Midterm possible questions

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School

Western University *

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Course

1086

Subject

Astronomy

Date

Dec 6, 2023

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pdf

Pages

45

Uploaded by GeneralIceAnteater40

Quizlet: Where in our solar systems do many asteroids reside? - Most asteroids reside in the gap between Jupiter and Mars - also named the Asteroid belt or main asteroid belt. Why is there an asteroid belt? How did it form? - Orbital resonances with Jupiter prevented planetesimals between Jupiter and Mars from forming a planet. Therefore, all the planetesimals that could form a planet are trapped in this gap due to Jupiter's strong gravity Are all meteorites from the asteroid belt? - Not all meteorites are from the asteroid belt. Some such as atens, amors, and Apollo asteroids are really close to the Earth and Mars, which is out of the asteroid belt. DeJniKons: Asteroid, meteoroid, meteor, Jreball, meteorite - Asteroid: A natural rocky object in space measuring over 100 m in diameter - Meteoroid: A natural rocky object in space measuring less than 100 m in diameter - Meteor: A small streak of light associated with the entering of a small meteoroid entering the sky - the light is a result of the burning caused by the fricKon between the object and atmosphere - Fireball: A large streak of life associated with the entering of a large asteroid or meteoroid entering the atmosphere. Meteorite: - An object of any size of either an asteroid or meteroid that lands on the earth's surface. What does the TiKus Bode Law allow us to predict? - It allowed human to predict the AU between planets by adding and mulKplying based on simple decimal numbers. It's important to learn whatever we can about asteroids because... a. They represent the very primiKve material leU over from the formaKon of solar system. b. Much water and organic material came to Earth from them c. Sooner or later a large asteroid impact is likely to put an end to many terrestrial species including human Where are most asteroids found in the solar system? - Most are found in the area known as the Main Asteroid Belt between Mars and Jupiter. What are asteroids and meteorites thought to represent? - Ancient Greeks & Romans used to think that meteorites are "betyls" - chunks of the god's house. Meteorites are also found entombed to EgypKan Pharaohs. Overall, they are valued really preciously by ancient Greeks, Romans, & EgypKans. Why did the asteroid belt form between Mars & Jupiter? - Jupiter's huge gravitaKonal pull avoided the planetesimals between Jupiter and Mars to form, resulKng in asteroids that could have formed a planet. This is why there is such a big gap between Mars and Jupiter as there really should be another planet. What are the Kirkwood gaps, and what causes them? lOMoARcPSD|32296826
- The Kirkwood gaps are spaces in the asteroid belt where no asteroids exist. It is caused by the extremely strong gravitaKon of Jupiter in that area which any asteroids entering would get swung out and ]y towards the inner solar system. If all the meteoroids and asteroids in the main asteroid belt coalesced, would there be an addiKonal Earth-sized planet between Mars and Jupiter? - No there wouldn't. Because the sum of everything in the asteroid belt is just a li^le smaller than the moon. Therefore, if possible, the planet would be smaller than the moon. What is the di_erence between C, S and M type asteroids? - C type - Carbon: accounts for 75 percent of the asteroids, high in carbon - S type- Silicate/Silicon: accounts for 17% of asteroids, high in silicon - M-type - Metallic: accounts for the remaining, high in metal/metallic, very re]ecKve/high-albedo Why are some asteroids metallic while others are not? - Really large asteroids undergo di_erenKaKon and can be leU with a nickle-iron core and a metallic body. Are the most primiKve asteroids closer to Mars or Jupiter? - Asteroids with low albedo are believed to be composed of the most primiKve material. Near Mars/Sun most metallic/high-albedo asteroids are found, while closer to the edge of the belt & Jupiter where most carbon/low-albedo asteroids are found. Therefore, the most primiKve asteroids are found closer to Jupiter. Q: How can asteroids be classi2ed using albedo and spectral analysis? A: Asteroids can be classi2ed