Fun Facts About the Planets

Fun Facts About the Planets: all 157, explained

1. A day on Venus is longer than a year on Venus.

   Venus takes about 243 Earth days to spin once on its axis, but only about 225 Earth days to orbit the Sun. It also spins backwards compared with most planets, so on Venus the Sun would rise in the west.

   Source: Venus (Wikipedia) · Fact card

2. Saturn is less dense than water.

   Saturn is mostly hydrogen and helium, and its average density is lower than that of water. In theory, if you had a bathtub big enough, Saturn would float, although it would not survive the experience.

   Source: Saturn (Wikipedia) · Fact card

3. Mars has a volcano about two and a half times as tall as Mount Everest.

   Olympus Mons on Mars rises about 22 kilometres above the surrounding plains, and its base is roughly the size of the state of Arizona. It is one of the largest volcanoes in the Solar System.

   Source: Olympus Mons (Wikipedia) · Fact card

4. Jupiter’s Great Red Spot is a storm bigger than Earth.

   The Great Red Spot is a giant storm in Jupiter’s atmosphere that has been observed for well over 150 years. It has been shrinking, but it is still wider than our planet.

   Source: Great Red Spot (Wikipedia) · Fact card

5. Uranus spins on its side.

   Uranus is tilted by about 98 degrees, so it rolls around the Sun like a ball. Each pole gets about 42 years of continuous sunlight followed by 42 years of darkness. A giant collision long ago is the leading explanation.

   Source: Uranus (Wikipedia) · Fact card

6. Mars is red because it’s covered in rust.

   The dust and rocks on Mars contain a lot of iron oxide, the same compound as rust. Fine red dust blown into the air gives the sky an orange-pink tint too.

   Source: Mars (Wikipedia) · Fact card

7. Sunsets on Mars are blue.

   Fine Martian dust scatters blue light forward, near the direction of the Sun. As the Sun sets, the sky around it glows blue, the reverse of Earth.

   Source: Mars (Wikipedia) · Fact card

8. Mars has two small, potato-shaped moons named Fear and Dread.

   Phobos and Deimos are named after the sons of Ares, the Greek god of war, and mean fear and dread. Phobos is slowly spiralling closer to Mars and will eventually break apart or crash into it.

   Source: Moons of Mars (Wikipedia) · Fact card

9. A day on Mars is only about 40 minutes longer than a day on Earth.

   One Martian day, called a sol, lasts about 24 hours and 40 minutes. A Martian year, though, is 687 Earth days.

   Source: Mars (Wikipedia) · Fact card

10. Saturn’s rings are huge but in many places only about 10 metres thick.

    The main rings stretch hundreds of thousands of kilometres across but are extremely thin. They are made mostly of chunks of water ice, from tiny grains to pieces the size of a house.

    Source: Rings of Saturn (Wikipedia) · Fact card

11. Saturn has more known moons than any other planet: over 270.

    Astronomers keep finding small moons around Saturn, and its count passed 270 in 2025. The largest, Titan, is bigger than the planet Mercury and has lakes of liquid methane.

    Source: Moons of Saturn (Wikipedia) · Fact card

12. Jupiter spins so fast that a day there lasts less than 10 hours.

    Jupiter is the biggest planet in the solar system, yet it completes one rotation in about 9 hours and 56 minutes, the shortest day of any planet. The fast spin makes it bulge at the equator.

    Source: Jupiter (Wikipedia) · Fact card

13. Jupiter’s moon Ganymede is bigger than the planet Mercury.

    Ganymede is the largest moon in the solar system. It is the only moon known to have its own magnetic field and is thought to hide a salty ocean under its icy crust.

    Source: Ganymede (moon) (Wikipedia) · Fact card

14. Jupiter is more than twice as massive as all the other planets combined.

    Jupiter’s mass is about 318 times that of Earth and roughly two and a half times the mass of all the other planets in the solar system put together.

    Source: Jupiter (Wikipedia) · Fact card

15. Neptune has the fastest winds in the solar system.

    Winds on Neptune have been measured at around 2,000 km/h, faster than the speed of sound on Earth, even though the planet is far from the Sun’s heat.

