Chapter 7
10. What are the four major features of our solar system that provide clues to how it formed? Describe each one briefly.
-Large bodies in the solar system have an orderly motion -Planets fall into two major categories -Swarms of asteroids and comets populate the solar system -Several notable exceptions to these trends
15. What is the difference between a planet, a dwarf planet and most asteroids and Kuiper Belt Objects?
A planet is large and orbits the sun. Dwarf planets include Pluto and Eris, which don't count as planets because of their lack of identifiable characteristics of either Terrestrial or Jovian planets. Asteroids, although they orbit the sun are much, much smaller than planets. And Kupier Belt objects (which include Pluto and Eris) are past the Jovian planets and are basically large iceballs (large comets).
13. What are asteroids? Where do we find most asteroids in our solar system?
Asteroids are rocky bodies that orbit the Sun and are found within the asteroid belt.
14. What are comets? How do they differ from asteroids?
Comets are also small objects that Orbit the Sun but they are made largely of ices (such as water ice, ammonia ice and methane ice) mixed with rock. In the Kuiper Belt and Oort cloud
12. What do we mean by hydrogen compounds? In what kinds of planets and/or small bodies are they major ingredients?
Compounds containing hydrogen, such as water (H2O), ammonia (NH3) and methane (CH4). They are found in the Jovian (gas giants) planets
19. Comets in the Kuiper belt and Oort cloud have long, beautiful tails that we can see when we look through telescopes.
False, those are only the comets that rarely enter into the inner solar system.
24. Saturn is the only planet in the solar system with rings.
No, Jupiter, Uranus, and Neptune also have rings along with Saturn.
1. What would the solar system look like to your naked eye if you could view it from beyond the orbit of Neptune?
It would not look like much. The Sun and planets are all quite small compared to the distances between them. They would only be pinpoints of light, and even the Sun would be just a small bright dot in the sky.
7. Which planet has the shortest days? Do you see any notable differences in the length of a day for the different types of planets? Explain.
Jupiter has the shortest days because its rotational period is 9.93 hours (in relation, ours is 23.93 hours). In general, the terrestrial planets have longer (some very long) rotation period (days) than the jovian periods (hours). the Longest day is Venus which has a rotational period of 243 days.
8. Which planets should not have seasons? Why?
Mercury should not have seasons at all and Jupiter should hardly- because the axis tilt is very low. (M=0.0 degrees and J=3.1 degrees). Venus doesn't have seasons really because its axis tilt is 180 degrees which is still perpendicular, but just spins the opposite direction. Uranus would have the biggest seasons.
23. Moons cannot have atmospheres, active volcanoes, or liquid water.
Moons can have atmospheres and active volcanoes. For example, Saturn's moon Enceladus has ice fountains spraying out and Titan has a thick atmosphere. Another example is that Jupiter's moon Io has active volcanoes (actually the most volcanically active body in the entire solar system-reason being that Jupiter's "tidal forces" greatly affect Io due to how close they are to each other)
4. Notice the relationship between distance from the Sun and surface temperature. Describe the trend, explain why it exists, and explain any notable exceptions to the trend.
Obviously, planets that are farther away from the Sun will be cooler than those much closer in orbit. The exceptions include that mercury has two very different surface temperatures based on drastic differences in day/night temperatures due to its unusual pattern of 57 day long rotation rates. Venus is 40K hotter than Mercury is (b/c of it's atmosphere). Also, the temperature of Uranus and Neptune is the same despite being much farther away.
20. Our Moon is about the same size as moons of the other terrestrial planets.
Our Moon is very large in comparison to the Earth. It is roughly ¼ as large in diameter (but 1/80th the mass). However, it is only large in comparison to it's planet. It is not the largest Moon in the solar system. ***But it is definitely the largest of the terrestrial planets moons b/c Mercury and Venus have no moons at all and Mars' two moons (Phobos and Deimos) are very small.
18. Pluto orbits the Sun in the opposite direction of all the other planets.
Pluto does not orbit the Sun in the opposite direction of all the other planets. When the forces collided into each other, the planets all began to form in the same circular(ish) orbit. It's orbit is more elliptical and comes closer to Neptune and is more parahelion. (The orbits do NOT intersect and never will.)Pluto orbits the Sun in the opposite direction of all the other planets.
