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Earth 2
Lecture 16- No craters, not asked?
| Question | Answer |
|---|---|
| There were multiple attempts to explain where the moon came from | A body trapped by earth's gravity, a centripetal bulge escaping the earth, a collision with giant planetoid creating the moon |
| Observations of the moon helped constrain the kind of models that could be used | Age of moon (100 million years younger than earth), similar chemistry to earth, angular momentum |
| Canadian craters | many craters are very old, hundreds of millions of years old, and weathering has been erasing them. The craters also often take the form of lakes. |
| Impact on Mars 21 December 2021 | 5-12m diameter meteoroid. 150m diameter crater, 21m deep crater. Seismometers on mars felt a marsquake. Scientists used satellite images to search for impact site |
| Bollides | asteroids, comets, meteoroids, meteors, meteorites |
| Asteroids | Current count: 1,267,131. They are 10m-530km in diameter. Three types: C-type, S-type, M-type. In space! VERY LARGE |
| C-type asteroid | chondrite: clay and rock |
| S-type asteroid | Stony: rock and nickel/iron |
| M-type asteroid | metallic: nickel/iron |
| Comets | Composed of frozen water, ammonia, hydrocarbons, dust and rocks. Commet C/2022 E3 (ZTF). Orbit is extremely elliptical compared to the planets |
| Anatomy of comets | Nucleus-solid part. Coma-cloud of gas surrounding nucleus. Ion tail- (ionic gas molecules ALWAYS POINTS AWAY FROM SUN) blown by solar winds. Dust tail-liberated dust that trails the comet (follows direction its moving) |
| Meteoroids | Dust to small asteroids in space. Tiny. |
| Meteors | When a meteoroid enters the atmosphere and become "shooting stars" . Not ending in -oids means it is in earth |
| Meteorite | A meteor that survives the journey through the atmosphere and hits the ground |
| Achondrite | Type of meteorite. Produced by melting of parent asteroid |
| Chondrite | type of meteorite. Altered material but not melted |
| Stony-iron meteorite | mostly stone and iron/nickel |
| iron meteroite | mostly iron/nickel |
| Where do asteroids and things come from? | Oort cloud and Kuiper Belt, asteroid belt |
| What happens on approach (of NEOs) | Atmosphere is about 80KM thick, but most of it is the closest 16KM. At 30km/h it would only take seconds for an asteroid to pierce the atmosphere. It creates a vacuum (in the vid) |
| Crater formation and anatomy | crater, ejecta, shocked minerals (quartz), spherules |
| Energy | You can easily estimate the impact energy of an asteroid by calculating the kinetic energy of the asteroid just before it strikes the earth. This is equal to the impact energy |
| Torino Scale | Where other scales are measurements during the event, or after the event, the Torino scale categorizes POTENTIAL impact event PROBABILITY and projected consequences |
| Palermo scale | A more complex Torino scale. R<-2, likely no consequences. R=0, average background hazard. R>0 Situation merits concern |
| Mitigating the hazard | identify the asteroid, calculate potential impacts with Earth Size and speed of object. Palermo (and Torino) scale designation |
| DART | Double Asteroid Redirection Test. Crash a probe into the side of the smaller asteroid, changed the orbit of the little asteroid. Should change the trajectory of the asteroid system |
| What can we do with NEOs? | Look for them, find them, calculate orbits |
| What can we do with NEOs that pose a threat? | Move with a hit, ram a ship into the asteroid. Move with a pull: use the weight of a small ship to slowly pull the asteroid into a new orbital trajectory |
Created by:
user-1996284