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Ten Largest Moons in the Solar System Quiz
In 2024, the International Astronomical Union (IAU) officially recognizes 288 planetary moons orbiting the solar system's eight worlds, according to NASA. You need to put the ten largest of these moons in order.
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Mobile instructions: Press on an answer on the right. Then, press on the question it matches on the left.
(a) Drag-and-drop from the right to the left, or (b) click on a right
side answer, and then click on its destination box to move it.
Name the ten largest moons in the Solar System in terms of size from the largest to the smallest of the ten.
What's the Correct Order?
Choices
1. (Largest)
Titan
2.
Earth's Moon
3.
Ganymede
4.
Titania
5.
Europa
6.
Rhea
7.
Io
8.
Callisto
9.
Oberon
10. (Smallest of the top ten)
Triton
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Quiz Answer Key and Fun Facts
1. Ganymede
Discovered in 1610 by Galileo Galilei, Ganymede is the largest moon in the solar system has a diameter of 5,270 km (3,275 miles), which is even larger than Mercury.
It has a thick icy crust with a dense iron core. Below the icy surface, it contains an ocean which is estimated to contain more water than all the oceans on Earth combined. It is the only moon in the solar system with a magnetic field which is produced by its iron core.
It takes seven days to complete one orbit around Jupiter, at a mean distance of 1.07 million km (668,750 miles).
2. Titan
Saturn's largest moon, Titan with a diameter 5,150 km (3,200 miles) was discovered by the astronomer Christiaan Huygens in 1655. In 1944, the astronomer Gerard Kuiper discovered that it has a significant atmosphere with an intriguing surface. Beneath the surface, it is a dense atmosphere of hydrocarbons.
In 2005, the Cassini-Huygens mission landed successfully on Titan. The images taken by the probe revealed it looked more like the Earth than a typical moon. The exterior was covered in rivers, streams, lakes and seas. However, temperatures on Titan are far too cold for water to exist in liquid form. Instead, the liquid on Titan's surface is liquid methane and ethane. It even rains liquid methane on the surface. Titan and Earth are the only two known worlds in the solar system where it rains.
It takes 16 days to make one complete orbit around Saturn, at a mean distance of 1.2 million km (750,000 miles).
3. Callisto
Discovered by Galileo in 1610, Callisto with a diameter of 4,820 km (2,995 miles) is the second largest moon of Jupiter.
Its surface is heavily cratered, and it is likely the least active world in the solar system, with little to no history of geologic activity. There is virtually no change over its 4.5-billion-year history. Callisto has the oldest known surface in the solar system.
It takes 17 days to make one complete orbit around Jupiter, at a mean distance of 1.88 million km (1.175 million miles), making it the farthest moon from Jupiter.
4. Io
Io with the diameter of 3,463 km (2,264 miles) is one of the four Galilean moons of Jupiter discovered by Galileo in 1610. In the late 1970s, images taken the Voyager flybys revealed the surface was entirely devoid of impact craters, which is strange given the number of craters on other moons around Jupiter.
The surface is covered in various colors, including yellow, red, and green, which made it looked completely different compared to any other moon. Images also revealed that it is the most volcanically active world in the solar system, having over 400 active volcanoes.
Io orbits Jupiter at a distance of 421,700 km (263,125 miles) and completes one orbit every 1.8 Earth days.
5. Earth's Moon
Moon's diameter is 3,475 km (2,195 miles). The moon is a natural satellite that orbits the Earth, which is widely believed to have formed around 4.5 billion years ago due to a collision between the Earth and another planet. The debris from this collision entered into Earth's orbit and eventually coalesced to form the moon. In terms of composition, the moon is similar to the Earth in some ways.
The Moon takes about one month to orbit Earth (27.3 days to complete a revolution, but 29.5 days to change from new moon to new moon), at a mean distance of 382,000 km (238,750 miles).
6. Europa
Europa has a diameter of 3,122 km (1,940 miles). It was discovered by Galileo in 1610 with his homemade telescope.
It appears brighter than our Moon. The surface is made of water ice and so it reflects 5.5 times the sunlight than our Moon does. The atmosphere is very thin and mostly made of oxygen, with a surface temperature -160°C (-256°F) at the equator and -220°C (-364°F) at the poles. It is believed that it has a large salty ocean beneath its icy surface, which contain twice as much water as the oceans on Earth.
It takes 3.5 days to complete one revolution around Jupiter, at a mean distance of 670,900 km (419,313 miles).
7. Triton
Triton is the largest of Neptune's 13 moons has a diameter with a diameter of 2,707 km (1,682 miles). It was discovered on Oct. 10, 1846 by British astronomer William Lassell, just 17 days after Neptune itself was discovered.
The surface is covered in frozen nitrogen and has few impact craters, smooth volcanic plains, mounds and round pits. The atmosphere is thin, made up of nitrogen, methane and carbon monoxide. It has a surface temperature of -235°C (-391°F). It is a geologically active worlds in the solar system, with a complex geological history of young cryovolcanic and tectonic terrains.
It moves in a retrograde orbit, takes 5.877 days to complete one revolution around Neptune, at a mean distance of 354,800 km (221,750 miles).
8. Titania
Titania has a diameter of 1,578 km (980 miles) and is the largest moon of Uranus, It was discovered in 1787 by William Herschel, who had also discovered Uranus.
It is neutral gray in color, with a system of fault valleys that break the crust in two directions. There are many impact craters and a ring-shaped impact basin. There is carbon dioxide in the atmosphere.
It takes 8.706 days to complete one orbit around Uranus at a mean distance of 435,840 km (272,400 miles).
9. Rhea
Rhea has a diameter of 1,529 km (950 miles). On 23 December 1672, Rhea was discovered by Giovanni Domenico Cassini with a 10.4 m telescope.
It is the second largest moon of Saturn, made up of about 75% water ice and 25% rock. The surface is heavily cratered, especially on the leading side. It was discovered by the Cassini spacecraft too have rings; the first-time rings were discovered around a moon. It has an extremely thin atmosphere with trace amounts of carbon dioxide and oxygen. The surface temperature ranges from -174°C (-281°F) in sunlit areas to -220°C (-364°F) in shaded areas.
It takes 4.52 days to complete a rotation around Saturn, at a mean distance of 527,000 km (329,375 miles).
10. Oberon
Oberon's diameter is 1,523 km (946 km). It was discovered by Sir William Herschel in 1787.
It is the outermost satellite and second largest moon of Uranus. It is made up roughly equal parts ice and rock, with a density of 1.68 g/cm3 (0.06 lb/in3). The surface is red in color, with many impact craters and dark patches. The surface is possibly shaped by asteroid and comet impacts over millions of years. There is a possibility that it has a liquid ocean layer at the core-mantle boundary, about 40 km (25 miles) thick and a temperature of about -93°C (-135°F). There is probably presence of methane, ammonia and nitrogen.
It takes 13.46 days to orbit around Uranus, at a mean distance of 582,600 km (364,125 miles).
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