by using albedos because carbon high asteroids re:ect least light and metallic asteroids re:ect the most light. Similar asteroids with similar light re:ection can be classi2ed similarly. Spectrometers are also used to break down the re:ected light into a spectrum which can tell us which minerals re:ect light. Q: Why are the most plentiful asteroid types (carbonaceous chondrites) the least common meteorites found on Earth? A: Because carbonaceous chondrites are composed of several minerals at a time - meaning they came from one or more planet bodies. Q: What is a diGerentiated body? A: A diGerentiated body is a body that is heated - which causes the melting of interior where metal can sink in. lOMoARcPSD|32296826
Q: Give an example of the kinds of features the spacecraft Dawn has observed on large asteroids. A: 4 Vesta is the largest asteroid and one of the brightest in the sky to the naked eye. Dawn discovered that 4 Vesta has a meta-rich core that is half its diameter. It also found that the biggest mountain on 4 Vesta is bigger than the one on Earth. Q: What is an asteroid family? When two asteroids of unequal size collide, will the fragments come from the larger body or the smaller one? A: Family=The breakup of asteroid into a collection of fragments. When two asteroids collide, the larger asteroid will experience greater stress meaning the collision fragments will usually come from the larger one. Q: Do near Earth objects have circular or elliptical orbits? A: All of them have highly elliptical orbits. Q: De2ne Atens, Apollos, and Amors. A: Atens: Asteroids with orbits less than 1 AU - meaning they are within the orbits of Earth. Apollos: Asteroids that cross the Earth's orbit. Amors: Asteroids that cross the orbit of Mars and get close to Earth's orbit. Q: What is the de2nition of a PHA? A: Potentially Hazardous Asteroids (PHAs) with minimum 150 m diameter and 0.05 AU to Earth. Q: What are Trojan asteroids? A: They are asteroids that are about 60 degrees ahead and behind Jupiter in Jupiter's orbit. Q: What size of an impactor could cause global eGects on Earth? A: Minimum 1km - Apollo asteroids. Q: What is the Torino scale? lOMoARcPSD|32296826
A: A system used to rate the hazard level of an object moving toward Earth. 10 means a collision is certain - capable of causing a global eGect. 0 means a collision's likelihood is zero. Q: What are the sources of meteorites that we have found on Earth? How representative of the sources are the samples? A: Most of the meteorites found on Earth are actually chips from the surface of the Moon and Mars. The sources are representative because they were examined according to the materials collected on the Moon and Mars. Q: What is the diGerence between a 2nd and a fall? A: Find meteorites are found unintentionally with no information of how it got here. Fall meteorites are witnessed through entering the atmosphere and then was recovered by someone. Q: What is the diGerence between irons, stony-irons, and stones? Which is the most commonly found on Earth? A: Stone: non-metallic, make up 93% of all meteorites - divided into chondrites & achondrites. Stony-iron: 50/50 mix of metallic and non-metallic materials, make up 1% of meteorites. Iron: metallic materials (iron + nickle), make up 6% of meteorites. Within the Stones category, what is the di_erence between chondrites and achondrites? - Chondrites: a meteorite that has never been altered or melted Achondrites: - An igneous rock that has been at least parKally melted or recrystallized. What is a chondrule? How might they have formed? - Chondrules are small, rounded inclusions (holes) in chondrite - They are condensed from a hot cloud of gas and dust. very early in the Solar System. Why are scienKsts so excited about studying carbonaceous chondrites? - Carbonaceous chondrites are fascinaKng because they may contain carbon - which may have diamonds, graphite, organic molecules which are the building blocks of life. What is the di_erence between an achondrite and a primiKve achondrite? - Achondrite: An igneous rock which is parKally or fully melted. PrimiKve achondrite: - A residual rock (rock leU behind that didn't melt) What are the possible sources of micro-meteoroids (interplanetary dust)? lOMoARcPSD|32296826
