Final answer:
The inner planets have thin atmospheres due to their smaller size, weaker gravity, and higher temperatures.
Step-by-step explanation:
The inner planets of our solar system, which include Mercury, Venus, Earth, and Mars, have atmospheres that are significantly different from the outer planets. Unlike the outer planets, the inner planets have very thin atmospheres. The reason for this is that the inner planets are smaller and have weaker gravity compared to the outer planets. This weak gravity is unable to hold on to the gases tightly, causing them to escape into space. Additionally, the inner planets are closer to the Sun and have higher temperatures, which also contribute to the thinness of their atmospheres.