Question

with the use of the hubble space telescope, scientists recently discovered a runaway star. it is 90 times larger than the sun and is very hot and blue-white in color. why does the sun appear to be brighter than this runaway star when viewed from earth?
a the sun is a different color than the runaway star.
b the sun is older than the runaway star.
c the sun is closer to earth than the runaway star.
d the sun is made of different elements than the runaway star.

Explanation:

The brightness of a star as seen from Earth depends on its actual luminosity and its distance from Earth. Even if the runaway star is larger and hotter (which might imply higher luminosity), if it is much farther away from Earth than the Sun, the Sun will appear brighter. Options A (color), B (age), and D (elements) do not directly affect the apparent brightness in the way the question is asking. Distance (Option C) is the key factor here as per the inverse - square law of light (apparent brightness \(B=\frac{L}{4\pi d^{2}}\), where \(L\) is luminosity and \(d\) is distance).

Answer:

C. The sun is closer to Earth than the runaway star.