Week 09 The Solar System

We now know that an extreme ____ ____ bakes Venus's surface to an incredible 470°C (about 880°F), trapping heat so effectively that nighttime offers no relief. Day and night, Venus is hotter than ___ ___ ___, and the thick atmosphere bears down on the surface with a pressure equivalent to that nearly a kilometer (0.6 mile) beneath the ocean's surface on Earth. Far from being a beautiful sister planet to Earth, Venus resembles a traditional view of hell

greenhouse effect, a pizza oven

Uranus lies ____ ____ ____ from the Sun as Saturn. Uranus (normally pronounced YUR-uh-nus) is much smaller than either Jupiter or Saturn but much larger than Earth. It is made largely of hydrogen, helium, and hydrogen compounds such as water (H2O), ammonia (NH3), and methane (CH4). Methane gas gives Uranus its pale blue-green color (Figure 6.9). Like the other giants of the outer solar system, Uranus lacks a ____ ____. More than two dozen moons orbit Uranus, along with a set of ____ somewhat similar to those of Saturn but much darker and more difficult to see. The entire Uranus system—planet, rings, and moon orbits—is ____ ____ ____ ____ compared to the rest of the planets.

twice as far, solid surface, rings, tipped on its side

To reach the orbit of Jupiter from Mars, we must traverse a distance that is more than double the total distance from the Sun to Mars, passing through the asteroid belt along the way. Upon our arrival, we find a planet much larger than any we have seen so far (Figure 6.7). Jupiter is so different from the planets of the inner solar system that we must adopt an entirely new mental image of the term planet. Its mass is more than 300 times that of Earth, and its volume is more than ____ times that of Earth. Its most famous feature—a long-lived storm called the ____ ____ ____ —is itself large enough to swallow two or three Earths. Like the Sun, Jupiter is made primarily of hydrogen and helium and has ____ ____ ____. If we plunged deep into Jupiter, the increasing gas pressure would crush us long before we ever reached its core. Jupiter reigns over dozens of moons and a thin set of ____ (too faint to be seen in most photographs). Most of the moons are very small, but four are large enough that we'd call them planets or dwarf planets if they orbited the Sun independently. These four moons—Io, Europa, Ganymede, and Callisto—are often called the ____ ____ (because Galileo discovered them), and they display varied and interesting geology. Io is the most volcanically active world in the solar system. Europa has an icy crust that may hide a subsurface ocean of liquid water, making it a promising place to search for life. Ganymede and Callisto may also have subsurface oceans, and their surfaces have many features that remain mysterious.

1000, The Great Red Spot, no solid surface, rings, Galilean Moons

The ____ planets (terrestrial means "____ -____") are the four planets of the inner solar system: Mercury, Venus, Earth, and Mars. These planets are relatively ____ and dense, with rocky surfaces and an abundance of metals in their cores. They have few moons, if any, and no ____ ... The ____ planets (jovian means "____ -____") are the four large planets of the outer solar system: Jupiter, Saturn, Uranus, and Neptune. The jovian planets are much ____ in size and lower in average density than the terrestrial planets, and they have ____ and many moons. They lack ____ ____ and are made mostly of hydrogen, helium, and hydrogen compounds- compounds containing hydrogen, such as water (H2O), ammonia (NH3), and methane (CH4 ).

Terrestrial, Earth like, small rings, Jovian, larger, rings, solid surfaces

Neptune looks nearly like a twin of Uranus, although it is more strikingly ____ ... Neptune has ____ and numerous moons. Its largest moon, Triton, is larger than Pluto and is one of the most fascinating moons in the solar system. Triton's icy surface has features that appear to be somewhat like geysers, although they spew nitrogen gas rather than water into the sky. Even more surprisingly, Triton is the only large moon in the solar system that orbits its planet "____." Extra Credit for students who start working on these questions early: Timeanddate.com gives a list of "Planets Visible in the Night Sky in Philadelphia, Pennsylvania, USA." Send me an email before midnight Sunday, March 27, with the subject heading "Give me a point!" and listing the planets visible tonight and the times of visibility, and I'll add 1 point to your 5-point Reading Notes Questions grade.

blue, rings, backward

We conclude our tour at Pluto (Figure 6.11), which reigned for some 75 years as the "ninth planet" in our solar system. However, the 2005 discovery of the slightly more massive Eris, and the fact that dozens of other objects are not much smaller than Pluto and Eris, led scientists to reconsider the definition of "planet." The result was that we now consider Pluto and Eris to be ____ ____, too small to qualify as official planets but large enough to be round in shape... Pluto and Eris belong to a vast collection of icy objects that orbit the Sun beyond Neptune, making up what we call the ____ ____.

dwarf planets, Kuiper Belt

The next planet on our tour is Mars, the last of the four inner planets of our solar system (Figure 6.6). Mars is larger than Mercury and the Moon but only about ____ Earth's size in diameter; its mass is about 10% that of Earth. Mars has ____ ____ ____, Phobos and Deimos which may once have been asteroids that were captured into Martian orbit early in the solar system's history. .. Although Mars is frozen today, the presence of dried-up riverbeds, rock-strewn floodplains, and minerals that form in water offers clear evidence that Mars had at least some warm and wet periods in the past. Major flows of ____ ____ probably ceased at least 3 billion years ago, but some liquid water could persist ____, perhaps flowing to the surface on occasion.

half, two tiny moons, liquid water, underground

The journey from Jupiter to Saturn is a long one: Saturn orbits nearly twice as far from the Sun as Jupiter. Saturn, the ____ -____ planet in our solar system, is only slightly smaller than Jupiter in diameter, but its lower density makes it considerably less massive (about one-third of Jupiter's mass). Like Jupiter, Saturn is made mostly of hydrogen and helium and has ____ ____ ____. Saturn is famous for its spectacular ____. All four of the giant outer planets have rings, but only Saturn's can be seen easily... Saturn also has numerous moons, including at least two that are geologically active today: Enceladus, which has ice fountains spraying out from its southern hemi sphere, and Titan, the only moon in the solar system with a thick ____.

second largest, no solid surface, rings, atmosphere

Asteroids are rocky bodies that orbit the Sun much like planets, but they are much ____. Even the largest asteroids are much smaller than our Moon. Most known asteroids are found within the ____ ____ between the orbits of ____ and ____. Comets are also small objects that ____ ____ ____, but they are made largely of ices (such as water ice, ammonia ice, and methane ice) mixed with rock. You are probably familiar with the occasional appearance of comets in the inner solar system, where they may become visible to the naked eye with long, beautiful ____.

smaller, asteroid belt, mars, Jupiter, orbit the sun, tails

Mercury is the innermost planet of our solar system, and the ____ of the eight official planets. It is a desolate, cratered world with no active volcanoes, no wind, no rain, and no life. Because there is virtually no air to scatter sunlight or color the sky, you could see stars even in the daytime if you stood on Mercury with your back toward the Sun. You might expect Mercury to be very ____ because of its closeness to the Sun, but in fact it is a world of both ____ and ____ extremes.

smallest, hot, hot, cold