# Does the orbital variation in planetary gravity affect the Sun's corona

Dimitris (see below) argues that the syzygies of the Earth and Venus and those of Mercury, Earth and Jupiter distort the Sun's corona, which in some way affects climate on the scale of hundreds of years. Is there any evidence to support the idea that the planets do have such an effect on the sun, other than the correlation noted by Dimitris?

Planetary orbits’ effect to the Northern Hemisphere climate, from solar corona formation to the Earth climate.

Poulos Dimitris

Abstract The four planets that influence the most the solar surface through tidal forcing seem to affect the Earth climate. A simple two cosine model with periods 251 years, of the seasonality of the Earth – Venus syzygies, and 265.4 years, of the combined syzygies of Jupiter and Mercury with Earth when Earth is in synod with Venus, fits well the Northern Hemisphere temperatures of the last 1000 years as reconstructed by Jones et al (1998). Later reconstructions that give too much emphasis on multy-centenial variation are due to increased error. The physical mechanism proposed is that planetary gravitational forces derange the Solar Corona that in turn deranges the planetary geomagnetic field causing temperature variations.

http://www.itia.ntua.gr/getfile/1486/1/documents/PoulosPaper.pdf

• Comments are not for extended discussion; this conversation has been moved to chat. – called2voyage Apr 29 '16 at 14:01

The gravitational effect of the planets on the Sun can be calculated very accurately. The acceleration of a planet of mass $M$ at a distance from the Sun of $r$ is $$a = \frac{G M}{r^2}.$$ If you plug in the numbers, you'll find that the largest effect comes from Jupiter due to its enormous mass. The gravitational acceleration of Jupiter on the Sun is $2\times10^{-7}$ m/s$^2$. Even if all planets were aligned so to add up all their gravitational accelerations, the total would only be $2.8\times10^{-7}$ m/s$^2$.
However, the acceleration is not what is important; rather it is the tidal forces, which are proportional to $1/r^3$ instead on $1/r^2$. The tidal acceleration felt over a distance $\Delta r$ at the surface of the Sun is $$a_{\mathrm{tidal}} \simeq \frac{2GM}{r^3} \Delta r.$$ Now I didn't really bother to read the paper in detail, but the guy doesn't seem to write what exactly in the Sun's atmosphere should be affected by the planets. But even if we say that it's all of Sun's corona, which has a thickness of $\Delta r \sim 10^6$ km, the combined effect of all eight planets standing on a line would be roughly $\mathbf{10^{-9}}$ m/s$\mathbf{^2}$, a minor effect compared to the difference in the Sun's own gravitational field over the same distance, which is 11 orders of magnitude higher.