    Source: Neptune (Wikipedia) · Fact card

16. Neptune was found by maths before anyone saw it.

    Astronomers noticed Uranus was being tugged off course and calculated where an unseen planet must be. In 1846, Johann Galle pointed a telescope at the predicted spot and found Neptune.

    Source: Neptune (Wikipedia) · Fact card

17. Neptune completed its first full orbit since its discovery only in 2011.

    Neptune takes about 165 Earth years to go around the Sun. It was discovered in 1846, so it did not return to the same spot until 2011.

    Source: Neptune (Wikipedia) · Fact card

18. Venus is the hottest planet, even though Mercury is closer to the Sun.

    Venus’s thick carbon dioxide atmosphere traps heat, keeping the surface at around 465 °C, hot enough to melt lead. Mercury has almost no atmosphere, so its heat escapes.

    Source: Venus (Wikipedia) · Fact card

19. After the Moon, Venus is the brightest natural object in the night sky.

    Venus is bright because it is close and covered in reflective clouds. It is often called the morning or evening star because it shines near sunrise or sunset.

    Source: Venus (Wikipedia) · Fact card

20. Mercury and Venus are the only planets with no moons.

    Every other planet in the solar system has at least one moon. Mercury is also the smallest planet and the closest to the Sun.

    Source: Mercury (planet) (Wikipedia) · Fact card

21. On Mercury, temperatures swing from about 430 °C in the day to about minus 180 °C at night.

    Mercury has almost no atmosphere to hold heat, so the sunlit side bakes and the night side freezes. A year on Mercury is only 88 Earth days.

    Source: Mercury (planet) (Wikipedia) · Fact card

22. Uranus was the first planet discovered with a telescope.

    William Herschel spotted Uranus in 1781, at first thinking it was a comet. All the planets closer to the Sun were known since ancient times because they are visible to the naked eye.

    Source: Uranus (Wikipedia) · Fact card

23. Earth isn’t a perfect sphere. It bulges at the equator.

    Earth’s spin flattens it slightly, so the distance through the equator is about 43 km more than from pole to pole. Because of the bulge, the peak of Chimborazo in Ecuador is the point farthest from Earth’s center.

    Source: Earth (Wikipedia) · Fact card

24. Pluto has a giant heart-shaped plain on its surface.

    When NASA’s New Horizons probe flew past Pluto in 2015, it photographed a bright heart-shaped region, now called Tombaugh Regio after Pluto’s discoverer, Clyde Tombaugh.

    Source: Pluto (Wikipedia) · Fact card

25. Pluto was a planet for 76 years.

    Pluto was discovered in 1930 and counted as the ninth planet until 2006, when the International Astronomical Union reclassified it as a dwarf planet after similar objects were found beyond Neptune.

    Source: Pluto (Wikipedia) · Fact card

26. A year on Mars lasts 687 Earth days.

    Mars is farther from the Sun than Earth, so it takes almost twice as long to complete an orbit.

    Source: Mars (Wikipedia) · Fact card

27. Mars has a canyon system that would stretch across the United States.

    Valles Marineris is about 4,000 kilometers long and up to 7 kilometers deep, making the Grand Canyon look small.

    Source: Valles Marineris (Wikipedia) · Fact card

28. The air on Mars is about 100 times thinner than Earth’s.

    The Martian atmosphere is mostly carbon dioxide, and its pressure at the surface is less than 1% of Earth’s, so liquid water would quickly boil or freeze.

    Source: Atmosphere of Mars (Wikipedia) · Fact card

29. You would weigh only about 38% as much on Mars.

    Mars is smaller and less massive than Earth, so its surface gravity is about 0.38 of ours. A 100-pound child would weigh about 38 pounds there.

    Source: Mars (Wikipedia) · Fact card

30. Mars has ice caps at both poles.

    The polar caps are made of water ice with a seasonal layer of frozen carbon dioxide that grows in winter and shrinks in summer.

    Source: Martian polar ice caps (Wikipedia) · Fact card

31. Dust storms on Mars can cover the whole planet.

    Global dust storms can last for weeks or months. One in 2018 blocked so much sunlight that NASA’s solar-powered Opportunity rover lost power and never woke up.

