Viewed from Earth,the Sun's absolute magnitude is M = 4.8 and its apparent magnitude is m = -26.7.Viewed from Neptune,30 AU from the Sun,the Sun's apparent magnitude is:
A) 4.8.
B) 12.8.
C) -19.3.
D) -26.7.

Question

Quizplus · Accepted Answer

The apparent magnitude of a star changes with distance. The formula relating apparent magnitude (m), absolute magnitude (M), and distance (d in parsecs) is m = M + 5(log10(d) - 1). Neptune is 30 AU from the Sun, which is approximately 30/206265 parsecs. Using this formula, the apparent magnitude of the Sun from Neptune is approximately -19.3.

Viewed from Earth,the Sun's Absolute Magnitude Is M = 4