3/25/2020 Jupiter Solar System Sites that might support life! Jupiter and its Satellites Juno, Io & Europa Dr. Alka Misra Department of Mathematics & Astronomy University of Lucknow, Lucknow • • As massive as Jupiter is, though, it is Named after the most powerful god of still some 1000 times less massive the Roman pantheon, Jupiter is by far than the Sun. the largest planet in the solar system. • This makes studies of Jupiter all the • Ancient astronomers could not have more important, for here we have an known the planet's true size, but their object intermediate in size between the Sun and the terrestrial planets. choice of names was very appropriate. • It is 1.9×1027kg, or 318 Earth masses. • Jupiter is the third-brightest object in the night sky (after the Moon and Venus), making it very easy to locate • Jupiter has more than twice the and study mass of all the other planets combined. • Studies of the planet's internal • Knowing Jupiter's distance and structure indicate that Jupiter must angular size, we can easily be composed primarily of hydrogen determine its radius. and helium. • It is 71,400 km, or 11.2 Earth • Doppler-shifted spectral lines prove radii. that the equatorial zones rotate a little faster (9h50m period) than the • From the size and mass, we derive higher latitudes (9h56m period). an average density of 1300 kg/m3 (1.3 g/cm3) for the planet. • Thus, Jupiter exhibits differential rotation 1 3/25/2020 • Jupiter has the fastest rotation rate Atmosphere of the Jupiter of any planet in the solar system, and this rapid spin has altered • Jupiter is visually dominated by two features. Jupiter's shape. • 1. A series of ever-changing atmospheric bands arranged parallel to the equator. • A spinning object tends to develop a bulge around its midsection. • 2. An oval atmospheric blob called the Great Red Spot, or often just the "Red Spot. • Jupiter's equatorial radius-71,400 km exceeds its polar radius -66,800 km • The cloud bands display many colors--pale by about 6.5 percent. yellows, light blues, deep browns, drab/dull tans, and vivid/bright reds among others. • Bands Feature Great Red Spot Scientists believe that chemical compounds in Jupiter's atmosphere create these different colors • But the detailed chemistry is still not completely understood. • The Red Spot is one of many features associated with Jupiter's weather. • It seems to be an Earth-sized hurricane that has persisted for hundreds of years. ATMOSPHERIC COMPOSITION • Together they make up over 99% of • Spectroscopic studies of sunlight Jupiter's atmosphere. reflected from Jupiter gave scientists their first look at the • Scientists generally accept that planet's atmospheric composition. these two gases also make up the bulk of the planet's interior. • Radio, infrared, and ultraviolet observations later provided more • Small amounts of atmospheric details. methane, ammonia, and water vapor • The most abundant gas is molecular are also found. hydrogen (86.1%), followed by helium (13.8 percent). 2 3/25/2020 Internal Energy Source of Jupiter • Jupiter actually emits about twice • It is not the decay of radioactive as much energy as it receives from elements within the planet--that the Sun. must be occurring, but not at nearly the rate necessary to produce the temperature we record. • Thus, unlike any of the terrestrial planets, Jupiter must have its own internal heat source. • Nor is it the process that generates energy in the Sun, nuclear fusion-- the temperature in Jupiter's • What is responsible for Jupiter's interior, high as it is, is far too low extra energy? for that. • Instead, astronomers theorize that the source of Jupiter's excess energy • Despite the huge amounts of is the slow escape of gravitational energy involved--Jupiter's energy energy released during the planet's emission is about 4x1017 watts formation. more than it receives from the Sun--the energy loss is quite slight • compared with the planet's total As the planet took shape, some of its energy. energy was converted into heat in the interior. • A simple calculation indicates that the average temperature of • That heat is still slowly leaking out the interior of Jupiter falls by only through the planet's heavy about a millionth of a kelvin per atmospheric blanket, resulting in the year excess emission we observe. Moons of the Jupiter—79 (2019) • Moving outward from Jupiter, the • In many ways, the entire Jupiter system four are named Io, Europa, resembles a miniature solar system. Ganymede, and Callisto, after the mythical attendants of the Roman • Jupiter has 53 named moons and another 26 God Jupiter. awaiting official names. Combined, scientists now think Jupiter has 79 moons. • Galilean moons correspond to the terrestrial planets. Their orbits are • Its four largest moons--the Galilean direct (i.e., in the same sense as satellites--are each comparable in size to Jupiter's rotation), roughly circular, Earth's Moon. & lie close to Jupiter's equatorial plane. 