Astronomy - Module 5
Q5.25 From the video "Crash Course: Saturn," describe the two possible theories for the origin of Saturn's rings.
An icy moon faced a huge collision that broke the moon up into particles that formed around Saturn, colliding with each other to deform a flattened ring. Or, there could have been a large moon near Saturn that had rocky bits near the core and ice near the surface. As it went through the material during Saturn's formation, the icy layer got stripped off and collisions created a flat disk around Saturn.
Q5.21* From the "Interstellar Interlopers" article, describe three differences between the 2nd interstellar object (2I/Borisov) and Oumuamua that indicate Borisov is more like the kind of object we expected to find.
Borisov has a halo/tail, has a steady light curve, and has water ice pieces that broke off when it went by the sun while Oumuamua didn't.
Q5.29 From the video "Kingdom of Saturn," explain what Cassini discovered about the zodiacal light that can be seen on very dark nights.
Cassini explained it as the reflection of sunlight off of dust in the plane of the solar system.
Q5.38 From the video "The Bizarre Characteristics of Titan," describe what is thought to be the main process that keep Titan's surface fairly "new" looking, less than 100 million years old.
Cryovolcano's are believed to contribute to this as they mimic the activity of volcanoes on Earth, by drawing material from inside the planet to freeze over the surface and renew it.
Q5.60 From lecture, explain what causes the difference in color between the light-colored orange/red hues of Jupiter and Saturn vs the darker colors of blue and green in the atmospheres of Uranus and Neptune.
Differences in gas composition is what causes this differentiation of colors between the planets. Saturn and Jupiter's atmosphere are red/orange because of NH3, while Neptune and Uranus are blue because of methane and absence of NH3 because temps reach their freezing point.
Q5.41* From the video "Asteroids," from the Arizona site and the Sudbury site, the video discusses 3 additional features, aside from those in the previous question, that are common indicators of impact sites. Describe each of these three, and briefly explain how the impact process results in each feature.
Diffused sandstone: a crystal matrix formation resulting from being melted due to the release of high energy shockwaves like an impact. Shatter cones: a cone like structure formed due to shockwaves interacting with target rocks. Iridium abundance: One of the rarest metals on Earth, but abundant in space.
Q5.10 From your textbook's chapter 12.5, describe how it was discovered that Uranus has a ring system long before the Voyager spacecraft was able to capture an image of the rings during its flyby?
During the 1977 occultation, as Uranus passed over a star, it briefly dimmed several times before Uranus reached it, which allowed astronomers to count and map the rings.
Q5.30* From the video "Kingdom of Saturn," name and explain three observed properties of Saturn's moon Enceladus that led us to believe there is liquid water in the interior near the South Pole of the moon.
Enceladus has been detected to spray out jets of water vapor and water ice from large geysers in the surface. It was predicted that there is a large subsurface ocean, that sloshes around and causes carbon dioxide to make it fizzy. Cassini has also detected tiny silicate particles that can only form in boiling water. Additionally, it has a magnetic signature similar to that of water, and has been resurfaced which keeps the surface smooth.
Q5.6* From your textbook's chapter 12.2, why aren't all four of Jupiter's major moons composed primarily of ice, given that ice was by far the most abundant solid substance in the outer solar system?
Europa and Io are mostly rocky, possibly because of their close proximity with Jupiter. Jupiter gives off enough radiation to heat the moons and vaporize any ice near Jupiter.
Q5.58 From lecture, explain how, in 1859, Scottish mathematician James Maxwell deduced from observational evidence that Saturn's rings were not solid but instead composed of many smaller granules.
He measured the Doppler shift of Saturn's rings and discovered that its circular velocity is not that of a solid object, but rather mimics Jupiter's moons.
Q5.50* From lecture, explain why Iridium is more common in the interior of the Earth than in the surface rocks and crust of the Earth.