    Source: Opportunity (rover) (Wikipedia) · Fact card

32. A small helicopter made the first powered flight on another planet, on Mars in 2021.

    NASA’s Ingenuity helicopter flew on Mars on 19 April 2021 and went on to make 72 flights, far more than the five originally planned.

    Source: Ingenuity (helicopter) (Wikipedia) · Fact card

33. Mars is the only planet known to be inhabited entirely by robots.

    Rovers, landers and orbiters from several countries have explored Mars since the 1970s, including NASA’s Curiosity and Perseverance rovers and China’s Zhurong.

    Source: Exploration of Mars (Wikipedia) · Fact card

34. Mars is about half as wide as Earth.

    Its diameter is about 6,779 kilometers, roughly 53% of Earth’s, but its land area is about the same as all of Earth’s dry land.

    Source: Mars (Wikipedia) · Fact card

35. Mars is the fourth planet from the Sun.

    It orbits at an average distance of about 228 million kilometers, about one and a half times as far as Earth.

    Source: Mars (Wikipedia) · Fact card

36. Mars is named after the Roman god of war.

    Its blood-red color reminded ancient observers of war. Its moons Phobos and Deimos are named after the sons of the Greek war god Ares.

    Source: Mars in culture (Wikipedia) · Fact card

37. Mars has seasons, like Earth.

    Its axis is tilted about 25 degrees, close to Earth’s 23.4, so it has seasons, but each lasts roughly twice as long.

    Source: Mars (Wikipedia) · Fact card

38. Mars is very cold: around minus 60°C on average.

    Temperatures can reach about 20°C at the equator on a summer afternoon and fall below minus 120°C at the poles.

    Source: Climate of Mars (Wikipedia) · Fact card

39. Mars once had rivers and lakes.

    Dried riverbeds, deltas and minerals that form in water show that liquid water flowed on Mars billions of years ago.

    Source: Water on Mars (Wikipedia) · Fact card

40. The first successful landing on Mars was in 1976.

    NASA’s Viking 1 lander touched down in July 1976 and sent back the first photos from the Martian surface.

    Source: Viking 1 (Wikipedia) · Fact card

41. A NASA rover has been collecting rock samples on Mars to bring back to Earth.

    Perseverance, which landed in Jezero Crater in 2021, seals rock cores in tubes for a future sample-return mission.

    Source: Perseverance (rover) (Wikipedia) · Fact card

42. Pieces of Mars have landed on Earth.

    More than 300 meteorites found on Earth have been identified as Martian, blasted off Mars by asteroid impacts.

    Source: Martian meteorite (Wikipedia) · Fact card

43. Mars comes closest to Earth about every 26 months.

    At these oppositions Mars can come within about 56 million kilometers, which is when space agencies usually launch missions.

    Source: Mars (Wikipedia) · Fact card

44. The daytime sky on Mars is a butterscotch color.

    Fine dust in the air scatters light, giving the Martian sky a pinkish-tan color by day.

    Source: Atmosphere of Mars (Wikipedia) · Fact card

45. Mars has a huge volcanic region called Tharsis.

    Tharsis is home to four giant volcanoes, including Olympus Mons, and is so massive it may have shifted the planet’s tilt.

    Source: Tharsis (Wikipedia) · Fact card

46. You could jump almost three times as high on Mars.

    With gravity only about 38% of Earth’s, the same jump would take you nearly three times higher.

    Source: Gravity of Mars (Wikipedia) · Fact card

47. Sunlight on Mars is less than half as strong as on Earth.

    Because Mars is farther from the Sun, the light reaching it is about 43% as intense, which matters for solar-powered rovers.

    Source: Mars (Wikipedia) · Fact card

48. From Mars, Earth looks like a bright evening or morning star.

    Rovers have photographed Earth as a small bright dot in the Martian sky.

    Source: Earth from Mars (Wikipedia) · Fact card

49. Mars has one of the biggest impact craters in the solar system.

    Hellas Planitia is about 2,300 kilometers across and about 7 kilometers deep.

    Source: Hellas Planitia (Wikipedia) · Fact card

50. Scientists have detected puzzling traces of methane on Mars.

    NASA’s Curiosity rover measured small, changing amounts of methane, a gas that on Earth is often made by living things, though it can also come from geology.

