Solar System Live Help


Orbit Plotting

The orbits of the planets are not coplanar, and many comets and asteroids have highly inclined orbits. The ecliptic is defined as the plane containing the Earth's orbit. With respect to that plane, the other orbits are inclined and thus, in the course of each revolution the planets rise above and fall below the plane of the ecliptic. The portion of the orbit above the plane of the ecliptic is drawn in blue, the portion below in green. Most planets' orbits are only slightly inclined with regard to the ecliptic; notable exceptions are Mercury, 7 degrees and Pluto, a whopping 17.2.

Orbit Scales

Orbits:

Regardless of whether you're viewing just the inner planets or the entire solar system, you can choose among three different scales for the orbits. The default, “Logarithmic”, shows the orbits in a logarithmic scale which preserves their relative scale while compressing the vast empty space of the outer system. “Real” selects a true linear scale which shows just how empty the solar system is; in Real mode you really can't view the inner and outer system on the same display, although specifying a larger image size will help a little.

“Equal” chooses a presentation you may recall from your elementary school Science Is Good textbook (assuming you're young enough to remember elementary school yet old enough to remember when Science was Good)—all the orbits are shown equally spaced from one another (with a tip of the hat to the eccentricity of the orbits of Mercury, Mars, and Pluto). The Equal view isn't included entirely for nostalgia; it's very useful for viewing the solar system as a whole when, for example, you're interested in events such as conjunctions (appulses) between Venus and Jupiter. In Equal view the orbit of any asteroid you're tracking will always be plotted between the orbits of Mars and Jupiter, regardless of where the actual body orbits in the Solar System.

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by John Walker