The terrestrial planets and the giant planets have different compositions because a. the giant planets are much larger. b. the terrestrial planets are closer to the Sun. c. the giant planets are made mostly of solids. d. the terrestrial planets have few moons.

Terrestrial planets include Mercury, Venus, Earth, and Mars. They are characterized by their solid, rocky surfaces and they are much smaller than giant planets. Because they are closer to the Sun, their surfaces are warmer. This proximity to the Sun also prevents them from retaining light gases like hydrogen and helium, leading to their rocky compositions. These planets have few or no moons and lack significant ring systems.

• Small and rocky
• Closer to the Sun
• Warmer surfaces
• Few or no moons
• Minimal rings

The Earth's atmosphere is a notable exception among terrestrial planets, primarily composed of nitrogen and oxygen. The other terrestrial planets have thinner atmospheres. Mars, for example, has an atmosphere dominated by carbon dioxide.

It's important to remember that terrestrial planets formed from materials that could condense at higher temperatures. This is why they are dense and mainly composed of metals and silicate rocks.

Giant planets, also known as Jovian planets, include Jupiter, Saturn, Uranus, and Neptune. They are significantly larger than terrestrial planets and mainly composed of gases and ices. Unlike terrestrial planets, these planets are located further from the Sun.

• Massive and largely gaseous
• Further from the Sun
• Cooler temperatures
• Many moons
• Prominent ring systems

Their large size helps them retain light gases like hydrogen and helium. Jupiter and Saturn are known for their massive hydrogen-helium atmospheres, while Uranus and Neptune contain higher proportions of water, ammonia, and methane ices. This is why these planets are sometimes referred to as 'ice giants.'

Another unique feature of giant planets is their strong magnetic fields, which are much more powerful than those of terrestrial planets. Their numerous moons and complex ring systems add to their fascinating characteristics.

The process of planetary formation explains why terrestrial and giant planets have different compositions. This process began about 4.6 billion years ago from a rotating disk of gas and dust around the young Sun. As this material began to cool, it condensed into solid grains.

• Formation started from a rotating gas and dust disk
• Temperature influenced material condensation
• Protoplanetary disk material accreted into planetesimals

Close to the Sun, where temperatures were higher, only metals and silicate minerals could condense, forming the terrestrial planets. These materials coalesced into planetesimals and eventually into full-fledged planets.

Further from the Sun, cooler temperatures allowed ices and gases to condense as well as rocks and metals. These ices and gases formed the cores of giant planets. Due to their massive sizes, they had strong gravitational forces capable of attracting and holding onto thick layers of hydrogen and helium from the surrounding nebula.

By understanding planetary formation, we can see how the position relative to the Sun played a crucial role in determining a planet's composition. It's a fascinating process that bridges the realms of chemistry, physics, and astronomy.