Panic

Question 1

CCD

Answer 1

Charge coupled devices

Silicone chips divided into a grid of millions of identical pixels
That can capture images digitally

Question 2

How DO CCDs work

Answer 2

Photons hit silicon in pixel
Creates free electrons confined to the pixel
Causes charge to accumulate
Which can be measured to create digital signal

Describes where light hits an the intensity
Charge varies depending on how many photons hit

Question 3

CCD vs eye

Answer 3

C: quantum efficiency of 80%
E: 1%

C: detect wider spectrum of light (UV and infrared) than E which can only detect visible

C: less convenient, more equipment needed than just looking down telescope

C: creates digital images which can be stored, copied and shared

Question 4

What can limit resolution

Answer 4

Diffraction

Diffraction pattern forms with airy disc at centre and maxima and minima around

Question 5

Air bubbles or impurities in glass

Answer 5

Absorb and scatter some light so faint objects seen

Difficult to build them large

Question 6

Issue with focal length of refracting telescope

Answer 6

Mustbe large to get large magnification

So need large expensive buildings

Question 7

Benefit of reflecting mirrors

Answer 7

No chromatic aberration

Supported from underneath so distort less than lenses

Question 8

Casssegrain arrangement

Answer 8

Uses convex secondary mirror so the user doesn’t block incoming light

Question 9

Radio telescope benefit

Answer 9

Making a dish out of wire mesh makes construction easier and cheaper

Longer wavelength of radiation being detected so less affected by imperfections in shape of dish so dish doesn’t have to be as perfect to avoid spherical aberration

Question 10

Collecting power

Answer 10

Proportional to diameter squared

Question 11

Parallax

Answer 11

Apparent change in motion

Question 12

Distance of a nearby star

Answer 12

d=r/tantheta

For small angles, tan theta is approximately theta

Question 13

0.77 arc seconds

Answer 13

0.77×1/3600

Question 14

Parallax

Answer 14

Half the angle by which a nearby star appears to move in relation to the background stars in 6 months as earth moves from one end of its orbit to the other

Question 15

What objects emit EM radiation

Answer 15

Any above absolute zero

Question 16

Black bpdy

Answer 16

Absorbs all EM radiation of all wavelengths and emits all wavelengths of EM

Question 17

Main sequency

Answer 17

Long lived stable phase

Fusing hydrogen into helium