Difficulties in Viewing Mercury

Since the orbit of Mercury is very close to the Sun, it is difficult to view. The maximum angles from the sun are 18° and 28° at the extremes of its orbit, and the sun moves about 15° per hour. As a result, there is never more than two hours of dark viewing for Mercury. The difficulties are compounded by the eccentricity of the orbit and its inclination to the ecliptic plane (7°, larger than any other except Pluto). With a synodic period of 115.9 days, it is at its maximum extension about six times per year, of which two usually offer good viewing.


Solar System Illustration

Solar System Concepts

Kaufmann, Universe, 3rd Ed
Ch. 10
HyperPhysics********** Astrophysics R Nave
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