3 3/25/2020 • Many astronomers think that the • They range in size from slightly smaller formation of Jupiter and the Galilean than Earth's Moon (Europa) to slightly satellites may in fact have mimicked larger than Mercury (Ganymede). on a small scale the formation of the Sun and the inner planets. • The parallel with the inner solar system continues with the realization that their densities decrease with increasing • For that reason, studies of the distance from Jupiter. Galilean moon system may provide us • It is quite likely that the inner two with valuable insight into the Galilean moons, Io and Europa, have a processes that created our own world. rocky composition, possibly similar to the crusts of the terrestrial planets. Atmosphere of Jupiter • Jupiter is much larger than Earth and considerably less dense: its volume is that • Jupiter's upper atmosphere is about 88–92% of about 1,321 Earths, but it is only 318 hydrogen and 8–12% helium by percent volume of gas molecules. times as massive. • The atmosphere contains trace amounts: • Jupiter has the largest planetary of methane, water vapor, ammonia, and silicon- atmosphere in the Solar System, spanning based compounds. There are also traces over 5,000 km in altitude. of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, and sulfur. • The outermost layer of the atmosphere • Is there water on Jupiter?” has been asked contains crystals of frozen ammonia. many times. • Through infrared and ultraviolet measurement, • The answer is yes, there is a small amount trace amounts of benzene and of water, but it is not ”on” Jupiter. It is in the other hydrocarbons have also been found. form of water vapor in the cloud tops. • Jupiter should have more oxygen than the Sun for water What's It Like Inside Jupiter? • The oxygen would have combined with the more • It's really hot inside Jupiter! No one knows than abundant hydrogen in the Jovian atmosphere, exactly how hot, but scientists think it could thus making water a significant component. be about 43,000°F (24 ,000°C) near Jupiter's center, or core. • The trouble is that the Galileo space craft found that Jupiter’s atmosphere contains less oxygen than the • Jupiter is made up almost entirely of Sun; therefore, water is a minor trace element in the hydrogen and helium. On the surface of atmosphere. Jupiter–and on Earth–those elements are gases. However inside Jupiter, hydrogen can • That does not mean that there is not significant be a liquid, or even a kind of metal. amounts of water elsewhere in the Jovian system. • These changes happen because of the • A few of Jupiter’s moons have been found to have tremendous temperatures water or water ice in their atmosphere or on their and pressures found at the core. surface. 4 3/25/2020 How much pressure would you find at the What is pressure? center of Jupiter? Imagine if you swam to the bottom • Have you ever gone swimming at the deep end of a of the Pacific Ocean. You would pool? Did you notice that your ears started to hurt a feel more than 16,000 pounds of little bit when you were under water? The deeper you force pressing down on every dive, the more water there is on top of you. All of that square inch of your body. That is water presses on your body–and that's pressure. approximately the weight of four • The same type of pressure happens in Jupiter's core. cars! Under low pressure, particles of hydrogen and helium, The pressure at the center of called molecules, have lots of room to bounce around. Jupiter is much higher. At Jupiter's This is when hydrogen and helium are gases. core, you would feel as much as 650 million pounds of pressure • However, the weight of all this hydrogen and helium is pressing down on every square really heavy. This weight presses down toward the inch of your body. That would be planet's core, creating high pressure. The molecules run like having approximately 160,000 out of room to bounce around, so instead, they slow cars stacked up in every direction down and crowd together. This creates a liquid. all over your body! What lies at the very center of Jupiter? Is it possible for life on Jupiter? • There is no way that life as we • At the moment, scientists aren't 100% understand it could exist on the sure. gas giant. • It may be that the planet has a solid core • The possibility of life within the that is bigger than Earth. But some Jovian system is still being explored.