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Flashcards in Lecture 6 Deck (39):
1

What is the approximate mass of planet 9?

10x earth

2

Approximately how long is Planet 9's orbit?

10,000 to 20,000 years

3

How was Uranus discovered and by whom?

Herschel, via his telescope, in 1781

4

How was Neptune discovered?

By calculations based on anomalies in Uranus's orbit

5

What was one of the earliest pieces of evidence for planet 9?

Elongated orbits of some kuiper belt objects all tilted and elongated in the same direction

6

Is P9 a typical planet?

Yes, most planets have a mass between 1 and 10 of Earth's

7

What would planet 9 explain?

Some of the oddities in the solar axis, some of the odd orbits of kuiper belt objects

8

What is refraction?

It is the bending of light

9

What parts of the eye make up the "Telescope"?

Cornea and Lens

10

What is the effect of refraction on parallel rays?

It makes them converge in a focal point

11

How do Daguerrotypes work?

A copper plate with silver and iodine fumes, which is light-sensitive

12

What star was first captured in an image?

Vega, in 1850

13

What are the limitations of photomultiplier tubes?

They can only measure one light-source

14

What are the two most important parts of a telescope?

The light-collecting area and the angular resolution

15

A larger light-collecting area means...

greater amount of light in a shorter amount of time

16

A larger telescope's angular resolution can...

take in greater detail

17

Why do stars appear to have a finite size in a telescope?

Because light is diffracted in the telescope aperture

18

What ultimately limits resolution?

Interference of waves in a telescope

19

What are the two basic types of telescopes?

Reflecting and Refracting

20

What is the difference between a reflecting and a refracting telescope?

Lenses in a refracting telescope are glass, lenses in a reflecting telescope are mirror

21

Are most modern telescopes refractors or reflectors?

Reflectors, because making large glass is too cumbersome

22

What are the three types of foci?

Newtonian, Cassegrain, and Nasmyth

23

What is unique about a Newtownian focus?

it is towards the top of the telescope

24

What is unique about a Cassegrain focus?

It is at the butt of the telescope

25

What is unique about the Nasmyth focus?

It is towards the bottom, on the side of the telescope

26

What are the four uses of telescopes?

Imaging, Photometry, Spectroscopy, Timing

27

What is the act of imaging?

taking photos of the night sky with a camera

28

What is the act of photometry?

Recording the brightness of a source.

29

What is the act of Spectroscopy?

Recording the light divided into spectra, to reveal information about the composition of objects

30

What is the act of timing?

Recording changes in brightness over time

31

Whose was the biggest early telescope?

Herschel (48")

32

Whose telescope was bigger than Herschel's?

Lord Rosse's leviathan

33

What was the biggest telescope in America during the mid-1800s?

Harvard's 15" refractor

34

What was the biggest working refractor?

Yerkes's 40"

35

What are the four criteria for good earth-based observations?

High, dark, dry, cold

36

What about the atmosphere makes it difficult to observe from the ground?

Hot and cold air refract light differently, and the atmosphere is a constantly shifting mix of hot and cold air.

37

What method can telescopes use to minimize the interference of the atmosphere?

Adaptive optics

38

What kind of telescopes *Need* to be in space?

Radio, gamma, x-ray, and neutrino telescopes

39

What is interferometry?

The linking of multiple telescopes together to achieve higher angular resolution