11. What are the basic differences between the terrestrial and jovian planets? Which planets fall into each group?
Terrestrial - four planets of the inner solar system: Mercury Venus Earth and Mars They are small, dense with rocky surfaces and an abundance of metals in their cores. They also have few moons, if any and no rings. closer to the Sun Jovian - Four large planets of the outer solar system: Jupiter, Saturn, Uranus and Neptune They are much larger in size and average density than the terrestrial planets. They have rings and numerous moons. they are made mostly of hydrogen, helium hydrogen compounds
5. The text says that planets can be classified as either terrestrial or jovian. Describe in general how the columns for density, composition, and distance from the Sun support this classification.
Terrestrial Planets are small in mass and size, close to the Sun, made of metal and rock, and have few moons and no rings. Jovian planets have large mass and size, far from the Sun, made of H, He, and hydrogen compounds, and rings and many moons. Pluto does not fit either because of its distance from the sun and its composition. It is far from the sun, but made of ices, rock; therefore, neither terrestrial nor jovian apply to Pluto. It's density is also in between what both types of planets should be (with terrestrial having high densities 3.93-5.43 and jovian being .70-1.64).
16. What is the Kuiper belt? What is the Oort cloud? How do the orbits of comets differ in the two regions?
The Kuiper belt is a donut-shaped region beyond the orbit of Neptune (at 50 AUs away). It contains at least 100,000 icy objects (including the largest two Pluto and Eris). These objects orbit the Sun in the same direction as the planets, but have a large inclination to the ecliptic plane. The Oort cloud is the second cometary region, much, much farther from the Sun (50,000 AUs-100,000 maybe 150,000 AUs- aka a quarter of the way to the next star). Comets of the Oort cloud theoretically have randomly inclined orbits which give the Oort cloud a roughly spherical shape.
3. What is the most abundant element in the Solar System? What is the second most abundant? Why
The most abundant element in the Solar System is hydrogen (about 75%), next is helium (about 25%). Oxygen is third. Then, neon, nitrogen, carbon, silicon, magnesium, iron, and sulfur.
6. Describe the trend you see in orbital periods of planets around the sun and explain the trend in terms of Kepler's third law.
The orbital period of the planets gets significantly longer depending on the planet's distance from the Sun. Kepler's third law explained this by saying that things that are farther away from the Sun move much, much slower (and also they move slower when in farther away parts of their orbit). The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.
22. The weather conditions on Mars today are much different than they were in the distant past.
The weather conditions on Mars today are indeed much different than they were in the distant past. We know this because although Mars is frozen today, dried-up riverbeds, rock-strewn floodplains, and minerals formed in water offer clear evidence that Mars used to be wet and warm (ceasing on the surface about 3 billion years ago).
17. Describe at least two "exceptions to the rules" that we find in our solar system.
Uranus rotates nearly on it's side and Venus rotates backwards. Also, while the terrestrial planets have no moons or very small moons, ours is the largest Moon in the solar system. -Earth has one of the largest moons in the solar system, despite the fact that it is a terrestrial planet (which usually have either no moons or very tiny ones). -While most planets rotate in the same direction they orbit, Uranus rotates nearly on its side and Venus rotates "backward" (clockwise rather than counter-clockwise). -basically, motion likes to be prograde. Neptune's moon Triton also goes around backwards.
21. On average, Venus is the hottest planet in the solar system-even hotter than Mercury.
Venus is the hottest planet in the solar system at 740K on average- even surpassing the temperature of the closest planet Mercury which is 700K or 100K depending on day or night.
2. How do astronomers measure the following planetary properties: A. Mass B. Rotation rate C. Temperature
a. Mass: using gravity and the orbital period of something orbiting around the object you're looking for the mass of. The heavier the planet, the stronger it attracts the moon and faster the moon moves around it. Over a long period of time, you measure the angular distance of the moon to the planet, timing the motion. Using Kepler's third law formula to find the object's mass. b. Rotation rate: They usually have a dark spot (especially the jovian planets) that can be used to measure how long it takes for the dark spot to show back around.The next strategy for planets like Jupiter (that don't have any identifiers) would be to land a rocket with a radio signal on it. (Ex. You can't measure Jupiter's rotation rate really though b/c it goes around at different spots at different speeds (because it is gaseous). c. Temperature: For stars, it is using the color. For planets, it is using the radiated heat- which works by using the wavelength spectrum of Planck's Law