Heavy, dense metals sunk down to the core of the Earth when the Earth was heated, including Iridium. An impact 65 million years ago (killed off dinosaurs) is what distributed Iridium around the surface. Volcanoes don't go deep enough to distribute Iridium.
Q5.37 From the video "The Bizarre Characteristics of Titan," (a) describe the process that we believe gives Titan its hazy orange color, and on a related note (b) describe what replenishes the methane in Titan's atmosphere (discussed also in the "Kingdom of Saturn" video at around the 30:20 mark).
Hydrocarbons in its atmosphere give it an orangey look. Cryovolcano's replenish the methane in the atmosphere.
Q5.12 From your textbook's chapter 13.1, (a) explain how we determined that the asteroid Psyche is made largely of metal. Also, (b) explain how it is possible for an asteroid to be made primarily from metal instead of a mix of metal, rock and ice?
It appears bright when a radar beam is aimed at it because metal is a better reflector of radar than stone. It is suspected that metal asteroids came from a body whose interior differentiated, with heavy metals sinking to the center.
Q5.44 From the video "Asteroids," explain what was significant about the Murchison meteorite that fell in Australia in the 1960's.
It had traces of organic compounds known as amino acids, which are essential to all life.
Q5.47 From the NASA video about Oumuamua, why do we think Oumuamua is likely some kind of comet?
It has a large orbit, and a nongravitational acceleration (change in orbit), and came from afar.
Q5.34 From the video "The Bizarre Characteristics of Titan," explain two observations by the spacecraft Cassini that indicate Titan has a layer of liquid water in its mantle.
It has low frequency radio waves, which indicates a magnetic signature similar to that of water. (Water is a good reflector of lower frequency waves). The surface has shifted, which could imply that it is floating on a liquid layer.
Q5.35* From the video "The Bizarre Characteristics of Titan," explain what is thought to be the cause of Titan's orbital eccentricity and tilted orbital plane.
It is thought to have experienced large collisions with Saturn's moons in the past, and due to its large distance from its planet, it contains more energy, making it more elliptical.
Q5.33 From the video "Kingdom of Saturn," explain what scientists decided to crash the Cassini spacecraft into Saturn instead of leaving it in a relatively stable orbit around Saturn.
It ran out of fuel and scientists didn't want to contaminate any of Saturn's moons with microbes that might have found their way in during assembly.
Q5.52 From lecture, explain why Astronomers thought that Jupiter's innermost large moon, Io, would be cold and lifeless, with little geological activity like Earth's Moon, prior to the images taken by the Voyager I spacecraft.
It was believed to be too small to retain its own heat, and because of our observance of our own moons, we believed them to be similar.
Q5.20 From the "Interstellar Interlopers" article, explain how we know that Oumuamua has a very elongated shape (10:1 ratio, approximately).
Its light curve shows that it is tumbling due to its consistent light curve factor of 10.
Q5.19 From the "Interstellar Interlopers" article, explain why it was surprising that Oumuamua did not seem to have a coma or a tail like a comet.
Its orbit is similar to that of a comet, but it doesn't have a tail or any other characteristics similar to that of a comet. Something must be pushing on it, changing its orbit.
Q5.24 From the video "Crash Course: Jupiter," explain the source of Jupiter's thin ring system.
Its small ring comes from meteorite impacts with its moon, which creates the small ring made up of dust.
Q5.23* From the video "Crash Course: Jupiter," explain the two different theories we currently have about how Jupiter formed (and what kind of core it has).
Jupiter began the same as other planets, with collisions creating a rocky metallic core that eventually drew in more gas until it became what it is today. The other theory is that the flat disk of gas and dust that created the universe collapsed in several places that formed clumps that collided and created Jupiter. This assumes that Jupiter has no core.
Q5.51* From lecture, explain what are the Kirkwood gaps and how they are formed. As part of your answer, explain why an asteroid in one of the gaps would be affected so radically while an asteroid just to one side or the other of the gap isn't affected.