    Source: Atmosphere of Mars (Wikipedia) · Fact card

51. Mars lost its global magnetic field long ago.

    Without a magnetic shield, the solar wind gradually stripped away much of Mars’s atmosphere.

    Source: Mars (Wikipedia) · Fact card

52. Jupiter is the fifth planet from the Sun and the largest.

    It is about 11 times as wide as Earth, and more than 1,300 Earths could fit inside it.

    Source: Jupiter (Wikipedia) · Fact card

53. Jupiter has no solid surface.

    It is a gas giant made mostly of hydrogen and helium, getting denser and hotter toward a possible rocky core.

    Source: Jupiter (Wikipedia) · Fact card

54. Jupiter has around 95 known moons.

    The count keeps rising as telescopes find small, distant moons.

    Source: Moons of Jupiter (Wikipedia) · Fact card

55. Galileo discovered Jupiter’s four biggest moons in 1610.

    Io, Europa, Ganymede and Callisto are called the Galilean moons. Seeing them orbit Jupiter helped show that not everything circles Earth.

    Source: Galilean moons (Wikipedia) · Fact card

56. Jupiter’s moon Io is the most volcanic place in the solar system.

    Tidal squeezing from Jupiter heats Io’s interior, powering hundreds of active volcanoes.

    Source: Io (moon) (Wikipedia) · Fact card

57. Jupiter’s moon Europa probably hides an ocean under its ice.

    Scientists think the ocean holds more water than all of Earth’s oceans, making Europa a target in the search for life.

    Source: Europa (moon) (Wikipedia) · Fact card

58. Jupiter has faint rings.

    They are made of dust and were discovered by the Voyager 1 probe in 1979.

    Source: Rings of Jupiter (Wikipedia) · Fact card

59. A year on Jupiter lasts about 12 Earth years.

    Jupiter orbits the Sun at an average of about 778 million kilometers.

    Source: Jupiter (Wikipedia) · Fact card

60. Jupiter has the strongest magnetic field of any planet.

    It is about 20,000 times stronger than Earth’s and traps intense radiation belts around the planet.

    Source: Magnetosphere of Jupiter (Wikipedia) · Fact card

61. Jupiter has auroras bigger than Earth.

    They glow at the poles in ultraviolet light and are powered partly by material from the moon Io.

    Source: Jupiter (Wikipedia) · Fact card

62. NASA’s Juno spacecraft has orbited Jupiter since 2016.

    Juno studies the planet’s interior, gravity and magnetic field from a polar orbit.

    Source: Juno (spacecraft) (Wikipedia) · Fact card

63. A comet smashed into Jupiter in 1994.

    Fragments of Comet Shoemaker-Levy 9 hit Jupiter over several days, leaving dark scars larger than Earth.

    Source: Comet Shoemaker-Levy 9 (Wikipedia) · Fact card

64. Jupiter’s gravity may protect Earth from some comets.

    Its huge gravity pulls in or flings away many objects, though scientists still debate how much it shields Earth.

    Source: Jupiter (Wikipedia) · Fact card

65. Jupiter is often the fourth-brightest object in the night sky.

    Only the Moon and Venus are usually brighter, and sometimes Mars at close approach.

    Source: Jupiter (Wikipedia) · Fact card

66. Jupiter is named after the king of the Roman gods.

    Many of its moons are named after figures from myths about Jupiter, or Zeus in Greek myth.

    Source: Jupiter (mythology) (Wikipedia) · Fact card

67. Jupiter’s stripes are bands of clouds moving in opposite directions.

    Light zones and dark belts are separated by powerful jet streams.

    Source: Atmosphere of Jupiter (Wikipedia) · Fact card

68. Jupiter’s top clouds are made of ammonia ice.

    Lower layers are thought to contain ammonium hydrosulfide and water clouds.

    Source: Atmosphere of Jupiter (Wikipedia) · Fact card

69. The Great Red Spot is shrinking.

    It was about three Earths wide in the late 1800s and is now a little wider than one Earth.

    Source: Great Red Spot (Wikipedia) · Fact card

70. Ganymede is the only moon known to have its own magnetic field.

    It probably comes from a molten iron core inside the moon.

