During the eighteenth and nineteenth centuries, attempts to precisely measure theastronomical unit relied largely on rare:
A)total solar eclipses.
B)transits of the inferior planets across the Sun.
C)passages of comets close to the Earth.
D)maximum elongations of Venus.
E)oppositions of Mars.

Question

Quizplus · Accepted Answer

Transits of the inferior planets, specifically Venus, across the face of the Sun provided opportunities for precise measurements of the astronomical unit. These events allowed for triangulation of the distance between the Earth and the Sun based on observations made from different locations on Earth. The method of using transits of the inferior planets across the Sun, such as Venus or Mercury, was first proposed in the eighteenth century and was used to make several attempts to measure the astronomical unit during the following century. These events are rare and occur only in pairs, separated by 8 years, once every 121.5 years. By precisely measuring the timing of these transits from different locations on Earth, astronomers were able to calculate the distance from Earth to the Sun.

During the Eighteenth and Nineteenth Centuries, Attempts to Precisely Measure