Jupiter exerts a greater force in certain areas due to resonance. An asteroid on either side of the gap isn't affected like an asteroid in the gap because resonance is specific to certain orbits.
Q5.18 From the article and embedded video about Juno and zodiacal light, (a) explain why the zodiacal dust further away from the Sun than about 2 Astronomical Units, and (b) explain why astronomers think Mars may be responsible for most of this dust.
Jupiter's gravity prevents dust from going past it to the more outer solar system. This dust is travelling in a nearly circular orbit around the sun, and the only culprit in between Earth and Jupiter is Mars.
Q5.4* From your textbook's chapter 11.3, explain what causes the color difference between the light and dark bands in the atmosphere of Jupiter.
Lighter bands are areas with lower pressure, while darker bands are areas with higher pressure. They are permanent bands of high and low pressure. The internal heat of Jupiter contributes to these convection currents of its atmosphere.
Q5.27 From the video "Crash Course: Saturn," describe what causes the long, winding channels and apparent lakes on the surface of Saturn's moon, Titan.
Liquid methane is what the lakes are composed of, and are what create the channels.
Q5.48 From the NASA video about Oumuamua, did our observations verify that Oumuamua behaves like ordinary comets in our solar system? Explain why or why not.
No, because its course has not changed and it has no gas cloud or tail.
Q5.13* From your textbook's chapter 13.2, we learn that discoveries small asteroids that may be hazards to the Earth is very difficult, so it is important to know as we find them, how many more are still left to be discovered. Describe two ways in which we know that our surveys to date have found roughly 90% of these hazardous asteroids larger than 1 kilometer in size.
One way is to analyze and count the craters on lunar maria, since they are directly correlated with the amount of asteroids and comets on earth-crossing orbits. Or, we can see how often the surveys rediscover an asteroid, completing our inventory of asteroids.
Q5.26 From the video "Crash Course: Saturn," explain how Saturn's moon Mimas is responsible for the Cassini Division in Saturn's rings.
Particles in the Cassini Division orbit Saturn twice for every one time Mimas orbits. Because of this, Mimas yanks these particles out of their orbit. This is known as resonance.
Q5.8 From your textbook's chapter 12.4, we revisit the topic of why Pluto is not considered to be a planet. Briefly summarize the author's reasoning, explaining why Pluto's status was demoted to dwarf planet recently by astronomers.
Pluto's orbit and small size is different from other planets in the solar system. Additionally, with the discovery of Eris and other TNO's, it became clear that Pluto was not unique from the other TNO's and was classified as a dwarf planet instead.
Q5.54 From lecture, explain what provides the energy to keep Io's orbit elliptical (higher energy orbit) instead of circular (lower energy orbit).
Resonance with other moons.
Q5.55 From lecture, (a) explain what is the Roche limit, and (b) explain why the debris that makes up Saturn's ring system doesn't coalesce to form a moon.
Roche limit is the closest distance a body can get to a planet before it tears apart due to tidal forces. Saturn's rings made of debris that is too close to Saturn to be a moon; they're in the Roche Limit. Tides stronger than self-gravity.
Q5.3* From your textbook's chapter 11.2, how do we know Saturn has an additional internal heat source not found on Jupiter?
Saturn in expected to have much less primordial heat, unlike Jupiter which is expected to have a lot. However, Saturn does has much more primordial heat than Jupiter. This means Saturn must have another heat source that is unlike Jupiter's.
Q5.57 From lecture, (a) explain what is the additional heat source that exists in Saturn that doesn't exist in Jupiter, then (b) explain what evidence in Saturn's atmosphere reveals that this heat source is operating in the way we describe.
Saturn's atmosphere is cold enough for Helium to condense into solid droplets that sink into the interior, which transforms into heat as it sinks due to gravity. Helium is more depleted in Saturn's atmosphere compared to Jupiter.
