Astronomy Questions chapter 5-7

Betelgeuse is the bright red star representing the left shoulder of the constellation Orion. All the following statements about Betelgeuse are true. Which one can you infer from its red color?

Its surface is cooler than the surface of the Sun.

Suppose a photon has a frequency of 300 million hertz (300 megahertz). What is its wavelength?

1 meter

Suppose you have a 100-watt light bulb that you leave turned on for one minute. How much energy does it use?

6,000 joules

How is Einstein's famous equation, E=mc2, important in understanding the Sun?

It explains the fact that the Sun generates energy to shine by losing some 4 million tons of mass each day.

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

It is closer to the stars.

In what way is Pluto more like a comet than a planet?

It is made mostly of rock and ice.

Which of the following statements about the object called Eris is not true?

It is thought to be the first example of a new class of object.

Why has NASA sent recent orbiters to Mars (such as Mars Reconnaissance Orbiter) on trajectories that required them to skim through Mars's atmosphere before settling into their final orbits?

It saves money because the spacecraft uses atmospheric drag to slow down rather than needing to carry enough fuel to slow by firing rocket engines.

Imagine that an alien spaceship crashed onto Earth. Which statement would most likely be true?

It would crash in the ocean.

Suppose you had molecular oxygen (O2) chilled enough so that it was in liquid form. Which of the following best describes the phase changes that would occur as you heated the liquid oxygen to high temperature?

It would evaporate into a gas, then the molecules would dissociate into individual oxygen atoms, then the atoms would become increasingly ionized as you continued to raise the temperature.

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

The 8-meter telescope has 16 times the light-collecting area of the 2-meter telescope.

Which of the following telescopes benefits most from adaptive optics?

The Keck I telescope on Mauna Kea

Consider the following statement: "Rocky asteroids are found primarily in the asteroid belt and Kuiper belt while icy comets are found primarily in the Oort cloud." What's wrong with this statement?

The Kuiper belt contains icy comets, not rocky asteroids.

Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space?

The cloud is cool and lies between you and a hot star.

The following statements are all true. Which one counts as an "exception to the rule" in being unusual for our solar system?

The diameter of Earth's Moon is about 1/4 that of Earth.

Which of the following statements about thermal radiation is always true?

A hot object emits more radiation per unit surface area than a cool object.

Which of the following is not a real difference between asteroids and comets?

Asteroids orbit the Sun while comets just float randomly around in the Oort cloud.

Each of the following describes an "Atom 1" and an "Atom 2." In which case are the two atoms different isotopes of the same element?

Atom 1: nucleus with 7 protons and 8 neutrons, surrounded by 7 electrons; Atom 2: nucleus with 7 protons and 7 neutrons, surrounded by 7 electrons

Venus has a higher average surface temperature than Mercury. Why?

Because its surface is heated by an extreme greenhouse effect.

In what way is Venus most similar to Earth?

Both planets are nearly the same size.

Consider an atom of oxygen in which the nucleus contains 8 protons and 8 neutrons. If it is doubly ionized, what is the charge of the oxygen ion and how many electrons remain in the ion?

Charge = +2; number of remaining electrons = 6.

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

Closer to the stars (advantages include-- stars do not twinkle when observed from space, the ability to observe infarred, ultraviolet, and visible light, and it never has to close due to cloudy skies)

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

Getting an image of the same angular resolution requires a much larger telescope for radio waves than for visible light.

Why was it advantageous for the Voyager mission to consist of flybys rather than orbiters?

Each individual spacecraft was able to visit more than one planet.

Which of the following statements about electrons is not true?

Electrons orbit the nucleus rather like planets orbiting the Sun.

Which of the following is not a major pattern of motion in the solar system?

Nearly all comets orbit the Sun in same direction and roughly the same plane.

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.)

Observatory X can detect dimmer stars and Observatory Y reveals more detail in images.

Suppose that 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. How will the stars appear in the photograph?

Since their angular resolution is smaller than the telescope's angular resolution, your photograph will seem to only show one star rather than two.

Suppose that Star X and Star Y both have redshifts, but Star X has a larger redshift than Star Y. What can you conclude?

Star X is moving away from us faster than Star Y.

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

Studying how a star's brightness varies over a period of 3 years.

Suppose that two stars are identical in every way - for example, same distance, same mass, same temperature, same chemical composition, and same speed relative to Earth - except that one star rotates faster than the other. Spectroscopically, how could you tell the stars apart?

The faster rotating star has wider spectral lines than the slower rotating star.

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?

The one that still looks sharp at large size has better (smaller) angular resolution than the one that looks fuzzy.

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?

The photo will seem to show only one star rather than two.

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?

The photograph will provide a more reliable record of what is seen through the telescope than can a drawing made by eye, it can allow you to see objects that would be too dim for you to see with your eye

If we observe one edge of a planet to be redshifted and the opposite edge to be blueshifted, what can we conclude about the planet?

The planet is rotating.

Suppose you are listening to a radio station that broadcasts at a frequency of 97 Mhz (megahertz). Which of the following statements is true?

The radio waves from the radio station are causing electrons in your radio's antenna to move up and down 97 million times each second.

Laboratory measurements show hydrogen produces a spectral line at a wavelength of 486.1 nanometers (nm). A particular star's spectrum shows the same hydrogen line at a wavelength of 486.0 nm. What can we conclude?

The star is moving toward us.

All of the following statements about the Sun's corona are true. Which one explains why it is a source of X rays?

The temperature of the corona's gas is some 1 to 2 million Kelvin.

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?

The thin air on mountaintops makes the glass in telescope mirrors less susceptible to warping.

Studying a spectrum from a star can tell us a lot. All of the following statements are true except one. Which statement is not true?

The total amount of light in the spectrum tells us the star's radius.

The planet Neptune is blue in color. How would you expect the spectrum of visible light from Neptune to be different from the visible-light spectrum of the Sun?

The two spectra would have similar shapes, except Neptune's spectrum would be missing a big chunk of the red light that is present in the Sun's spectrum.

Which of the following best describes the development of astronomical telescopes over the past 65 years?

The world's most powerful telescope remained the same for most of this period, but in the past 20 years many new and more powerful telescopes have been built.

Which planet listed below has the most extreme seasons?

Uranus

The Chandra X-ray Observatory must operate in space because

X rays do not penetrate Earth's atmosphere.

Which of the following statements about X rays and radio waves is not true?

X rays travel through space faster than radio waves.

No object produces a perfect thermal radiation spectrum, but many objects produce close approximations. Which of the following would not produce a close approximation to a thermal radiation spectrum?

a hot, thin (low-density, nearly transparent) gas

Suppose you have a camera attached to a telescope, and you want to record an image of a very faint galaxy. Which of the following will help the most?

a lot of pixels and a long exposure time

Compared to the distance between Earth and Mars, the distance between Jupiter and Saturn is ______.

much larger

Mars has two moons that are most similar in character to:

small asteroids

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

turbulence in the Earth's atmosphere

Gamma rays have a very small ______.

wavelength