can get and the furthest we can get as our orbit is warped by the other planets.

6 Answers

  • 1 decade ago
    Best Answer

    The change in the mean distance (from year to year) follows a cycle that is roughly 100,000 years long. The main culprit is Jupiter, with the rest of the planets having much smaller effects.

    However, the change is not regular. For the last few years we have been moving away from the Sun, now we are getting closer.

    In 2009, our mean orbital distance is diminishing. We are talking of small values here (1.000016 au to 0.999998 au from January to June 2009, a difference of 2,700 km ( 1/5 of Earth's diameter ).

    This is completely separate from the eccentricity of the orbit, which takes us (in 2009) from a perihelion of 147,095,260 km to an aphelion of 152,091,221 km. The eccentricity itself changes, following a (roughly) 400,000 year cycle. However, eccentricity -- or even a changing eccentricity -- does not, by itself, change the mean distance. It only changes the distances of perihelion and aphelion.

    There is also another expected effect (but not really measurable): as the Sun produces energy, it loses mass. Four million tonnes per second. As it loses mass, our orbit should move outward. But that is not much (a few metres per million years?).

    Because Earth and Sun orbit a common barycentre, they form a quadropole. As such, they should emit gravitational waves (according to Relativity). This energy being lost to the system should cause the Earth to get closer to the Sun. However, the rate of "gravitational luminosity" is around 300 watts. This effect would not be measurable, even over billions of years.

  • Nick J
    Lv 4
    1 decade ago

    The orbits in the solar system are actually chaotic, although the chaos develops over a period of millions of years. In the shorter term, it all looks nice and orderly - neat, predictable orbits.

    Don't expect any sudden changes from these statistics about the Earth's orbit around the sun:

    aphelion (furthest distance in about July each year)

    152,097,701 km ,1.0167103335 AU

    perihelion (closest approach in about February each year) 147,098,074 km , 0.9832898912 AU

    The other planets have an influence such as gradually changing the angle of the earth's rotational axis over a period of about 28000 years, or the angle of the major axis in the orbit.

    Any gravitational system with more than 2 bodies is chaotic, and the solar system certainly qualifies. However, this is no cause for alarm - there's no evidence of any sudden, fast changes coming along.

  • 1 decade ago

    The Earth's mean distance from the Sun doesn't change. The eccentricity of the Earth's orbit is currently 0.017 meaning that the distance from the Earth to the Sun varies between 147.1 and 152.1 million km (91.4 to 94.6 million miles) over the course of a year. The gravitational effect of the other planets means that this eccentricity alters periodically over thousands of years and can reach a maximum of 0.058, so that the Earth - Sun distance can vary over a year by as much as 141 to 158 million km (88 to 98 million miles).

    The major planets have long been settled into stable orbits which means that they all stay well away from one another.

  • 1 decade ago

    the gravitational interactions between planets makes up almost a negligible change in distance from sun.

    but earth (and all planets) has an elliptical orbit.

    i think earth in particular has a perihelion of about 0.982 AU and and ahopelion of about 1.018 AU (not completely certain, doing this from emmory). In reality that translates into million s of miles/kilometers, etc... but it negligible on the overall scale of things.

    perihelion date for earth is usually on or around January 3.

    aphelion is usually on or around July 4.

    if you live in the northern hemisphere, this would seem odd to you, as we are closer to the sun during our winter... but that's where the tilt of earth's axis comes into play.


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  • Retsum
    Lv 6
    1 decade ago

    The perihelion distance (closest approach q) is given by

    q = a(1 - e)

    and the aphelion distance (furthest away Q) is

    Q = a(1 + e)

    where a is the semi-major axis (1.496 x 10^8 km) and e is the eccentricity (0.017).

  • 6 years ago

    31 million mile difference.

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