Astronomy- Ch. 7
What do we mean by hydrogen compounds? In what kinds of planets and/or small bodies are they major ingredients?
Hydrogen compounds are compounds that include water such as water (H20), methane (CH4), and ammonia (NH3). They are found in the jovian planets Jupiter, Saturn, Uranus, and Neptune.
Make sense? If Pluto were as large as the planet Mercury, we would classify it as a terrestrial planet.
If Pluto were as large as the planet Mercury, I still don't think we would classify it as a terrestrial planet- mainly because of its composition. It is made half of ice and rock-similar to a comet. Also, since it is located so far from the Sun, basically the Keiper belt, it would just be a really, really large comet.
Which terrestrial planets have had volcanic activity at some point in their histories?
Mercury has had ancient lava flows that created plains and tall, steep cliffs that are very huge; Venus also has shown past/present volcanic activity; Earth obviously; and Mars has HUGE ancient volcanoes (much larger than those on Earth). -Jupiter's moon Io, Earth's Moon, Saturn's moon enceladus
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.
Make sense? 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)
Make sense? Saturn is the only planet in the solar system with rings.
No, Jupiter, Uranus, and Neptune also have rings along with Saturn.
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 day/night, the fact that 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.
Make sense? 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.
Describe at least two "exceptions to the rules" that we find in our solar system.
2 Exceptions: -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.
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).
Which column tells you how much a planet's orbit deviates from a perfect circle? Based on that column, are there any planets for which you would expect the surface temperature to vary significantly over its orbit? Explain.
Although it's not in the table, orbital eccentricity is what tells you how much a planet's orbit deviates from a perfect circle. Mercury is the planet that would deviate in surface temperature the most during its orbit because it's orbital eccentricity is 0.2056 (for example, Earth's is only 0.0167). Then Mars is next. Venus is the most circular orbit with an eccentricity of 0.0068. Although, if we include the dwarf planets, Pluto has the greatest orbital eccentricity of 0.2488.
What are asteroids? Where do we find most asteroids in our solar system?
Asteroids are rocky bodies that orbit the Sun much like planets, but are much smaller. (the largest asteroids are dwarfed by our Moon). Only two asteroids are round: Siri and Vespa. Most are found within the asteroid belt between the orbits of Mars and Jupiter.
How do astronomers measure the following planetary properties: A. Mass B. Rotation rate C. Temperature
Astronomers measure _____ by: 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
Make sense? Comets in the Kuiper belt and Oort cloud have long, beautiful tails that we can see when we look through telescopes.
Comet tails are caused by the ice vaporizing from the iceyness of when it gets too close the the Sun. You need heat to vaporize the tails so...
What are comets? How do they differ from asteroids?
Comets are small objects that orbit the Sun as well, but they are made largely of ices (water ice, ammonia ice, and methane ice) mixed with rock. (Sometimes visible to naked eye as light with long, beautiful tails). Found in two main locations call the Kuiper belt (which includes Pluto an Eris) and the Oort cloud.
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.
Briefly describe the overall layout of the solar system.
Planets orbiting the sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Then the Keiper belt, then the Oort cloud. -tells us 4 main things: First, large bodies in the solar system have orderly motions; second, planets fall into two major categories; third, swarms of asteroids and comets populate the solar system; and lastly, several notable exceptions to these trends stand out.
Make sense? 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.
The text says that planets can be classified as either terrestrial or jovian, with Pluto fitting neither category. 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).
What are the basic differences between the terrestrial and jovian planets? Which planets fall into each group?
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. T= Mercury, Venus, Earth, Mars; J= Jupiter, Saturn, Uranus, Neptune
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.
What is the most abundant element in the Solar System? What is the second most abundant?
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.
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).
Make sense? 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).
What would the solar system look like to your naked eye if you could view it from beyond the orbit of Neptune?
To naked eye, you wouldn't see much because the next closest thing (Uranus) would be so, so far away.
Make sense? 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. Happens b/c of the greenhouse effect (CO2- 96% of it's atmosphere)
What are the four major features of our solar system that provide clues to how it formed? Describe each one briefly.
a. Patterns of motion among large bodies- Sun, planets, large moons rotate in an organized way- (co-planar) b. Two major types of planets- terrestrial vs. jovian planets c. Asteroids and comets- locations, orbits, and compositions follow distinct patterns d. Exceptions to the rules- Earth is inner planet with large moon, Uranus is only side tilted axis, etc.
