Question

Which of the following is not a general difference between terrestrial planets and jovian planets? (a) Terrestrial planets are much smaller and less massive than jovian planets. (b) Terrestrial planets are made largely of metal and rock while jovian planets also contain abundant hydrogen compounds such as methane, ammonia, and water. (c) Terrestrial planets have oceans of liquid water and jovian planets do not.

Short answer

Option (c) is not a general difference.

Step-by-step solution

Understand the characteristics of terrestrial planets

Terrestrial planets are generally smaller, with solid surfaces composed largely of rock and metal. Examples include Earth, Venus, Mars, and Mercury.

Understand the characteristics of jovian planets

Jovian planets are large, gaseous planets that contain significant amounts of hydrogen and helium. These include Jupiter, Saturn, Uranus, and Neptune.

Evaluate Option (a)

Option (a) states that terrestrial planets are much smaller and less massive than jovian planets. This is a true general difference, as terrestrial planets are typically denser but smaller and less massive than jovian planets.

Evaluate Option (b)

Option (b) claims that terrestrial planets are made largely of metal and rock, while jovian planets contain hydrogen compounds such as methane, ammonia, and water. This is also a true difference, highlighting the compositional disparity between the two types.

Evaluate Option (c)

Option (c) states that terrestrial planets have oceans of liquid water and jovian planets do not. This is not generally true for all terrestrial planets; for instance, Venus and Mercury lack oceans.

Determine the incorrect statement

Since option (c) does not consistently apply to all terrestrial planets, it is not a general difference between terrestrial and jovian planets.

Key concepts

Terrestrial Planets

Terrestrial planets, often referred to as the "rocky planets," are found in the inner part of a solar system. Their defining characteristics can help to distinguish them from other types of planets. Generally, terrestrial planets are:

• Smaller in size compared to other planet types, like the jovian planets.
• Characterized by solid surfaces made predominantly of rock and metals.
• Composed of a thin atmosphere, if any, due to their smaller gravity which is not enough to hold a dense gaseous envelope.

Examples of terrestrial planets in our Solar System include Earth, Venus, Mars, and Mercury. Each has a distinct surface, with features such as mountains, valleys, and, in some cases, traces of water. It's this rocky exterior that primarily sets them apart from their gas giant counterparts.

Jovian Planets

Jovian planets, known as the "gas giants," are located in the outer regions of the solar system, distinguishing them in several key areas:

• They are substantially larger in size and mass compared to terrestrial planets.
• They have thick atmospheres composed mainly of hydrogen and helium, contributing to their vast size.
• These planets lack a true solid surface and often have a core likely composed of metal and rock, surrounded by layers of gas.
• They exhibit complex weather systems and frequently have extensive systems of rings and moons.

Jupiter, Saturn, Uranus, and Neptune are examples of jovian planets in our solar system. Their composition and lack of a solid surface are what significantly differentiate them from terrestrial planets.

Planetary Composition

The composition of planets varies significantly between terrestrial and jovian types, shedding light on their formation and characteristics:

• Terrestrial planets are primarily composed of iron, nickel, and silicate minerals. This metallic and rocky composition is responsible for their high density and solid surfaces.
• Jovian planets, on the other hand, contain high quantities of hydrogen and helium. Alongside these, they harbor icy substances and gases like water, ammonia, and methane.

This stark difference in composition has implications for the planets' atmospheres, surfaces, and potential for life. The light gases found in jovian planets lead to lower density and a more volatile environment, while the dense materials in terrestrial planets allow for stability and potentially habitable conditions.

Liquid Water on Planets

Liquid water is a significant aspect when considering the habitability of planets. However, it's important to note the following:

• Not all terrestrial planets have liquid water. For instance, Earth is unique among the terrestrial planets of our solar system for its vast oceans, whereas Venus and Mercury do not possess liquid surface water.
• Jovian planets do not have liquid water on their surfaces due to their gaseous nature and extreme pressures. However, their moons, like Europa and Enceladus, may harbor subsurface oceans.

The presence of liquid water is often linked to the potential for life, making Earth a standout in its ability to support life as we know it. Understanding where liquid water exists helps guide the search for extraterrestrial life in the universe.