Question 1

Suppose you have two small photographs of the Moon.Although both look the same at small size,when you blow them up to poster size one of them still looks sharp while the other one becomes fuzzy (grainy)looking.Which of the following statements is true?

Accepted Answer

Angular resolution refers to the ability of an imaging system to distinguish between two closely spaced objects. If one photograph looks sharper at larger size than the other, it means that it has better angular resolution, or in other words, it can better distinguish between small details on the Moon's surface. Therefore, choice A is the correct answer.

Question 2

Which of the following studies is best suited to astronomical observations that fall into the category called timing?

Accepted Answer

Studying how a star's brightness varies over a period of 3 years falls under timing observations, as it involves measuring changes in a celestial object over a specific time period. The other options do not involve observing changes over time and are not suited to timing observations.

Question 3

What is the purpose of interferometry?

Accepted Answer

Interferometry involves combining the signals from multiple telescopes to produce an image with higher angular resolution than any single telescope could achieve. This allows two or more small telescopes to work together to achieve the same resolution as a much larger telescope.

Question 4

Which of the following wavelength regions can be studied with telescopes on the ground?

Accepted Answer

Telescopes on the ground can observe radio waves, visible light, and limited portions of the infrared and ultraviolet regions. Other wavelengths, such as X-rays and gamma rays, cannot penetrate Earth's atmosphere and require space-based telescopes.

Question 5

Consider two future observatories in space.Observatory X consists of a single 50-meter telescope.Observatory Y is an interferometer consisting of five 10-meter telescopes,spread out over a region 100 meters across.Which observatory can detect dimmer stars,and which one can see more detail in its images? (Assume all else is equal,such as quality of optics,types of instruments,and so on. )

Accepted Answer

The ability to detect dimmer stars is directly related to the collecting area of the telescope, and a single 50-meter telescope has a larger collecting area than a 10-meter telescope. Therefore, Observatory X can detect dimmer stars. The ability to see more detail, or the resolving power, is greater for telescopes that are spread out over a larger area, as in an interferometer. Thus, Observatory Y, with its telescopes spread out over 100 meters, can see more detail in its images.

Question 6

Which of the following is not an advantage of the Hubble Space Telescope over ground-based telescopes?

Accepted Answer

The option "It is closer to the stars" is not an advantage of the Hubble Space Telescope over ground-based telescopes because both types of telescopes observe the same stars from a distance.

Question 7

Which of the following telescopes would benefit most from adaptive optics?

Accepted Answer

The Keck I Telescope on Mauna Kea is a ground-based telescope which is affected by atmospheric distortions. Adaptive optics would correct for these distortions and provide sharper images. The other telescopes listed are not affected by atmospheric distortions and would not benefit as much from adaptive optics.

Question 8

Which of the following best describes the development of astronomical telescopes over the past 60 years?

Accepted Answer

The development of astronomical telescopes over the past 60 years can be described as a transition from a single most powerful telescope to many new and more powerful telescopes being built in the last two decades. This is supported by advancements such as the Hubble Space Telescope, Keck Observatory, and the upcoming James Webb Space Telescope. Therefore, option C is the most accurate description. Option A and D are incorrect as they overgeneralize and do not account for the nuances in development. Option B is also inaccurate as there have been significant advancements in telescope technology over the past 60 years.

Question 9

The Chandra X-Ray Observatory must operate in space because

Accepted Answer

X-rays are absorbed by Earth's atmosphere, making it impossible to observe them from the ground. Therefore, spacecraft like the Chandra X-Ray Observatory are necessary to study X-ray sources in the universe.

Question 10

The stars in our sky twinkle in brightness and color because of

Accepted Answer

The twinkling of stars is caused by turbulence in the Earth's atmosphere, which causes the light to be refracted and scattered in different directions, leading to changes in brightness and color as the light reaches our eyes. This effect is particularly noticeable when stars are low on the horizon, as their light has to pass through more of the atmosphere to reach us.

Question 11

Suppose you point your telescope at a distant object.Which of the following is not an advantage of taking a photograph of the object through the telescope as compared to just looking at the object through the telescope?

Accepted Answer

Photographs do not inherently have better angular resolution than the human eye when both are using the same telescope. Angular resolution is primarily determined by the telescope's optics and the observing conditions, not the recording method (photography vs. visual observation).

Question 12

The James Webb Space Telescope is scheduled to launch in 2018.In what range of the electromagnetic spectrum will it operate?

Accepted Answer

The James Webb Space Telescope is designed to operate in the infrared range of the electromagnetic spectrum. It will be able to detect light beyond what is visible to the naked eye, allowing astronomers to observe distant objects such as early galaxies and planets outside our solar system.

Question 13

Why is it important that the James Webb Space Telescope will be operating in the infrared?

Accepted Answer

Operating in the infrared will allow the James Webb Space Telescope to detect highly redshifted light from distant galaxies, which will enable us to observe them as they first formed in the early universe.

Question 14

How does the light-collecting area of an 8-meter telescope compare to that of a 2-meter telescope?

Accepted Answer

The light-collecting area of a telescope is proportional to the square of its diameter. Therefore, the light-collecting area of the 8-meter telescope is (8/2)^2= 16 times that of the 2-meter telescope. So, the correct answer is A.

Question 15

Which of the following is not a reason why telescopes tend to be built on mountaintops that are relatively far from cities and are in regions with dry climates?

Accepted Answer

This is not a reason why telescopes tend to be built on mountaintops that are relatively far from cities and are in regions with dry climates. The other options all explain why these locations are preferred for telescope construction.

Question 16

Which of the following best describes the principle advantage of CCDs over photographic film?

Accepted Answer

CCDs have a higher quantum efficiency, meaning they can capture a larger percentage of incoming photons compared to photographic film. This results in higher sensitivity, better signal-to-noise ratios, and improved image quality.

Question 17

Which of the following is not a major reason why astronomers would like an observatory on the far side of the Moon?

Accepted Answer

Telescopes on the Moon would not see all parts of the sky equally well; their view would still be limited by the Moon's rotation and position.

Question 18

What is the purpose of adaptive optics?

Accepted Answer

Adaptive optics is a technology that uses deformable mirrors to correct for the atmospheric turbulence that causes blurring in images taken from ground-based telescopes.

Question 19

The angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond.What will you see?

Accepted Answer

The angular resolution of the telescope is not fine enough to distinguish between the two stars, and they will appear as one in the photograph.

Question 20

Which of the following best describes why radio telescopes are generally much larger in size than telescopes designed to collect visible light?

Accepted Answer

Radio waves have much longer wavelengths than visible light. Longer wavelengths have lower frequencies and lower energies. This means that to achieve the same angular resolution (ability to distinguish between two points that are close together) as a visible light telescope, a radio telescope needs to be much larger. This is why radio telescopes are generally much larger in size than telescopes designed to collect visible light.

Quiz 6: Telescopes: Portals of Discovery

Suppose you have two small photographs of the Moon.Although both look the same at small size,when you blow them up to poster size one of them still looks sharp while the other one becomes fuzzy (grainy) looking.Which of the following statements is true?