Solar Eclipse on Mars (Refer to Exercise 69.) The sun's distance from the surface of Mars is approximately 142,000,000 mi. One of Mars' two moons, Phobos, has a maximum diameter of 17.4 mi. (Data from The World Almanac and Book of Facts.) b. Phobos is approximately 5800 mi from Mars. Is it possible for Phobos to cause a total eclipse on Mars?

Key Concepts

Angular Size

Angular size refers to the apparent size of an object as seen from a specific point, measured in degrees. It is determined by the object's actual size and its distance from the observer. In the context of eclipses, both the sun and the moon's angular sizes must be compared to determine if one can completely cover the other during an eclipse.

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 positioned directly between the sun and the planet, with the moon's angular size being equal to or greater than that of the sun as viewed from the planet's surface. Understanding this geometry is crucial for determining the possibility of an eclipse.

Distance and Scale

Distance and scale are essential in evaluating the potential for an eclipse. The distance from Mars to Phobos and the sun must be considered to calculate the relative sizes and positions of these celestial bodies. This helps in assessing whether Phobos can block the sun's light completely when viewed from Mars, which is necessary for a total eclipse.