Telescopes and Space Probes

Question 1

What are the two basic telescopes?

Answer 1

Reflectors and refractors

Question 2

What type of lens does a refracting telescope use?

Answer 2

Convex Lens

Question 3

What type of lens does a reflecting telescope use?

Answer 3

Parabolic (Concave) Lens

Question 4

What does an objective element do?

Answer 4

It collects as much light as possible and focuses it into a small, bright image

Question 5

What does an eyepiece lens do?

Answer 5

An eyepiece lens magnifies the image given by the objective element so we can see an image in high resolution

Question 6

What are the differences with a larger telescope?

Answer 6

• More light enters the telescope; making the image brighter

- There is a higher resolution and a bigger amount of detail

Question 7

What does the resolution depend on (in terms of wavelengths)?

Answer 7

The wavelength of light that is entering the telescope; a red nebulae has a lower resolution compared to a blue nebulae as red has a longer wavelength

Question 8

What determines a telescope’s magnification?

Answer 8

The ratio of the lengths of the objective and and eyepiece

Question 9

What is the equation for magnification?

Answer 9

. . . . . . . . . . . . . . .focal length of objective. . . fo
magnification = ———————————– = —-
. . . . . . . . . . . . . . .focal length of eyepiece. . . fe

Question 10

Name two ways you can get greater magnification

Answer 10

• Use eyepieces of different focal lengths; the shorter the focal length, the greater the magnification
• Use a Barlow Lens

Question 11

What is a Barlow Lens?

Answer 11

A Barlow lens a piece of kit for astronomers that slots into the eyepiece and increases the magnification by 2x or 3x

Question 12

What is Field Of View (FoV)?

Answer 12

The field of view of a telescope is the circle of the sky that is visible through the eyepiece

Question 13

What is a parabolic mirror?

Answer 13

A concave mirror that transforms a plane wave into a spherical wave that moves into the centre

Question 14

What are the 4 main sources of light pollution?

Answer 14

• Commercial and sports floodlights
• Urban street lamps and motorway lights
• Domestic and industrial security lights
• Lights above car parks and shopping centres

Question 15

How long is 1 AU?

Answer 15

1 AU = 150 Million km = Distance from the Earth to the Sun

Question 16

How long is one light year?

Answer 16

1 l.y. = 9,500,000,000,000 km= 9.5 billion km

Question 17

How long is one Parsec?

Answer 17

1 pc = 3.26 l.y. = 3.1 × 10¹³ km

Question 18

What is an H-Alpha Filter?

Answer 18

An H-Alpha filter is a filter which is designed to transmit a narrow bandwidth of light. It can be used to observe the features of the Sun

Question 19

Which photoreceptors in a human eye respond to bright lights?

Answer 19

Cones

Question 20

What is the approximate diameter of the pupil of the human eye in bright light?

Answer 20

3 mm

Question 21

What is Dark Adaption?

Answer 21

Dark Adaption is an observing technique where the observer spends time to allow the retina’s rods to desensitise so dimmer stars become more visible

Question 22

What are the components of a reflecting telescope?

Answer 22

A reflecting telescope consists of a Concave mirror and Convex lens

Question 23

What is the objective element of a reflecting telescope?

Answer 23

Converging mirror

Question 24

Which telescope does an observer not look along its optical axis?

Answer 24

Newtonian Reflector

Question 25

Which telescope uses a small diverging secondary mirror to reflect to reflect light back down the 'tube'?

Answer 25

Cassegrain Reflector

Question 26

What is a finderscope?

Answer 26

A finderscope is a smaller telescope attached to larger reflectors

Question 27

What is more important: Resolution or Magnification

Answer 27

Resolution

Question 28

How is a Keplerian refractor different to a Galilean refractor?

Answer 28

A Keplerian refractor consists of two concave lenses whereas, a Galilean refractor has one

Question 29

What is the resolution of a telescope proportional to?

Answer 29

Resolution of a telescope proportional to the diameter of the objective element

Question 30

A small inexpensive telescope would be most likely what type of telescope?

Answer 30

Keplerian Refractor

Question 31

What are the advantages of having a reflecting telescope over a refractor?

Answer 31

- Higher magnifications - Larger objective diameters - Shorter physical lengths

Question 32

What was the space probe Magellan's target?

Answer 32

Venus / Orbiter

Question 33

What was the space probe New Horizon's target?

Answer 33

Pluto & outer Solar System / Fly-by

Question 34

What was the space probe Deep Impact's target?

Answer 34

Comet Tempel 1 / Impactor

Question 35

What was the space probe Juno's target and what type of probe was it?

Answer 35

Jupiter / Orbiter

Question 36

What was the space probe Huygens' target and what type of probe was it?

Answer 36

Titan / Lander

Question 37

Which space probe made detailed studies of asteroids Vesta and Ceres from orbit?

Answer 37

Dawn

Question 38

What are the advantages of a unmanned mission compared to a manned mission?

Answer 38

Unmanned missions are cheaper, there is no danger faced towards humans and there are no communication time delays as the mission is pre-programmed with mission commands without the need for human interference

Question 39

Which twin space probes studied the outer gas planets, their ring systems and moons?

Answer 39

Voyager

Question 40

What was the space probe Philae's target and what type of probe was it?

Answer 40

76P/Churyumov-Gerasimenko / Lander

Question 41

What was the Purpose of Philae?

Answer 41

- To make detailed studies of the surface of a comet (including an analysis of its water). - A chemical composition of comet’s surface (including ammonia, hydrogen cyanide and hydrogen sulfide) - Discovery of amino acids in ‘haze’ around the nucleus - The shape of comet implied that it was initially two separate bodies that fused together billions of years ago - Analysis of water content found much larger abundance of H-2 isotope (deuterium) suggesting water was not deposited on Earth by comets.