Solar Eclipse on Neptune (Refer to Exercise 69.) The sun's distance from Neptune is approximately 2,800,000,000 mi (2.8 billion mi). The largest moon of Neptune is Triton, with a diameter of approximately 1680 mi. (Data from The World Almanac and Book of Facts.) b. Triton is approximately 220,000 mi from Neptune. Is it possible for Triton to cause a total eclipse on Neptune?

Key Concepts

Angular Size

Angular size refers to how large an object appears to an observer from a given distance. It is determined by the object's actual size and its distance from the observer. In the context of eclipses, the angular size of the moon (Triton) relative to the sun is crucial in determining whether it can completely cover the sun when viewed from Neptune.

Eclipse Geometry

Eclipse geometry involves the spatial arrangement of the sun, moon, and planet during an eclipse. For a total eclipse to occur, the moon must be directly between the sun and the planet, with the moon's angular size being equal to or greater than that of the sun as seen from the planet. Understanding this geometry helps in assessing the conditions under which Triton could cause a total eclipse on Neptune.

Distance and Scale

Distance and scale are fundamental in understanding celestial events. The vast distances between celestial bodies, such as the sun, Neptune, and Triton, affect their apparent sizes and the likelihood of eclipses. In this scenario, calculating the distances involved helps determine if Triton is sufficiently large and close enough to Neptune to block the sun's light entirely.