What do the planets Uranus, Neptune and Pluto have in common?
(A) their atmospheres are very cold, (B) they are all “gas giant” planets, (C) they were all unknown to ancient civilizations, (D) they were all discovered using telescopes, (E) Answers A, C, and D. Correct: (E). They are all very cold, because they are far from the sun and don’t receive much light/heat. They are all too faint to see with the unaided eye (well, you might see Uranus on a very dark, clear night if you know exactly where to look) and were not discovered until telescopes were invented (however, astronomers — being creatures of habit — named them after Roman gods to be consistent with the names of the brighter planets that were known to ancient peoples). Incorrect: As for (B), the Jovian planets (Jupiter, Saturn, Uranus and Neptune) are often referred to as “gas giant” planets. A new term, “ice giants”, is becoming more commonly used for Uranus and Neptune because they contain more ice than gas. Moreover, Pluto is not a Jovian planet — it is a tiny world made of rock and