    Source: Ganymede (moon) (Wikipedia) · Fact card

71. Callisto is one of the most heavily cratered objects in the solar system.

    Its ancient surface has barely changed for billions of years.

    Source: Callisto (moon) (Wikipedia) · Fact card

72. The first spacecraft to fly past Jupiter was Pioneer 10, in 1973.

    It sent back the first close-up images of the planet.

    Source: Pioneer 10 (Wikipedia) · Fact card

73. Jupiter gives off more heat than it receives from the Sun.

    It is still slowly releasing heat left over from its formation.

    Source: Jupiter (Wikipedia) · Fact card

74. Jupiter would need to be about 80 times more massive to become a star.

    That is roughly the minimum mass needed to start hydrogen fusion.

    Source: Jupiter (Wikipedia) · Fact card

75. Thousands of asteroids share Jupiter’s orbit.

    The Trojan asteroids gather in two groups ahead of and behind Jupiter. NASA’s Lucy mission launched in 2021 to visit them.

    Source: Jupiter trojan (Wikipedia) · Fact card

76. A NASA spacecraft is on its way to study Europa.

    Europa Clipper launched in October 2024 and is due to arrive at Jupiter in 2030.

    Source: Europa Clipper (Wikipedia) · Fact card

77. Europe’s JUICE mission is heading to Jupiter’s icy moons.

    The European Space Agency’s probe launched in 2023 and will eventually orbit Ganymede.

    Source: Jupiter Icy Moons Explorer (Wikipedia) · Fact card

78. Saturn is the sixth planet from the Sun and the second largest.

    It is about nine times as wide as Earth.

    Source: Saturn (Wikipedia) · Fact card

79. Saturn’s rings are made mostly of chunks of ice.

    The pieces range from tiny grains to boulders as big as houses.

    Source: Rings of Saturn (Wikipedia) · Fact card

80. Saturn’s main rings would stretch most of the way from Earth to the Moon.

    The main rings extend up to about 280,000 kilometers across.

    Source: Rings of Saturn (Wikipedia) · Fact card

81. Saturn’s rings seem to disappear every 13 to 16 years.

    When Earth passes through the plane of the rings, we see them edge-on and they almost vanish from view. This happened in 2025.

    Source: Rings of Saturn (Wikipedia) · Fact card

82. Galileo thought Saturn had "ears".

    His 1610 telescope could not show the rings clearly. Christiaan Huygens first described them as a ring in 1655.

    Source: Rings of Saturn (Wikipedia) · Fact card

83. Saturn’s moon Titan has a thicker atmosphere than Earth.

    It is the only moon with a dense atmosphere, made mostly of nitrogen.

    Source: Titan (moon) (Wikipedia) · Fact card

84. Titan has lakes and seas of liquid methane.

    It is the only place besides Earth known to have stable liquid on its surface.

    Source: Lakes of Titan (Wikipedia) · Fact card

85. A probe landed on Titan in 2005.

    The European Huygens probe touched down after a parachute descent, the most distant landing ever made.

    Source: Huygens (spacecraft) (Wikipedia) · Fact card

86. Saturn’s moon Enceladus shoots water into space.

    Geysers at its south pole spray water from an ocean under the ice, and the spray feeds Saturn’s E ring.

    Source: Enceladus (Wikipedia) · Fact card

87. There is a giant hexagon-shaped storm at Saturn’s north pole.

    Each side of the six-sided jet stream is longer than Earth is wide.

    Source: Saturn’s hexagon (Wikipedia) · Fact card

88. A day on Saturn lasts about 10.5 hours.

    Its fast spin makes the planet bulge noticeably at the equator.

    Source: Saturn (Wikipedia) · Fact card

89. A year on Saturn lasts about 29 Earth years.

    It orbits the Sun at an average of about 1.4 billion kilometers.

    Source: Saturn (Wikipedia) · Fact card

90. NASA crashed its Cassini spacecraft into Saturn on purpose.

    After 13 years orbiting Saturn, Cassini dove into the planet in 2017 so it could not contaminate moons that might support life.

    Source: Cassini-Huygens (Wikipedia) · Fact card

91. Winds on Saturn can reach about 1,800 km/h.

    The fastest winds blow around the equator.

