In the late 1800s, Kelvin and Helmholtz suggested that the Sun stayed hot due to gravitational contraction. What was the major drawback to this idea?
A) It predicted that the Sun could shine for about 25 million years, but geologists had already found that Earth is much older than this.
B) It predicted that the Sun would shrink noticeably as we watched it, but the Sun appears to be stable in size.
C) It is physically impossible to generate heat simply by making a star shrink in size.
D) It predicted that Earth would also shrink in size with time, which would make it impossible to have stable geology on our planet.

Question

Quizplus · Accepted Answer

The major drawback to Kelvin and Helmholtz's suggestion was that it predicted the Sun could only shine for about 25 million years, but geologists had already found that Earth is much older than this. This discrepancy between the age of the Sun and the age of Earth was a major problem for the idea of gravitational contraction as the source of the Sun's heat.

In the Late 1800s, Kelvin and Helmholtz Suggested That the Sun