Q5.32 From the video "Kingdom of Saturn," explain what Saturn's shepherd moons are and what role they play with respect to Saturn's rings.
Shepherd moons are small moons that sweep clear their lane of travel and create small gaps in Saturn's rings. They keep particles within a ring contained due to their gravity.
Q5.46 From the video on observing meteor showers, why is the best time to view meteorites after midnight rather than before midnight even though the sky is equally dark during both times?
The Earth has rotated to where our perspective changed to be in the direction of the dust stream.
Q5.15 From your textbook's chapter 13.4, describe the Kuiper Belt and the Oort Cloud.
The Kuiper belt is a large space beyond Neptune where many TNOs and comets can be found. The Oort cloud is a reservoir of icy objects from which comets are derived.
Q5.11 From your textbook's chapter 13.1, (a) describe what two properties asteroid family members share, and (b) explain how asteroid families originate
The asteroids in a family share a similar composition as well as the same orbit. Families could have originated from the breakup of a larger body or the collision of two asteroids.
Q5.40 From the video "Asteroids," briefly describe three reasons why geologist Daniel Barringer concluded that the crater was an impact crater rather than a volcanic crater.
The composition of the material around the crater was almost pure iron. Pulverized rock was spread around the crater, into a fine powder. A bed of rocks nearby was overturned.
Q5.39 From the video "Asteroids," explain two reasons why Grove Gilbert initially concluded that the large meteor crater in Arizona (now known as Barringer crater) was caused by volcanism as opposed to an impact.
The crater found was associated with volcanic peaks. Additionally, due to its proximity and similarities with another crater in the area that was the result of an underground steam explosion, Gilbert believed that they both were.
Q5.17 From the article and embedded video about Juno and zodiacal light, explain how the Juno spacecraft detected the interplanetary dust that exists in the inner solar system, the source of the zodiacal light.
The dust was detected on the camera on Juno, which displayed streaks of something appearing then disappearing. This allowed scientists to measure the distribution of the dust. Juno's solar panels also experienced many small impacts, which were this debris.
Q5.14 From your textbook's chapter 13.3, explain what causes the difference in behavior between the gas tail and the dust tail of comets.
The gas tail is made up of ionized gas, which is carried outward (created) by streams of ions that the sun emits. The dust tail is made up of small dust particles.
Q5.42 From the video "Asteroids," explain how the large asteroid impact in the past shaped the Sudbury landscape in order to make it a profitable mining center.
The initial cavity collapsed onto itself due to gravity. The crater filled with a lake of hot liquid rock, that differentiated as it cooled. The metals were concentrated at the bottom of the crater, creating the mining deposits of Sudbury.
Q5.2 From your textbook's chapter 11.2, briefly describe two internal heat sources that operate on Jupiter that make the whole planet a little bit warmer than we might expect just based on the amount of sunlight it absorbs.
The original heat from Jupiter's formation could still be inside it and Jupiter could have slowly concentrated heat after forming.
Q5.9 From your textbook's chapter 12.5, explain why astronomers suspected that Saturn's moon Enceladus was somehow releasing water/ice into space, even before the famous pictures taken by Cassini showed the geysers in operation on the surface of the moon.
The particles in Saturn's E Ring are very small and composed of water ice, which tends to dissipate. However, because of the E Ring's ongoing existence, astronomers could assume that something was replenishing it - Enceladus. This meant that Enceladus was shooting water into space.
Q5.16* From your textbook's chapter 14.1, (a) what is the radiant of a meteor shower? (b) What causes the radiant effect that makes meteor trails all seem like they originate from (or point back towards) a specific place on the sky?
The radiant is the spot in the sky that meteor streams seem to diverge from in a meteor shower. The dust and particles that produce meteor showers seem to come from one spot when they encounter earth due to a perspective effect that occurs due to Earth's orbit.
Q5.59* From lecture, explain the four lines of evidence that indicate some kind of catastrophic event in the Saturn system about 100 million years ago.
