If I were on Mars, how often would I see Earth transit the Sun?
STEVEN RISER, CONYERS, GEORGIA
From Mars, Earth transits the Sun four times in a 284-year cycle. The transits occur in either May or November at intervals of 100.5, 79, 25.5, and 79 years. During these events, Earth and the Moon would be seen as small black dots moving across the Sun's disk.