- Interplanetary dust are Solar System's smallest meteoroids which orbit the Sun. The sun's gravity constantly push them out of the solar system so there needs to be sources which constantly replace the ones that are being lost. Asteroids: - Collision in the asteroid belt break into small parKcles which turn into interplanetary dust. Comets: - Dusty trails from comets leU to form the interplanetary dust. How does a meteor shower occur? What is the di_erence between a meteor shower and a Jreball? - Meteor shower comes from speciJc region and strikes the earth's atmosphere at the same posiKon along Earth's orbit. - Fireball: Large chunks of asteroid knocked o_ by collision which light up due to the burning fricKon between its body and the atmosphere. - Di_erence: Meteor show does not reach earth's surface but Jreball is powerful enough to break through and land on earth. How is the light of a Jreball formed? Why do the colours change? - The light of the Jreball is the burning of the body itself caused by ablaKon and the lighKng of atmosphere surrounding it. - The colour is 1. Vaporizing of the material & 2. Luminous air surrounding the Jreball. - Colour changes because elements give o_ di_erent colors when vaporized - Bright white to Red. Are meteorites hot when they land? Why or why not? - Yes, atmosphere heats up meteorites to extremely temperature that ablaKon occurs - losing mass. How does the atmosphere slow a meteoroid's momentum? - Atmosphere slows down its momentum by creaKng drag - slowing down its velocity. Explain how a meteoroid's mass and velocity a_ects its momentum and kineKc energy? - The greater the mass and velocity, the greater the momentum and kineKc energy. Many meteors are destroyed in the atmosphere before they reach the Earth's surface - what kinds of meteors (size, speed are more likely to survive)? - Larger/high velocity/high momentum meteoroids don't survive. If the meteoroids are broken into smaller pieces they have a higher chance of avoiding ablaKon and heaKng. How does atmospheric fricKon a_ect the surface of the meteorite? -Their edges will melt -Surface are marked with thumbprint marks. Where are meteorites on Earth oUen found and why? -Desert / ArcKc - where it's open ground and easy to spot. - AntarcKca is the best place: it's coldness preserve the meteorite, and its open ground. lOMoARcPSD|32296826
What techniques do we use to analyze a meteorite? What can we learn from the test? - Petrographic microscope: IdenKfy mineral composiKon of meteorite. Electron micropobe: - Uses Kny beam of electrons to idenKfy what elements are present. Mass spectrometer: - Measures radioacKve isotopes to see how old sample is. End of Chapter 4 DeJniKons of a gas giant planet (Jovian Planet) - A large, low-density planet composed primarily of hydrogen, helium, methane, and ammonia in gas or liquid state. What are the 4 gas giants in our solar system? - Jupiter, Saturn, Uranus, Neptune What are the common features shared by gas planets? - low density - very hot core - Mainly made of hydrogen and helium, my hydrogen. - All have satellites/rings - All rotate rapidly resulKng in strong atmospheric wind. How/when do the gas giants form? - Either formed in the Jrst 10 million years of solar system or did not develop. - VolaKle and liquid elements - grew via gravitaKonal a^racKon and increased by pulling greater and greater quanKKes of volaKle liquids to them. What did we learn by watching the Shoemaker-Levy 9 comet impacKng Jupiter? - 1. It be^er allowed us to study and represent Jupiter's atmosphere. - 2. It reminded us that planets are being hit by large objects all the Kme. How do we know that Jupiter is big? - We know that Jupiter is big because it looks big. Io's shadow displays visible contrast to Jupiter's size. How do we know that it is hot? Why does it have a high heat ]ow (what is the internal heat engine) - We know that it's hot because it emits 1.7 x energy that it receives from sun - meaning it has a hot core that generates energy. - It has strong wind circulaKon. Describe what we observe happening on Jupiter's surface? - There are very strong winds. the Great Red Spot (GRS) is a cloud of rotaKng storm caused by heat rising upwards. Why did scienKsts crash the Galileo spacecraU into the surface of Jupiter? What did we learn during this descent? - Galileo was crashed to the surface of Jupiter because it could contaminate the icy crust of Europa that main contain microbial life. lOMoARcPSD|32296826
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