    Source: Saturn (Wikipedia) · Fact card

92. Saturn is made mostly of hydrogen and helium.

    Like Jupiter, it has no solid surface to stand on.

    Source: Saturn (Wikipedia) · Fact card

93. Saturn’s moon Mimas looks like the Death Star.

    A giant crater, Herschel, covers almost a third of its width.

    Source: Mimas (moon) (Wikipedia) · Fact card

94. Saturn’s moon Iapetus is two-toned.

    One side is dark as coal and the other is bright as snow.

    Source: Iapetus (moon) (Wikipedia) · Fact card

95. Saturn is named after the Roman god of farming and wealth.

    The day Saturday is also named after Saturn.

    Source: Saturn (mythology) (Wikipedia) · Fact card

96. Saturn was the farthest planet known in ancient times.

    It is the most distant planet easily seen without a telescope.

    Source: Saturn (Wikipedia) · Fact card

97. Saturn’s rings may be young, in planetary terms.

    Some measurements suggest they could be a few hundred million years old, though this is still debated.

    Source: Rings of Saturn (Wikipedia) · Fact card

98. Saturn’s rings are slowly raining onto the planet.

    Ice particles fall into Saturn’s atmosphere, so the rings are gradually losing material.

    Source: Rings of Saturn (Wikipedia) · Fact card

99. Pioneer 11 was the first spacecraft to visit Saturn, in 1979.

    Voyager 1 and Voyager 2 followed in 1980 and 1981.

    Source: Pioneer 11 (Wikipedia) · Fact card

100. Small "shepherd moons" keep some of Saturn’s rings in shape.

     Moons such as Prometheus and Pandora help confine the narrow F ring.

     Source: Rings of Saturn (Wikipedia) · Fact card

101. Saturn has giant storms that circle the whole planet.

     A huge storm in 2010 and 2011 stretched all the way around the northern hemisphere.

     Source: Great White Spot (Wikipedia) · Fact card

102. Gravity at Saturn’s cloud tops is close to Earth’s.

     Despite its huge mass, Saturn is so wide and light that its gravity at the cloud tops is only slightly stronger than ours.

     Source: Saturn (Wikipedia) · Fact card

103. NASA plans to fly a drone on Titan.

     The Dragonfly rotorcraft mission is planned to launch in 2028 and explore Titan’s surface.

     Source: Dragonfly (Titan space probe) (Wikipedia) · Fact card

104. Saturn’s moon Hyperion looks like a giant sponge.

     Its porous, irregular body tumbles chaotically as it orbits.

     Source: Hyperion (moon) (Wikipedia) · Fact card

105. Neptune is the eighth and farthest planet from the Sun.

     It orbits about 4.5 billion kilometers from the Sun, around 30 times farther than Earth.

     Source: Neptune (Wikipedia) · Fact card

106. A year on Neptune lasts about 165 Earth years.

     It has completed just one orbit since it was discovered in 1846.

     Source: Neptune (Wikipedia) · Fact card

107. A day on Neptune lasts about 16 hours.

     Like the other giant planets, it spins much faster than Earth.

     Source: Neptune (Wikipedia) · Fact card

108. Neptune is an "ice giant".

     Below its atmosphere it is made largely of water, ammonia and methane in hot, dense forms rather than gas.

     Source: Ice giant (Wikipedia) · Fact card

109. Methane helps make Neptune blue.

     Methane in the atmosphere absorbs red light and reflects blue.

     Source: Neptune (Wikipedia) · Fact card

110. Neptune is about four times as wide as Earth.

     It is about 17 times as massive as Earth.

     Source: Neptune (Wikipedia) · Fact card

111. Neptune was first seen through a telescope in 1846.

     Johann Galle spotted it in Berlin using predictions by Urbain Le Verrier, based on wobbles in Uranus’s orbit.

     Source: Discovery of Neptune (Wikipedia) · Fact card

112. Galileo saw Neptune in 1612 but thought it was a star.

     His notes show he recorded it but did not realize it was a planet.

     Source: Discovery of Neptune (Wikipedia) · Fact card

113. Only one spacecraft has ever visited Neptune.

     Voyager 2 flew past in August 1989 and sent back the first close-up images.

