Question

Aristarchus's critics argued that parallax was not observed and therefore the Earth could not be in motion. In fact, we know now that the stars are very far away and parallax motion is very small. We examine this by estimating the change in angular size of the angular separation between two stars 6.5 light-years away from the Sun. The two stars are 3.6 light-years apart. Calculate the angular separation of the two stars when the Earth is closest to them in its orbit and when it is farthest away, on the opposite point on its orbit. If human vision (without the aid of a telescope) can at best distinguish a difference of about 0.02°, would the change in angular separation be detectable to the naked eye?

The change in angular separation between the stars is Δα = α_closest - α_farthest =  °.

This change is   (Click to select)   much smaller than   nearly equal to   much larger than   the 0.02° that humans can distinguish without the aid of a telescope. Therefore, this change in angular separation   (Click to select)   would   would not   might under ideal conditions   be detectable to the naked eye.

Answer 1