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What is a planet? • http://www.youtube.com/watch?v=RQU 2Q-CU6lY • What is a planet? 1. orbits the sun 2. nearly round shape because its own gravity is sufficient 3. neighborhood is cleared because its gravity is sufficient Copyright © 2010 Pearson Education, Inc. What is a dwarf planet? 1. orbits the sun 2. nearly round shape because its own gravity is sufficient 3. neighborhood is not cleared because its gravity is not sufficient 4. Not a moon of another planet Copyright © 2010 Pearson Education, Inc. Chapter 7 The Jovian Planets Now we shift gears from our local rock planets to the outer gas giants. We have in our own solar system 4 examples of each of the types of planets! Why is Jupiter so happy? Copyright © 2010 Pearson Education, Inc. Why name planets after Greek/Roman gods and goddesses? • • • • Everything important got a god associated with it. Why Roman took over Greek names? What about dozens of other cultures and myths? Did the Greeks think the god Jupiter was literally in that speck of light? • Modern convention in our solar system • Rules governed by the IAU http://www.iau.org/ Copyright © 2010 Pearson Education, Inc. Mercury is the god of commerce, travel and thievery in Roman mythology. The planet probably received this name because it moves so quickly across the sky. Venus is the Roman goddess of love and beauty. The planet is aptly named since it makes a beautiful sight in the sky, with only the Sun and the Moon being brighter. Earth is the only planet whose English name does not derive from Greek/Roman mythology. The name derives from Old English and Germanic. There are, of course, many other names for our planet in other languages. Mars is the Roman god of War. The planet probably got this name due to its red color. Jupiter was the King of the Gods in Roman mythology, making the name a good choice for what is by far the largest planet in our solar system. Saturn is the Roman god of agriculture. Uranus is the ancient Greek deity of the Heavens, the earliest supreme god. Neptune, was the Roman god of the Sea. Given the beautiful blue color of this planet, the name is an excellent choice! Pluto is the Roman god of the underworld in Roman mythology. Perhaps the planet received this name because it's so far from the Sun that it is in perpetual darkness. Copyright © 2010 Pearson Education, Inc. The planets in East Asia cultures For the five true planets, their element's Chinese character, hanzi(汉字), is also part of the names of weekdays in Japanese and Korean, complemented with Sunday and Monday.10 However, Chinese and Vietnamese number the days other than Sunday.11 The cycles of the Chinese calendar are linked to the orbit of Jupiter, there being 12 sacred beasts in the Chinese dodecannualar geomantic and astrological cycle, and 12 years in the orbit of Jupiter. Copyright © 2010 Pearson Education, Inc. Chinese/J English Associate apanese Chinese Japanese Korean Vietname Name d element Character pinyin romaji Name se Name s 수성 Mercury water Shuǐxīng Suisei (Suseong Sao Thủy 水星 ) Sao Kim, also "Sao Mai" as 금성 "morning metal/gol Venus Jīnxīng Kinsei (Geumse star" and 金星 d ong) "Sao Hôm" as "evening star" 화성 Mars fire Huǒxīng Kasei (Hwaseo Sao Hỏa 火星 ng) 목성 Jupiter wood Mùxīng Mokusei (Mokseo Sao Mộc 木星 ng) 토성 Copyright © 2010 Pearson Education, Inc. Saturn earth Tǔxīng Dosei (Toseong Sao Thổ 土星 Old astronomi cal names[12] Chénxīng (辰星) Tàibái (太 白) Yínghuò ( 熒惑) Suì (歲) Zhènxīng Units of Chapter 7 Observations of Jupiter and Saturn The Discoveries of Uranus and Neptune Bulk Properties of the Jovian Planets Jupiter’s Atmosphere The Atmospheres of the Outer Jovian Worlds Jovian Interiors Summary of Chapter 7 Copyright © 2010 Pearson Education, Inc. Our mission • Understand the properties of these 4 planets • Relate their properties to their origin • Compare them to each other • Compare them to the rocky inner planets • Be able to find Jupiter in the sky, and see its moons with binocs Copyright © 2010 Pearson Education, Inc. 7.1 Observations of Jupiter and Saturn Jupiter can be imaged well from Earth, even with a small telescope. Do you have binoculars? Here: Jupiter with its Galilean moons Copyright © 2010 Pearson Education, Inc. 19 jan..7.1 Observations of Jupiter and Saturn True-color image of Jupiter This image is from Hubble, but much of our Jupiter knowledge is from the Galileo probe which cost $1.6b over 16 years http://www.dailymotion.com/vide o/xeaio4_learn-about-thediscoveries-of-the_tech Copyright © 2010 Pearson Education, Inc. 7.1 Observations of Jupiter and Saturn Natural-color image of Saturn https://www.youtube.com/watch ?v=AyFMPdHU1n0 stop at 5:50min Saturn has a thick atmosphere: why can we see it so clearly? Copyright © 2010 Pearson Education, Inc. 7.1 Observations of Jupiter and Saturn Cassini image of Jupiter, true color Copyright © 2010 Pearson Education, Inc. The Cassini mission: Wow! • Look at nasa site and wikipedia • Here’s a nice TED talk http://www.ted.com/talks/carolyn_porco _flies_us_to_saturn.html Copyright © 2010 Pearson Education, Inc. 23 Jan: 7.2 The Discoveries of Uranus and Neptune Uranus, in natural color. Note the absence of features and the prevalence of beauty. How was Uranus discovered? Copyright © 2010 Pearson Education, Inc. 7.2 The Discoveries of Uranus and Neptune Neptune in natural color How was Neptune discovered and how was this different from every other planet so far? Copyright © 2010 Pearson Education, Inc. 7.3 Bulk Properties of the Jovian Planets The Jovian planets are large and much less dense than the terrestrial planets; Saturn is less dense than water! None have a solid surface at all, although all have a dense core more massive than earth? explain that! Copyright © 2010 Pearson Education, Inc. 7.3 Bulk Properties of the Jovian Planets Where is the snowball that started each planet? Jovian planets, compared to Earth Copyright © 2010 Pearson Education, Inc. 7.3 Bulk Properties of the Jovian Planets Peculiarity of Uranus: Axis of rotation lies almost in the plane of its orbit. Seasonal variations are extreme. Copyright © 2010 Pearson Education, Inc. Do your research • In assigned pairs, make a model for all the jovian planets. Use available materials. Your model must show or allow demonstration of: • Interior structure • Atmosphere and clouds • Rings • Magnetosphere • Weather • Differential rotation Copyright © 2010 Pearson Education, Inc. Galileo spacecraft The Galileo spacecraft is the only one to have entered orbit around Jupiter, arriving in 1995 and studying the planet until 2003. • http://en.wikipedia.org/wiki/Galileo_(spacecraft) • On September 21, 2003, after 14 years in space and 8 years in the Jovian system, Galileo 's mission was terminated by sending the orbiter into Jupiter's atmosphere at a speed of over 48 kilometers (30 mi) per second, eliminating the possibility of contaminating local moons with terrestrial bacteria. Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. atmosphere Copyright © 2010 Pearson Education, Inc. 7.4 Jupiter’s Atmosphere Atmosphere has bright zones and dark belts. Zones are cooler, and are higher than belts. Simplified model is shown: We also see atmospheric rotation on earth: http://earth.nullschool.net/ Copyright © 2010 Pearson Education, Inc. 7.4 Jupiter’s Clouds No solid surface; take top of troposphere to be 0 km. Lowest cloud layer cannot be seen by optical telescopes. Measurements by Galileo probe show high wind speeds even at great depth – probably due to heating from planet, not from Sun. Why this composition? Copyright © 2010 Pearson Education, Inc. 7.4 Jupiter’s Atmosphere The Galileo probe descended into Jupiter’s atmosphere and returned valuable data. The arrow indicates its entry point. What is difference between gas atmosphere and clouds? Copyright © 2010 Pearson Education, Inc. 7.4 Jupiter’s Atmosphere Major visible features: Bands of clouds; Great Red Spot Shown actual size! Copyright © 2010 Pearson Education, Inc. A hurricane that is several hundred years old, 2x the diameter of earth 7.4 Jupiter’s Atmosphere Two examples of smaller storms merging, first into a smaller red spot, second into existing Great Red Spot Check: write a weather forcast for Jupiter…. Copyright © 2010 Pearson Education, Inc. 7.5 The Atmospheres of the Outer Jovian Worlds The atmosphere of Saturn is similar to that of Jupiter, except that Saturn is somewhat colder and its atmosphere is thicker. Why is Saturn colder than Jupiter? Give 2 reasons…… Copyright © 2010 Pearson Education, Inc. 7.5 The Atmospheres of the Outer Jovian Worlds Saturn’s atmosphere is similar to Jupiter’s, except pressure is lower. Why? It has three cloud layers. Cloud layers are thicker than Jupiter’s; see only top layer. Copyright © 2010 Pearson Education, Inc. 7.5 The Atmospheres of the Outer Jovian Worlds Saturn also has large storms, and bands. Copyright © 2010 Pearson Education, Inc. 7.5 The Atmospheres of the Outer Jovian Worlds Storms near Saturn’s equator Evidence of lightning Copyright © 2010 Pearson Education, Inc. 7.5 The Atmospheres of the Outer Jovian Worlds Enormous thunderstorm on Saturn Copyright © 2010 Pearson Education, Inc. 7.5 The Atmospheres of the Outer Jovian Worlds Rotation of Uranus can be measured by watching storms. Copyright © 2010 Pearson Education, Inc. 7.5 The Atmospheres of the Outer Jovian Worlds Neptune has storm systems similar to those on Jupiter, but fewer. The large storm system at top has disappeared in recent years. Copyright © 2010 Pearson Education, Inc. 7.6 Jovian Interiors No direct information is available about Jupiter’s interior, but its main components, hydrogen and helium, are quite well understood. The central portion is thought to be a rocky core. Copyright © 2010 Pearson Education, Inc. Metallic hyrdogen • • • • Isn’t hydrogen a gas? Squeezed between two pieces of diamond, hydrogen has been transformed into a metallic form believed to