     Source: Voyager 2 (Wikipedia) · Fact card

114. Neptune had a storm as big as Earth, the Great Dark Spot.

     Voyager 2 photographed it in 1989; by 1994 the Hubble Space Telescope found it had disappeared.

     Source: Great Dark Spot (Wikipedia) · Fact card

115. Neptune’s largest moon, Triton, orbits backward.

     Triton circles opposite to Neptune’s spin, a sign it was probably captured from the Kuiper Belt.

     Source: Triton (moon) (Wikipedia) · Fact card

116. Triton has geysers of nitrogen.

     Voyager 2 saw dark plumes rising several kilometers above its frozen surface.

     Source: Triton (moon) (Wikipedia) · Fact card

117. Triton is one of the coldest places measured in the solar system.

     Its surface is about minus 235°C.

     Source: Triton (moon) (Wikipedia) · Fact card

118. Triton is slowly spiraling toward Neptune.

     In billions of years it may be torn apart and form a ring.

     Source: Triton (moon) (Wikipedia) · Fact card

119. Neptune has 16 known moons.

     Triton holds more than 99% of the mass of all of them combined.

     Source: Moons of Neptune (Wikipedia) · Fact card

120. Neptune has dark, faint rings.

     The rings are named after astronomers linked to its discovery, including Galle, Le Verrier and Adams.

     Source: Rings of Neptune (Wikipedia) · Fact card

121. Neptune’s outer ring has clumps named Liberty, Equality and Fraternity.

     The arcs in the Adams ring carry the French revolutionary motto, in French: Liberté, Égalité and Fraternité.

     Source: Rings of Neptune (Wikipedia) · Fact card

122. Neptune gives off more than twice the heat it gets from the Sun.

     Its internal heat source may drive its extreme winds.

     Source: Neptune (Wikipedia) · Fact card

123. Neptune has seasons that last about 40 years each.

     Its axis is tilted about 28 degrees, similar to Earth’s, and its year is 165 Earth years long.

     Source: Neptune (Wikipedia) · Fact card

124. Neptune is named after the Roman god of the sea.

     Its astronomical symbol is a trident.

     Source: Neptune (mythology) (Wikipedia) · Fact card

125. Neptune became the farthest planet again in 2006.

     When Pluto was reclassified as a dwarf planet, Neptune became the outermost planet.

     Source: Pluto (Wikipedia) · Fact card

126. Pluto is sometimes closer to the Sun than Neptune.

     Pluto’s oval orbit crossed inside Neptune’s from 1979 to 1999, but the two never collide.

     Source: Pluto (Wikipedia) · Fact card

127. It may rain diamonds inside Neptune.

     Lab experiments suggest the pressure deep inside ice giants could turn carbon into diamonds that sink toward the core.

     Source: Neptune (Wikipedia) · Fact card

128. Gravity at Neptune’s cloud tops is a little stronger than Earth’s.

     It is about 1.1 times Earth’s gravity.

     Source: Neptune (Wikipedia) · Fact card

129. Sunlight takes about four hours to reach Neptune.

     From Neptune, the Sun looks like a very bright star.

     Source: Neptune (Wikipedia) · Fact card

130. Neptune has its own Trojan asteroids.

     Small bodies share its orbit, gathered ahead of and behind the planet.

     Source: Neptune trojan (Wikipedia) · Fact card

131. Neptune’s moon Nereid has one of the most stretched-out orbits of any moon.

     Its distance from Neptune varies enormously during each orbit.

     Source: Nereid (moon) (Wikipedia) · Fact card

132. Venus is the second planet from the Sun.

     It is the closest planet to Earth in size and is sometimes called Earth’s twin.

     Source: Venus (Wikipedia) · Fact card

133. Venus spins backward.

     Compared with most planets, it rotates in the opposite direction, so the Sun rises in the west there.

     Source: Venus (Wikipedia) · Fact card

134. The air pressure on Venus is about 90 times Earth’s.

     That is like being about 900 meters under the sea on Earth.

     Source: Atmosphere of Venus (Wikipedia) · Fact card

135. Venus is covered in clouds of sulfuric acid.

     The thick clouds reflect sunlight, which is one reason Venus shines so brightly.

     Source: Atmosphere of Venus (Wikipedia) · Fact card

136. Venus’s atmosphere is about 96% carbon dioxide.

     This creates a runaway greenhouse effect that traps heat.

