Solar Simulator 2

Carsten A. Arnholm, 20. October, 2008

The sun has an orbit!

Most people think the Sun rests at the centre of the solar system, and that the planets orbit it. This is almost correct, but not quite.

The Sun and solar orbit - to scale

In reality, the Sun has an orbit like the planets. Both the Sun and the planets orbit the solar system's centre of mass (often referred to as the Barycentre). If you observe the solar system from far above the ecliptic plane (as in the Ulysses orbit), you may see the Sun wobble around a bit, it does not stand still at the centre of the solar system. What you see is the Sun's orbital movements, it is surprisingly complex.

The wobbling is due to the gravitational effects of the planets. Gravity works both ways: The Sun has a (large) effect on the planets, and the planets have a (relatively small) effect on the Sun. This is actually one of the ways one can detect planets around other stars, because a distant star wobbles in a similar manner if it has planets large enough orbiting it.

Ok, so how does the Sun move?

The complexity of the solar orbit is illustrated in the original Solar Orbit Simulator. As it is shown there, the Sun can wander up to ~2.2 solar radii away from the barycentre. The orbit has interesting periodicities which appear to be in synchronicity with, and maybe even have some effect on solar activity. This remains to be proven, though.

The original simulator used a Heliocentric view where the Sun was stationary and the barycentre moved in the view. It is perhaps more realistic to present things as they are perceived by an observer looking in a fixed direction. That is achieved by using a barycentric coordinate system, where the barycentre is at the centre of the view and the Sun moves around it. This is directly equivalent to the example with an observer far above the ecliptic plane.

The current simulator also introduces some features not seen on the original simulator:


The "Solar Simulator 2" program calculates solar system orbits based on the theory presented in Astronomical Algorithms by Jean Meeus. The planetary position algorithms in the book are implemented in the AA+ library by P.J. Naughter. Based on the planetary position data as well as solar and planetary masses, the solar system centre of mass is computed. Solar Simulator 2 builds on the original Solar Simulator. The Solar flares idea came from Hugo Mildenberger, who also kindly provided a C++ library for reading the H-alpha flares data. Hugos library was used to convert the original GOES files to a simpler format used in the simulator.

Software Download

Installation package OS Architecture For OS distro How to install
solarmotion2-1.0-15-linux-2.6-i386.tar.gz Linux 2.6 32bit i386 Built with Kubuntu 8.04 $ sudo ./solarmotion2.install
solarmotion2_flares.tar.gz Linux 2.6 - Flares files for linux Extract to folder
SolarSimulator2_setup_1.0-15.exe Windows .exe Win32 Win2000,XP,Vista Run setup program (flares files included)