earth appears to be mostly blue when viewed from space because it is mostly covered by ?
a) water
b) oxygen
c) carbon dioxide
d) ozone
water
The correct answer is a) water.
To determine the answer, you can start by understanding that Earth is known as the "Blue Planet" because approximately 71% of its surface is covered by water. When viewed from space, the vast bodies of water, such as the oceans, seas, and lakes, give Earth a predominantly blue appearance. This is due to the way water interacts with sunlight. Sunlight contains all colors of visible light, but when it strikes water, it is primarily absorbed by the water molecules. The absorbed light energy then gets scattered in all directions, with the shorter (blue) wavelengths being scattered more than the longer (red) wavelengths, causing the reflection of blue light. Hence, Earth appears predominantly blue when observed from space.