     Source: Atmosphere of Venus (Wikipedia) · Fact card

137. The surface of Venus is about 465°C.

     That is hot enough to melt lead, day and night.

     Source: Venus (Wikipedia) · Fact card

138. Venus is called the morning star and the evening star.

     It is often visible just before sunrise or just after sunset, and ancient people sometimes thought these were two different objects.

     Source: Venus (Wikipedia) · Fact card

139. The first spacecraft to land on another planet landed on Venus.

     The Soviet Venera 7 probe touched down in 1970 and sent signals from the surface.

     Source: Venera 7 (Wikipedia) · Fact card

140. The first photos from another planet’s surface came from Venus.

     Venera 9 sent back images in 1975 before the heat and pressure destroyed it.

     Source: Venera 9 (Wikipedia) · Fact card

141. No lander has survived on Venus for more than about two hours.

     The record is held by Venera 13 in 1982, which lasted about 127 minutes.

     Source: Venera 13 (Wikipedia) · Fact card

142. Venus sometimes crosses in front of the Sun.

     Transits of Venus come in pairs eight years apart, more than a century apart. The last was in 2012 and the next is in 2117.

     Source: Transit of Venus (Wikipedia) · Fact card

143. Venus is named after the Roman goddess of love and beauty.

     It is the only planet named after a female figure.

     Source: Venus (Wikipedia) · Fact card

144. Venus has more volcanoes than any other planet.

     Radar maps show hundreds of large volcanoes, and recent studies suggest some may still be active.

     Source: Volcanism on Venus (Wikipedia) · Fact card

145. Venus’s surface was mapped by radar.

     NASA’s Magellan spacecraft mapped almost the whole surface through the clouds in the early 1990s.

     Source: Magellan (spacecraft) (Wikipedia) · Fact card

146. Venus’s clouds race around the planet in about four days.

     The upper atmosphere moves about 60 times faster than the planet turns, a pattern called super-rotation.

     Source: Atmosphere of Venus (Wikipedia) · Fact card

147. A year on Venus lasts about 225 Earth days.

     Its slow spin means one Venus day lasts about 243 Earth days.

     Source: Venus (Wikipedia) · Fact card

148. Venus comes closer to Earth than any other planet.

     At its closest it is about 38 million kilometers away.

     Source: Venus (Wikipedia) · Fact card

149. Venus has phases like the Moon.

     Galileo’s observations of these phases in 1610 supported the idea that planets orbit the Sun.

     Source: Phases of Venus (Wikipedia) · Fact card

150. Almost every feature on Venus is named after a woman.

     The one main exception is Maxwell Montes, its highest mountain, named after physicist James Clerk Maxwell.

     Source: Maxwell Montes (Wikipedia) · Fact card

151. Scientists have debated for decades whether Venus has lightning.

     Spacecraft have recorded radio bursts that may be lightning, but the evidence is still argued over.

     Source: Atmosphere of Venus (Wikipedia) · Fact card

152. A 2020 study sparked debate about possible life in Venus’s clouds.

     Astronomers reported phosphine, a gas linked to life on Earth, but later studies disputed the detection.

     Source: Phosphine (Wikipedia) · Fact card

153. New missions to Venus are planned.

     NASA’s VERITAS and DAVINCI and Europe’s EnVision are being developed to study the planet.

     Source: EnVision (Wikipedia) · Fact card

154. On Venus, the time from one sunrise to the next is about 117 Earth days.

     Its backward spin and orbit combine to give a solar day shorter than its rotation.

     Source: Venus (Wikipedia) · Fact card

155. You cannot see Venus’s surface with a normal telescope.

     Its clouds hide the surface completely; we see it only with radar or by landing.

     Source: Venus (Wikipedia) · Fact card

156. Venus has strange flat volcanoes called pancake domes.

     They were formed by thick, sticky lava and can be tens of kilometers across.

     Source: Pancake dome (Wikipedia) · Fact card

157. Much of Venus’s surface may be relatively young.

     Few craters suggest the surface was largely resurfaced by volcanic activity within the last several hundred million years.

     Source: Geology of Venus (Wikipedia) · Fact card