AS101 Assignment 5

Which power of a telescope reveals fine details within an image?

resolving power

Which of the following types of light has wavelengths that are longer than the wavelengths of visible light?

infrared

What is a photon?

a particle of light

Which of the following best explains the concept of atmospheric windows?

Only certain wavelengths of electromagnetic radiation from space reach Earth's surface.

What is the purpose of interferometry?

It is used to improve the resolving power of telescopes.

No radio waves penetrate the Earth's atmosphere.

False

Light-gathering power and resolving power both depend on what characteristic of a telescope?

diameter

What modern-day instrument do astronomers use to record images from telescopes?

charge-coupled device

What does a nanometre measure?

length

What is the relationship between colour and wavelength for light?

Wavelength increases from blue light to red light.

Which of the following types of electromagnetic radiation is absorbed by ozone in the Earth's atmosphere?

ultraviolet radiation

What type of telescope is a radio telescope?

reflecting

What is the main reason for building large optical telescopes?

It's the best way to collect as much light as possible from faint objects.

An array of telescopes work together as an interferometer. How would the interferometer's performance change if many more telescopes were added between the existing telescopes?

The resolving power would stay the same and the light-collecting power would increase.

Radio telescopes are often located near populated areas

False

Refracting telescopes use a mirror to gather and focus light

False, they use lenses

Refracting and reflecting telescopes form an image that is small, inverted, and difficult to observe directly; therefore an eyepiece is normally used to magnify the image and make it convenient to use

True

​The larger the diameter of a telescope, the more light it will collect.

True

Resolving power is measured in nanometers

False

All telescopes must be operated on site by an astronomer or a technician.

False

The amount of energy a photon carries depends on its wavelength.

True

Where would you most likely find a large radio telescope?

in a mountain valley

Visible light with wavelengths at the long-wavelength end (λ = 700 nm) appears as which color?

red

​A spectrograph spreads out light according to ____ to form a spectrum.

wavelength

​What does a refracting telescope use to gather and focus light?

lens

Which part of a telescope is responsible for magnifying an image?

eyepiece

Jenny, who lives on a farm in a rural part of New York, calls her cousin, Karen, in Brooklyn, to tell her that she can see the Milky Way in tonight's night sky. However, Karen says she can't see it at all. What is preventing Karen from seeing the Milky Way in the night sky?

Karen lives in an area with light pollution.

What type of electromagnetic radiation does Chandra telescope collect?

X-ray

​If telescope A is 160 cm in diameter, and telescope B is 32 cm in diameter, how much more light does telescope A gather than telescope B?

25 times

Why are X-rays and gamma rays considered dangerous forms of light?

Photons of these wavelengths have high energy.

​The ____ of a radio telescope collects and focuses radiation.

dish

​Which form of electromagnetic radiation is able to easily reach Earth's surface through an atmospheric window?

radio

​What unit is used to measure wavelengths?

nanometer

The energy a photon carries is inversely proportional to __________.

its wavelength

​What characteristic of a telescope controls the amount of light captured by the telescope?

diameter of tube

Which is the longest surviving, and most successful, space telescope?

Hubble Space Telescope

Which form of radiation has the lowest frequency?

microwave

What does the word "radiation" mean when used by scientists?

anything that spreads out from a central source

In which way is a photon of blue light identical to a photon of red light?

speed

Why do astronomers build radio telescopes?

Radio waves give a different view of the universe.

An astronomer takes two pictures of the same object using the Hubble Space Telescope. One picture is taken with red light and one with blue light. Which one would you expect to show finer details?

Blue light will show finer details.

What is the light-gathering power of a telescope directly proportional to?

the diameter of the primary mirror or lens

Why can't a telescope image be magnified to show any level of detail?

Diffraction limits the amount of detail that is visible.

Which of the following has the most light-gathering power?

a telescope of 6 centimetres diameter and focal length of 100 centimetres

The pupil of the human eye is approximately 0. 8 centimetres in diameter when adapted to the dark. What is the ratio of the light-gathering power of a 1. 6 metre telescope to that of the human eye?

40,000 : 1

By what factor is the light-collecting power of the James Webb Space Telescope (6.6 m primary mirror) greater than the light-collecting power of the Hubble Space Telescope (2.4 m primary mirror)?

7.56

Space telescope A has a diameter of 2. 4 metres; space telescope B has a diameter of 6. 5 metres. If they take pictures with the same wavelength of light, which telescope will be better able to make separate images of two stars close together on the sky?

Telescope B will do better.

Why do radio telescopes have poor resolving power?

Radio waves have long wavelengths.

Your favorite radio station broadcasts at a frequency of 1.00 × 108 Hz. What is the wavelength of this transmission?

3 m

Which of the following statements best explains why stars twinkle?
variations in the diffraction limit of the atmosphere
bending of ultraviolet rays as they reflect back into space
bending of light rays by turbulent layers in the atmosphere
differential bending of visible wavelengths in the middle atmosphere

bending of light rays by turbulent layers in the atmosphere