This graphic shows orbits of the “Ahead” (red) and “Behind” (blue) observatories relative to the Earth’s orbit (green). “Ahead’s” elliptical orbit fits inside Earth’s orbit and transits around the sun faster than Earth; “Behind’s” is larger than Earth’s orbit and transits around the sun more slowly. Right graphic shows drifting of the observatories (at a rate of 22 degrees per year) away from Earth relative to an Earth-sun reference line (yellow). The “scalloped” lines are caused by the spacecraft’s elliptical orbits.
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