Chapter 8

Question 1

Effect of Earth’s atmosphere on wavelengths?

Answer 1

Earth’s atmosphere hinders observations at some wavelengths. For example, Gamma rays, X-rays, UV rays, IR and microwave rays get hindered. For optical and IR astronomy, atmospheric turbulence makes observations a little harder.

Question 2

What causes turbulence?

Answer 2

Hot air rising makes turbulence and so does the wind.

Question 3

What are the ideal sites for telescopes?

Answer 3

The ideal sites are mountain tops because they are above much of the turbulence in the atmosphere. Dry sites with consistent weather are the best. Sites far from large population centers mitigate light positions.

Question 4

Ways observatories can and do give back to indigenous communities?

Answer 4

• Leasing land and purchasing utilities from local indigenous tribes.
• Donations and investments in local communities
• Educational outreach programs, some specifically to indigenous communities
• Hiring indigenous staff

Question 5

Problems with telescope locations

Answer 5

• Indigenous people have lost land that astronomers benefitted from.
• Indigenous communities often have limited access to educational resources and infrastructure.

Question 6

What are adaptive optics?

Answer 6

mirrors are deformed in such a way that incoming light is corrected back to flat-plane waves.

Question 7

How to deal with the atmosphere? when looking at Mid-Far infrared, UV and other rays that are blocked by the atmosphere.

Answer 7

Space telescopes avoid the atmosphere effects together.
Pros:
- No atmosphere, so no distortion
- Less constrained by day/night and weather.
Cons:
- Expensive to build
- Hard to reach for service or upgrades
- Limited in size.

Question 8

What is the Nebular Theory of Planet Formation?

Answer 8

1. Interstellar space is not completely empty. and is full of gas and dust called the Interstellar Medium. Dense pockets of gas and dust are called molecular clouds and these are sites of star formation.
2. The cloud is large and diffuses and its rotation is slow.
3. Cloud begins to collapse because of the conservation of energy the cloud heats up as it collapses. As it collapses conservation of angular momentum makes the cloud spin faster.
4. Disks spin faster and becomes flat as it contracts. creating a flat disk with a hot center.
5. Gravity pulls inwards on all gas in the cloud. Materials at the center experience a centrifugal force due to rotation. the poles experience no centrifugal force and continue to collapse inwards.
6. planets and moons all form out of disk material that is all orbiting in the same direction.
7. particles in this disk start to collide and create planetesimals.
8. planetesimals accrete more materials and collide to grow into planets.
9. Inner planetesimals left from planet formation are rocky, these are asteroids. Outer planetesimals left over from planet formation are rocky and icy.

Question 9

What is the frost line?

Answer 9

The frost line helps explain how the inner region of the disk is hot as a result rocks and metals are the only solids. Gases are still gas. But as you move further away from the sun the outer region of the disk is cooler, which means that some materials condense into ice. in this region, you have rocks, metals and ice

Question 10

What happened during the heavy bombardment period?

Answer 10

Interactions with outer giant planetssent many asteroids and comets crashing into terrestial planets. This where we think water on earth came from.

Question 11

How do we believe Earth’s moon formed?

Answer 11

We believe that a large mars sized planet hit the earth during its early stages and resulted in the debris from its impact collected in an orbit around Earth to form the moon.

Question 12

3 types of space missions?

Answer 12

1. Flyby missions - where we send a robot to space to fly by another object. these are less expensive because they carry less fuel and use gravity assists for acceleration.
2. Orbiters - Missions that reach a planet and stay in the orbit around it. Require fuel and or use gravity to adjust their paths and carry cameras, spectrometers, etc
3. Landers - they land on planets and can interact with materials on the surface, so carry different types of instruments. Rovers are likely landers but can move.

Question 13

Sample return missions

Answer 13

-only gone to the moon and a few asteroids
-very expensive, since aircraft needs fuel to return back to earth.

Question 14

How can we tell how old the solar system is?

Answer 14

Radioactive decay and half life in specifc carbon decay