Chapter 12

Question 1

What is Deep Impact?

Answer 1

Mission to study the nucleus of Comet Tempel 1
A Projectile hit it’s surface in 2005
Many telescopes studied the aftermath

Question 2

Anatomy of a Comet

Answer 2

• Coma
• Plasma Tail
• Dust Tail

Question 3

(Comets) Coma

Answer 3

The atmosphere that comes from a comet’s heated nucleus

Question 4

(Comets) Plasma Tail

Answer 4

Gas escaping from coma, pushed by the solar wind

Question 5

(Comet) Dust Tail

Answer 5

Its pushed by photons

Question 6

Growth of Comet Tail

Question 7

Rosetta Mission

Question 8

Meteors in Meteor Showers

Answer 8

They appear to emanate from the same area of the sky because of Earth’s motion through space

Answer 9

Comets eject small particles that follow the comet around in its orbit and causes the meteor showers when Earth crosses the comet’s orbit

Question 10

Where Do Comets Come From?

Answer 10

A tiny number come form the inner solar system.
Oort Cloud
Kuiper Belt

Question 11

Comets from the Oort Cloud

Answer 11

They have random orbits extending 50,000 AU

Question 12

Comets from the Kuiper Belt

Answer 12

They have orderly orbits from 30 to 100 AU in the disk of the Solar System

Question 13

How did Comets get in the Oort Cloud?

Answer 13

These comets were once closer to the Sun, but they were kicked out there by gravitational interactions with Jovian planets: spherical distribution, orbits in any direction

Question 14

How did Comets get in the Kuiper Belt?

Answer 14

These comets formed in the Kuiper belt: flat plane, aligned with the plane of planetary orbits, orbiting in the same direction as the planets

Question 15

Pluto’s Orbit

Answer 15

It will never hit Neptune, even though their orbits cross, because of their 3:2 orbital resonance.
Neptune orbits three times during the time Pluto orbits twice

Question 16

What is Pluto Like?

Answer 16

• Its moon Charon is nearly as large as Pluto itself
• Very Cold (40 K)
• A thin nitrogen atmosphere that will refreeze on the surface as Pluto’s orbit goes farther from the Sun
• Active geology

Question 17

New Horizons

Question 18

The International Astronomical Union (IAU) now classifies Pluto and Eris as

Answer 18

Dwarf Planets

Question 19

Do catastrophic collisions still happen?

Answer 19

Yes, 1994 Jupiter was violently impacted by Comet SL9

Question 20

Jupiter Recent Impacts

Answer 20

1994 Jupiter was violently impacted by Comet SL9, after it was tore apart by tidal forces
There is a black spot from when it was struck by an unknown object in 2009

Question 21

Mass Exinction Evidence

Answer 21

• Iridium
• Fossil Records

Question 22

Iridium

Answer 22

Very rare in Earth’s surface and often found in meteorites

Question 23

What are the consequences of an Impact?

Answer 23

• A meteorite 10km in size would send large amounts of debris into the atmosphere
• Debris would reduce sunlight reaching the surface
• Resulting climate change could have cause mass extinction

Question 24

Where is the likeliest impact site for the meteor that killed the dinosaurs?

Answer 24

• A large subsurface crater ~65 million years old in Mexico

Question 25

How Great in the risk of an Impact today?

Answer 25

- Asteroids/comets have hit Earth - Its only a matter of time - Major impacts are rare

Question 26

Whats the frequency of impacts?

Answer 26

- Small impacts happen almost daily - Extinction level: million of years apart - Major damage: tens of hundreds of years apart

Question 27

Where is THE world ending asteroid?

Answer 27

- We haven't seen it yet - Deflection is more probably with years of advanced warning - There will be less of an advance warning of a killer comet....

Question 28

Whats the influence of Jovian planets with comets?

Answer 28

Gravity of a Jovian planet (especially Jupiter) can redirect a comet. Jupiter has directed some comets toward Earth but has ejected many more into the Oort cloud.