Final answer:
The gas giants have more mass than terrestrial planets, with Jupiter alone being 318 times more massive than Earth. They also have deep atmospheres due to their strong gravity, as opposed to the thinner atmospheres or lack thereof on smaller, rocky planets.
Step-by-step explanation:
Compared to the terrestrial planets, the gas giants have more mass. The giant planets like Jupiter and Saturn have dense cores roughly 10 times the mass of Earth, surrounded by thick layers of hydrogen and helium. In contrast, terrestrial planets such as Mercury, Venus, Earth, and Mars consist mostly of rocks and metals and have considerably less mass than gas giants.
The massive atmospheres of gas giants are due to their large gravitational fields which can retain light gases like hydrogen and helium. Consequently, these planets have deep atmospheres and opaque clouds, whereas most terrestrial planets have thinner atmospheres due to their lesser gravity and mass. For instance, the Moon, which has about one-sixth of Earth's surface gravity, cannot retain a significant atmosphere over geological timeframes.
Jupiter, the largest gas giant, is 318 times more massive than Earth and possesses a strong magnetic field and significant internal heat, unlike terrestrial planets which are much smaller and mostly lack such characteristics.