exist inside giant planets like Jupiter, scientists reported on Thursday. “You can see it becomes a lustrous, shiny material, which is what you expect for a metal,” said Isaac F. Silvera, a professor of physics at Harvard https://mobile.nytimes.com/2017/01/26/science/solid-metallic-hydrogen-harvardphysicists.html?rref=collection%2Ftimestopic%2FPhysics&action=click&contentCollection=s cience%C2%AEion=stream&module=stream_unit&version=latest&contentPlacement=1&pgt ype=collection&_r=0&referer= Copyright © 2010 Pearson Education, Inc. 7.6 Jovian Interiors Magnetic fields of Uranus and Neptune must not be produced by dynamos, as the other planets’ fields are. Interior structure of Uranus and Neptune, compared to that of Jupiter and Saturn: Copyright © 2010 Pearson Education, Inc. 7.6 Jovian Interiors Jupiter’s magnetosphere: Intrinsic field strength is 20,000 times that of Earth. Magnetosphere can extend beyond the orbit of Saturn. So catching solar wind in a magnetic field should lead to….? Copyright © 2010 Pearson Education, Inc. 7.6 Jovian Interiors Aurorae are seen on Jupiter, and have the same cause as those on Earth – the interaction of solar wind particles with the magnetosphere. Copyright © 2010 Pearson Education, Inc. 7.6 Jovian Interiors Uranus and Neptune both have substantial magnetic fields, but at a large angle to their rotation axes. The rectangle within each planet shows a bar magnet that would produce a similar field. Note that both Uranus’s and Neptune’s are significantly off center. Copyright © 2010 Pearson Education, Inc. Jovians in the news • P212. a cometary impact • Why did the comet breakup? • Did it break up when it went around the sun? • Why did it crash into Jupiter? • Copyright © 2010 Pearson Education, Inc. Summary of Chapter 7 • Jupiter and Saturn were known to the ancients; Uranus was discovered by chance, and Neptune was predicted from anomalies in the orbit of Uranus. • Jovian planets are large but not dense; they are fluid and display differential rotation. • Cloud layers have light zones and dark bands; wind pattern, called zonal flow, is stable. Copyright © 2010 Pearson Education, Inc. Summary of Chapter 7, cont. • Storms appear with regularity; the Great Red Spot of Jupiter has lasted for hundreds of years (that we know of). • Due to conductive interiors and rapid rotation, Jovian planets have large magnetic fields. • Jupiter, Saturn, and Neptune radiate more energy than they receive from the Sun. Copyright © 2010 Pearson Education, Inc. A few points in addition to know. • Why do they hold gas? Massive, magnetosphere, and far from sun • Why are they still losing heat? Still cooling from the big compression 4+ billion years ago • Properties of atmospheres? Layers, clouds, rotation Copyright © 2010 Pearson Education, Inc. How are jovians different from terrestrials to attain their structure? • Past frost line, snowball and high gravity early • Gas was pushed out to them • Nevertheless, they still collected dust and debris which is buried under gas Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. Jupiter as a "cosmic vacuum cleaner" http://en.wikipedia.org/wiki/Comet_Shoemaker%E2%80%93Levy_ 9 Comet Shoemaker–Levy 9 was a comet that broke apart and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of Solar System objects. The impact of SL9 highlighted Jupiter's role as a "cosmic vacuum cleaner" for the inner Solar System. The planet's strong gravitational influence leads to many small comets and asteroids colliding with the planet, and the rate of cometary impacts on Jupiter is thought to be between 2000 and 8000 times higher than the rate on Earth.[40] If Jupiter were not present, the probability of asteroid impacts with the Solar System's inner planets would be much greater. Copyright © 2010 Pearson Education, Inc. Jupiter as cosmic vacuum cleaner The extinction of the dinosaurs at the end of the Cretaceous period is believed to have been caused by the Cretaceous–Paleogene impact event which created the Chicxulub crater,[41] demonstrating that impacts are a serious threat to life on Earth. Astronomers have speculated that without Jupiter to mop up potential impactors, extinction events might have been more frequent on Earth, and complex life might not have been able to develop.[42] This is part of the argument used in the Rare Earth hypothesis. So, thank you Jupiter for protecting us!!!!! Copyright © 2010 Pearson Education, Inc. Ode to Jupiter • https://www.youtube.com/watch?v=3afEX8a2j Pg 1 min. turn up resolution • http://www.space.com/29978-nasa-juno-oneyear-jupiter.html and look at video in the article • See https://en.wikipedia.org/wiki/Juno_(spacecraft )#Planned_deorbit_and_disintegration for overview Copyright © 2010 Pearson Education, Inc. Quiz/activity 1. On full page, draw to best detail you can the structure of Jupiter, all layers. 2. Then… 3. flip the page, and use book/notes to do this again, with even better detail. Copyright © 2010 Pearson Education, Inc.