Uranus & Neptune – ice giants; Atmosphere: H, He, and traces of methane, ‣ Methane absorbs red light, giving planets their bluish colors, ‣ Mantles: water, ammonia, and methane “ices”, ‣ Superheated (2,500 - 5,000º C) and high pressure, ‣ Cores: rock and ices. What are jovian planets like? ‣ Thick hydrogen, helium atmospheres, ‣ Layered interiors with very high pressure and cores made of rock, metals, and hydrogen compounds ‣ Very high pressure in Jupiter and Saturn can produce metallic hydrogen, ‣ All have strong storms and winds, ‣ What kinds of moons orbit jovian planets? ‣ Moons of many sizes, ‣ Many major moons show signs of geological activity, ‣ Tidal heating drives activity, ‣ Titan is the only moon with a thick atmosphere, What are Saturn’s rings like? ‣ Made up of countless individual ice particles, ‣ Extremely thin with many gaps, ‣ How do other jovian ring systems compare to Saturn’s? ‣ Much fainter ring systems with smaller, darker, less numerous particles , ‣ Why do the jovian planets have rings? ‣ Ring particles are probably debris from moons. ‣ A comet has three basic parts: ‣ Nucleus - the dark dirty snowball composed of ices and dirty dust, ‣ Coma - cloud of gas and dust surrounding the nucleus, ‣ Tail - in this case, both the dust and ion tail. Nucleus: Mostly water ice, some solid dust; “dirty snowballs” Coma: When a comet nears the Sun, its ices start to vaporize; jets of dust and gas erupt from its surface Produces a cloud around the nucleus called the coma. Tails: Gas tail - atoms of gases from the comet; Dust tail: smokesized particles (smaller than household dust) A comet’s tail always points away from the Sun! Meteoroid: ‣ A bit of interplanetary debris that falls through Earth’s atmosphere ‣ Meteor: ‣ A streak of light caused by a meteoroid, ‣ Commonly called a “shooting star” ‣ Meteorite: ‣ A space rock on the ground Types of meteorites: ‣ Stonys, ‣ 94% of meteorite falls, ‣ Rocky composition; ‣ Irons, ‣ 5% of meteorite falls, ‣ Iron-nickel alloy; ‣ Stony-Irons, ‣ 1% of meteorite falls ‣ Mixtures of iron-nickel alloy and rocky material ‣ Sun’s energy output = 3.8 x 10^26 Watts Fission: Big atomic nucleus splits into smaller pieces (like in nuclear power plants); Fusion: Small atomic nuclei combine to make a bigger one (Sun, stars) The Sun: ‣ The Sun’s size, composition, and temperature, ‣ The Sun generates energy through hydrogen fusion in the core, ‣ That energy first moves through the radiative zone of the Sun as light, ‣ Then it warms the gas in the convective zone of the Sun and that hot, gas bubbles up to the photosphere, producing granules; ‣ Thermal Radiation, ‣ Hot objects naturally give off light, ‣ The color of that light depends on the temperature of the object, ‣ The Sun and other stars light comes from this thermal radiation;
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