The ring system is only about 100 mil years old. Titans surface age is approx. 100 mil years old, around the same time the rings were formed. Titan's mass and energetic orbit suggest a large collision in the past. Saturn's rings are mostly ice, very little dust. Rings get darker from dust after 100 million years.
Q5.56 From lecture, how do we know that Saturn hasn't always had a ring system?
The ring system is unstable, objects collide all the time and fall into Saturn. The ring is slowly decaying.
Q5.1 From your textbook's chapter 11.2, the gas in the atmospheric bands of Jupiter moves at different speeds, depending on latitude, and Jupiter has no solid surface to view. How have we been able to determine the true rotation period to this planet?
The rotation of Jupiter's mantle and core can be determined by the periodic variations in the radio waves it gives off, which are controlled by its magnetic field.
Q5.28* From the video "Crash Course: Saturn," explain what properites of the lakes on the surface of Titan make us think there is active weather in the atmosphere of Saturn's moon Titan.
The shorelines of the methane lakes appear to change over time, hinting that Titan has weather driven by methane.
Q5.5 From your textbook's chapter 12.2, explain how we know that Jupiter's outermost moon, Callisto, is composed mostly of ice in its interior, even though we can only see the surface.
The survival of impact craters on the surface tells us that an icy object on the surface can retain them. Additionally, we can tell that the interior is dense because of the gravitational pull on the Galileo spacecraft.
Q5.49* From lecture, normally, when a comet's orbit is different than we expect, it is because of something like the Yarkovsky Effect mentioned in question 6.19. Explain two reasons why we do not believe cometary jets are the cause of Oumuamua's peculiar path through the solar system.
There is no physical evidence of that occurring, such as a tail or jet. Additionally, nothing is changing its rotation like a jet.
Q5.43 From the video "Asteroids," in the Sheridan Cave, describe the evidence that indicates the disappearance of the mega-mammals and Clovis people was caused by an impact.
There was an increased of magnetism detected, which is caused by the iron. Due to this presence of iron with organic material, it makes sense that a large catastrophic event such as an impact had to have eliminated life.
Q5.31 From the video "Kingdom of Saturn," (a) describe the mechanism that scientists believe is causing the subsurface water to be jetted out into space through the fissures, and (b) what happens to the water that escapes from Enceladus' weak gravity?
They believe that carbon dioxide is making the liquid water fizzy, causing it to spray out of the geysers. Most of the water particles fall back onto Enceladus as snow, repairing the surface. The water that escapes Enceladus' weak gravity creates a ring around Saturn called the E Ring.
Q5.45 From the video on observing meteor showers, why does the video advise against the use of telescopes or binoculars?
They restrict your field of view.
Q5.53 From lecture, explain the source of heating that keeps Jupiter's Moon Io so volcanically active.
Tidal heating from Jupiter heats Io's core/interior. Resonance also keeps energy in Io.
Q5.36 From the video "The Bizarre Characteristics of Titan," describe two reasons why the atmosphere of Titan is so much thicker (extending further from the surface) compared to the atmosphere of the Earth.
Titan's gravity is weaker than Earth's, making it harder to constrict it closer to the surface of the planet. Additionally, Titan is much smaller than Earth but its atmosphere is much bigger than Earth's.
Q5.22 From the video "Crash Course: Jupiter," explain how belts and zones form in the atmosphere of Jupiter.
Upwelling air cools and forms white ammonia clouds, creating Jupiter's zones. The air sinks and the chemistry in them changes, creating yellow/red/brown belts.
Q5.7 From your textbook's chapter 12.2, describe two lines of evidence that indicate the presence of an ocean of liquid water beneath Europa's icy crust.
When the layer of ice on Europa's crust breaks and creates cracks, water seeps through the cracks from underneath and makes the ridges observed on Europa's surface. Additionally, the "magnetic signature" of Europa is that of a liquid water ocean, not one of ice or rock.
