Lecture 6 Flashcards Preview

AST205 > Lecture 6 > Flashcards

Flashcards in Lecture 6 Deck (39)
Loading flashcards...
1
Q

What is the approximate mass of planet 9?

A

10x earth

2
Q

Approximately how long is Planet 9’s orbit?

A

10,000 to 20,000 years

3
Q

How was Uranus discovered and by whom?

A

Herschel, via his telescope, in 1781

4
Q

How was Neptune discovered?

A

By calculations based on anomalies in Uranus’s orbit

5
Q

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

A

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

6
Q

Is P9 a typical planet?

A

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

7
Q

What would planet 9 explain?

A

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

8
Q

What is refraction?

A

It is the bending of light

9
Q

What parts of the eye make up the “Telescope”?

A

Cornea and Lens

10
Q

What is the effect of refraction on parallel rays?

A

It makes them converge in a focal point

11
Q

How do Daguerrotypes work?

A

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

12
Q

What star was first captured in an image?

A

Vega, in 1850

13
Q

What are the limitations of photomultiplier tubes?

A

They can only measure one light-source

14
Q

What are the two most important parts of a telescope?

A

The light-collecting area and the angular resolution

15
Q

A larger light-collecting area means…

A

greater amount of light in a shorter amount of time

16
Q

A larger telescope’s angular resolution can…

A

take in greater detail

17
Q

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

A

Because light is diffracted in the telescope aperture

18
Q

What ultimately limits resolution?

A

Interference of waves in a telescope

19
Q

What are the two basic types of telescopes?

A

Reflecting and Refracting

20
Q

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

A

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

21
Q

Are most modern telescopes refractors or reflectors?

A

Reflectors, because making large glass is too cumbersome

22
Q

What are the three types of foci?

A

Newtonian, Cassegrain, and Nasmyth

23
Q

What is unique about a Newtownian focus?

A

it is towards the top of the telescope

24
Q

What is unique about a Cassegrain focus?

A

It is at the butt of the telescope

25
Q

What is unique about the Nasmyth focus?

A

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

26
Q

What are the four uses of telescopes?

A

Imaging, Photometry, Spectroscopy, Timing

27
Q

What is the act of imaging?

A

taking photos of the night sky with a camera

28
Q

What is the act of photometry?

A

Recording the brightness of a source.

29
Q

What is the act of Spectroscopy?

A

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

30
Q

What is the act of timing?

A

Recording changes in brightness over time

31
Q

Whose was the biggest early telescope?

A

Herschel (48”)

32
Q

Whose telescope was bigger than Herschel’s?

A

Lord Rosse’s leviathan

33
Q

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

A

Harvard’s 15” refractor

34
Q

What was the biggest working refractor?

A

Yerkes’s 40”

35
Q

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

A

High, dark, dry, cold

36
Q

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

A

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

37
Q

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

A

Adaptive optics

38
Q

What kind of telescopes Need to be in space?

A

Radio, gamma, x-ray, and neutrino telescopes

39
Q

What is interferometry?

A

The linking of multiple telescopes together to achieve higher angular resolution