Final answer:
Uranus and Neptune are categorized as ice giants and are the farthest planets from the sun in our solar system, located beyond Saturn where the temperatures significantly decrease.
Step-by-step explanation:
The planets Uranus and Neptune are known as ice giants due to their unique composition which is different from the gas giant planets, Jupiter and Saturn. These two ice giants have a higher density, and astronomers have found that exoplanets similar in size to Uranus and Neptune are quite common, which points to a fundamental difference in composition from the larger gas giants like Jupiter and Saturn.
Uranus and Neptune are located in the outer reaches of our solar system, with Uranus lying at approximately 19 AU (Astronomical Units) from the sun and Neptune at about 30 AU. They both have long orbital periods around the sun due to their vast distances, making seasonal changes difficult to study. Unlike Jupiter and Saturn, Uranus does not emit a measurable amount of internal heat while Neptune does have a small internal energy source, yet they share roughly the same atmospheric temperature, even with Neptune being farther from the Sun.
Regarding the sentence completion question, the correct phrasing would be: The planets Uranus and Neptune are known as the ice giants. These planets are the farthest away from the sun in the solar system. They lie just beyond the planet Saturn, at which point temperatures drastically decrease.