Which word or phrase describes the outer planets
The correct answer and explanation is:
Correct Answer: Gas giants
The term “gas giants” is used to describe the outer planets of our solar system, specifically Jupiter, Saturn, Uranus, and Neptune. These planets are significantly different from the inner, terrestrial planets (Mercury, Venus, Earth, and Mars) in terms of composition, size, atmosphere, and overall structure.
Jupiter and Saturn are considered true gas giants because they are composed mostly of hydrogen and helium—the same elements that make up stars. They have very thick atmospheres, deep clouds, and no well-defined solid surface. Their massive sizes and strong gravitational pulls allow them to retain these light gases, which would escape from smaller planets.
Uranus and Neptune are often grouped with Jupiter and Saturn as outer planets, but they are sometimes specifically referred to as ice giants due to their higher concentrations of “ices”—compounds like water, methane, and ammonia. While they still have thick gaseous atmospheres, their interiors are composed of icy and rocky materials rather than being dominated by hydrogen and helium like Jupiter and Saturn.
The term “gas giants” is often used collectively for all four outer planets due to their shared characteristics: large sizes, low densities compared to terrestrial planets, multiple moons, ring systems, and long orbital periods. They are also located far beyond the asteroid belt, which separates the inner and outer planets.
Understanding gas giants is important for studying the formation and evolution of planetary systems. Scientists believe that the outer planets played a crucial role in shaping the solar system by influencing the orbits of other objects and possibly protecting Earth from excessive asteroid impacts. Additionally, many exoplanets discovered in other star systems are gas giants, making them key targets in the search for understanding planets beyond our own solar system.