10 most difficult planets riddles A list of ten (out of 28) planets related questions that are the most often answered incorrectly Planets quiz Which of Saturn's natural satellites has such distinctive equatorial ridge?Iapetus. The ridge is 13 km high, 20 km wide and 1300 km long. Its origin is not known, but considering the amounts of craters it's safe to assume that this is a very old geological creation.very hard 24% DioneDione12%RheaRhea29%EnceladusEnceladus34%IapetusIapetus24%Created by: Ninjai. Statistics based on 2428 answers in 3 languages »Solar System riddles » How long is stellar year on Mars?687 Earth days. The Martian year is almost twice longer than Earth's year.very hard 28% 687 Earth days687 Earth days28%423 Earth days423 Earth days15%183 Earth days183 Earth days17%121 Earth days121 Earth days37%Created by: Tschuka. Statistics based on 1967 answers in 3 languages »Mars riddles » Which two planets are the closest in size?Uranus and Neptune. The diameters of Uranus and Neptune are respectively 25 362 km and 24 622 km - the difference is only 2.92%.very hard 28% Mercury and MarsMercury and Mars16%Venus and EarthVenus and Earth43%Jupiter and SaturnJupiter and Saturn11%Uranus and NeptuneUranus and Neptune28%Created by: Tschuka. Statistics based on 940 answers in 3 languages »space riddles » Most of the planets of the solar system were known in antiquity. Which was the first discovered in modern times with a telescope?Uranus. Like the classical planets, Uranus is visible to the naked eye, but it was never recognised as a planet by ancient observers because of its dimness and slow orbit. Sir William Herschel announced its discovery on 13 March 1781, expanding the known boundaries of the Solar System for the first time in history and making Uranus the first planet discovered with a telescope. very hard 29% NeptuneNeptune16%UranusUranus29%Jupiter and SaturnJupiter and Saturn32%PlutoPluto20%Created by: Tschuka. Statistics based on 3207 answers in 2 languages »technology riddles » The largest impact crater of the Solar System is:Caloris Planitia is a plain within a large impact basin on Mercury, informally named Caloris, about 1,550 km in diameter. It is one of the largest impact basins in the Solar System. The crater, discovered in 1974, is surrounded by a ring of mountains approximately 2 km (1.2 mi) tall. very hard 29% Valles MarinerisValles Marineris31%CalorisCaloris29%Rupos AltaiRupos Altai21%AristarchusAristarchus17%Created by: Tschuka. Statistics based on 1548 answers in 2 languages »astronomy riddles » Where are the craters of Dostoyevsky, Chopin and Van Gogh?On Mercury. Discovered craters on Mercury are named after outstanding artists. In addition to the above, there are also craters on the Mercury map named after: A. Mickiewicz, L. van Beethoven, F. Goya and C. Monet.very hard 30% On MercuryOn Mercury30%On MarsOn Mars37%On UranusOn Uranus8%There are no such cratersThere are no such craters24%Created by: Tschuka. Statistics based on 3543 answers in 2 languages »astronomy riddles » Which planet of the Solar System is the coldest?Uranus is the seventh planet from the Sun. It has the coldest planetary atmosphere in the Solar System, with a minimum temperature of 49 K (−224 °C; −371 °F).very hard 33% JupiterJupiter4%SaturnSaturn4%UranusUranus33%NeptuneNeptune58%Created by: Tschuka. Statistics based on 4919 answers in 3 languages »astronomy riddles » What is the largest object in Kuiper's belt?Pluto. The chilly expanse of Kuiper Belt holds trillions of objects, remnants of the early Solar System. Pluto, no longer considered a planet, can now be claimed a king of the Kuiper belt, the region of thousands of icy worlds that orbit the sun beyond Neptune. very hard 35% ErisEris19%PlutoPluto35%CeresCeres36%HaumeaHaumea9%Created by: Tschuka. Statistics based on 1140 answers in 2 languages »astronomy riddles » The axis of rotation of this planet is tilted sideways, nearly into the plane of its solar orbit. Uranus. Sometimes the Earth is close to the extension of its axis of rotation. Then it is possible to observe Uranus' moons revolve around the planet.very hard 35% UranusUranus35%MarsMars20%MercuryMercury18%JupiterJupiter25%Created by: Tschuka. Statistics based on 7991 answers in 3 languages »technology riddles » What is the largest moon of Uranus?Titania is the largest of the moons of Uranus and the eighth largest moon in the Solar System at a diameter of 1,578 kilometres. Discovered by William Herschel in 1787, Titania is named after the queen of the fairies in Shakespeare's A Midsummer Night's Dream. Its orbit lies inside Uranus's magnetosphere.very hard 36% OberonOberon16%UmbrielUmbriel17%ArielAriel28%TitaniaTitania36%Created by: Ninjai. Statistics based on 4085 answers in 3 languages »astronomy riddles » Play planets quiz and see all the questions.