jupiters moons and rings
Jupiter has a very large number of moons 63 have been discovered so far. Four are big enough and bright enough to be seen from Earth, using no more than a pair of binoculars. These moons Io, Europa, Ganymede, and Callisto were first discovered by Galileo in 1610, so they are sometimes referred to as the Galilean moons (Figure 1.4). The Galilean moons are larger than the dwarf planets Pluto, Ceres, and Eris. Ganymede is not only the biggest moon in the solar system; it is even larger than the planet Mercury! Scientists are particularly interested in Europa because it may be a place to find extraterrestrial life. What features might make a satellite so far from the Sun a candidate for life? Although the surface of Europa is a smooth layer of ice, there is evidence that there is an ocean of liquid water underneath (Figure 1.5). Europa also has a continual source of energy it is heated as it is stretched and squashed by tidal forces from Jupiter. Numerous missions have been planned to explore Europa, including plans to drill through the ice and send a probe into the ocean. However, no such mission has yet been attempted. In 1979, two spacecraft Voyager 1 and Voyager 2 visited Jupiter and its moons. Photos from the Voyager missions showed that Jupiter has a ring system. This ring system is very faint, so it is difficult to observe from Earth. This composite image shows the four Galilean moons and their sizes relative to the Great Red Spot. From top to bottom, the moons are Io, Europa, Ganymede, and Callisto. Jupiters Great Red Spot is in the background. Sizes are to scale. Click image to the left or use the URL below. URL:
Jupiter is enormous, the largest object in the solar system besides the Sun. Although Jupiter is over 1,300 times Earths volume, it has only 318 times the mass of Earth. Like the other gas giants, it is much less dense than Earth. Because Jupiter is so large, it reflects a lot of sunlight. Jupiter is extremely bright in the night sky; only the Moon and Venus are brighter (Figure 1.1). This brightness is all the more impressive because Jupiter is quite far from the Earth 5.20 AUs away. It takes Jupiter about 12 Earth years to orbit once around the Sun.
a stormy atmosphere
The upper layer of Jupiters atmosphere contains clouds of ammonia (NH3 ) in bands of different colors. These bands rotate around the planet, but also swirl around in turbulent storms. The Great Red Spot (Figure 1.3) is an enormous, oval-shaped storm found south of Jupiters equator. This storm is more than three times as wide as the entire Earth. Clouds in the storm rotate in a counterclockwise direction, making one complete turn every six days or so. The Great Red Spot has been on Jupiter for at least 300 years, since astronomers could first see the storm through telescopes. Do you think the Great Red Spot is a permanent feature on Jupiter? How could you know? This image of Jupiters Great Red Spot (upper right of image) was taken by the Voyager 1 spacecraft. The white storm just below the Great Red Spot is about the same diameter as Earth.
a ball of gas and liquid
Astronauts trying to land a spaceship on the surface of Jupiter would find that there is no solid surface at all! Jupiter is made mostly of hydrogen, with some helium, and small amounts of other elements (Figure 1.2). Jupiters atmosphere is composed of hydrogen and helium. Deeper within the planet, pressure compresses the gases into a liquid. Some evidence suggests that Jupiter may have a small rocky core of heavier elements at its center. This image of Jupiter was taken by Voy- ager 2 in 1979. The colors were later enhanced to bring out more details.
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which is the nearest of the gas giant planets to the sun?
a) pluto b) uranus --> c) jupiter d) none of the above
a) has highly pressurized ices at its center. --> b) is made mostly of hydrogen and some helium. c) has a solid surface that a spacecraft could land on. d) all of the above.
jupiter is so large that it makes its own light.
a) true --> b) false
jupiter is 5.2 times as from the sun as the earth is.
--> a) true b) false
a) a faint ring system b) at least 63 moons c) some evidence for a small rocky core. --> d) all of the above.
the galilean moons
a) are io, europa, ganymede and callisto b) were discovered by galileo through his telescope in 1610. c) are larger than the dwarf planet pluto. --> d) all of the above.
what is the great red spot found on jupiter?
a) a mark left over from reactions of hydrogen, helium, and ammonia. b) iron-oxide dust blowing in a giant storm. c) a band of red rocks. --> d) a giant storm in the atmosphere.
how do scientists know the minimum length of time the great red spot has been on jupiter?
a) it was first seen through the naked eye and recorded more than 400 years ago. b) they have done calculations and they know a feature of that type would last at least 750 years. --> c) it has been at least 300 years since it was seen through a telescope. d) none of these.
jupiters moon, europa, is a place to search for extraterrestrial life because it
--> a) may have a liquid water ocean beneath its solid ice surface. b) has heat from the sun as an energy source. c) emits organic molecules into its atmosphere. d) all of these.
jupiters atmosphere contains
a) thick carbon dioxide, which causes runaway greenhouse effect. --> b) ammonia clouds in different colored bands. c) methane gas from decaying life. d) all of these.
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