Question
(ii) The four moons are approximately the same distance from the Earth However, they do not have the same brightness. Suggest one reason for this. __
Answer
4.3
(156 Votes)
Gilbert
Master · Tutor for 5 years
Answer
One reason for the differing brightness of the moons, despite equal distances from Earth, could be variations in their albedo or surface reflectivity, which essentially alters the amount of sunlight that each of them reflects back to Earth.
Explanation
## Step 1: In astronomy, the brightness or apparent magnitude of a celestial object, such as a moon, is a measure of how brightly the object appears to an observer on Earth's surface. ## Step 2: Whilst exact equidistance from the Earth to the moons would posit equal brightness, different factors can significantly affect the exact brightness that these celestial objects portray when viewed from Earth's surface. ## Step 3: One determining factor could be the albedo or reflectivity of an object. While the four moons are roughly at the same distance from the Earth, they are likely to have different surface reflectivity depending on their geological composition (such as the presence of ice or rock), causing disparities in their brightness. **For instance, with strictly equal distances, the higher a moon's albedo, the more sunlight it reflects back to us, appearing brighter. A lower albedo would result in less reflected sunlight, making the moon appear dimmer.**