AST Unit I

Two stars that are in the same constellation: 1. must both be part of the same cluster of stars in space. 2. must both have been discovered at about the same time. 3. may actually be very far away from each other.

What is the celestial sphere? 1. The celestial sphere is a representation of how the entire sky looks as seen from Earth. 2. It represents a belief in an Earth-centered universe, and hence is no longer considered to have any use. 3. The celestial sphere is a model of how the stars are arranged in the sky relative to our Sun, which is in the middle of the sphere. 4. The celestial sphere is a model that shows the true locations in space of the Sun and a few thousand of the nearest stars.

What do we mean when we talk about the Milky Way in our sky? 1. the spiral-shaped galaxy in which we live 2. the patchy band of light that outlines the plane of the Milky Way Galaxy as seen from Earth 3. the bright stars of the constellations that lie along the ecliptic in our sky 4. the whitish patch of light we see when we look toward the center of the Milky Way Galaxy

Which of the following correctly describes the meridian in your local sky? 1. a half-circle extending from your horizon due east, through the north celestial pole, to your horizon due west 2. a half-circle extending from your horizon due east, through your zenith, to your horizon due west 3. the point directly over your head 4. a half-circle extending from your horizon due north, through your zenith, to your horizon due south

The point directly over your head is called ________. 1. the north celestial pole 2. the meridian 3. the zenith 4. the North Star

The North Celestial Pole is 35.0 ∘ above your northern horizon. This tells you that: 1. you are at latitude 35.0 ∘ N. 2. you are at longitude 35.0 ∘ E. 3. it is the winter solstice.

Which of the following statements about the celestial sphere is not true? 1. The "celestial sphere" is another name for our universe. 2. The Earth is placed at the center of the celestial sphere. 3. The celestial sphere does not exist physically. 4. When we look in the sky, the stars all appear to be located on the celestial sphere.

When traveling north from the United States into Canada, you'll see the North Star (Polaris) getting ________. 1. brighter 2. higher in the sky 3. lower in the sky 4. dimmer

Suppose you use the Southern Cross to determine that the south celestial pole appears 40 degrees above your horizon. Then you must be located at ________. 1. latitude 40 degrees south 2. longitude 40 degrees 3. latitude 50 degrees south 4. latitude 40 degrees north

Suppose you are facing north and you see the Big Dipper close to your northern horizon, with Polaris (and the Little Dipper) above it. Where will you see the Big Dipper in six hours? 1. still in the same place, below Polaris 2. directly above Polaris 3. to the right of Polaris; that is, 90 degrees counterclockwise from its current position 4. to the left of Polaris; that is, 90 degrees clockwise from its current position

RXJ1800, a galaxy, lies very near in the sky to the bright star Vega. What is the best explanation for them appearing close together? 1. Their random motions have caused RXJ1800 and Vega to drift to within a few light-years of each other. 2. Vega must have recently formed in RXJ1800 and been ejected. 3. They coincidentally lie along the same line of sight. 4. Vega orbits the center of mass of RXJ1800.

What do astronomers mean by a constellation? 1. A constellation is any random grouping of stars in the sky. 2. A constellation is a region in the sky as seen from Earth. 3. A constellation is a group of stars related through an ancient story. 4. A constellation is a group of stars that are all located in about the same place in space.

Stars that are visible in the local sky on any clear night of the year, at any time of the night, are called ________. 1. circumpolar 2. seasonal 3. bright 4. celestial

We describe a location on Earth's surface by stating its ________. 1. latitude and direction 2. latitude and longitude 3. meridian and longitude 4. altitude and direction (or azimuth)

If you are located in the Northern Hemisphere, which of the following correctly describes a relationship between the sky and your location? 1. The altitude of the north celestial pole equals your latitude. 2. The altitude of the north celestial pole equals your longitude. 3. The longitude of the north celestial pole is circumpolar, and therefore crosses your zenith at the meridian. 4. The altitude of the celestial equator equals your latitude.

What is a circumpolar star? 1. a star that is close to the north celestial pole 2. a star that makes a daily circle around the celestial sphere 3. a star that always remains above your horizon 4. a star that is visible from the Arctic or Antarctic circles 5. a star that is close to the south celestial pole

What makes the North Star, Polaris, special? 1. It appears very near the north celestial pole. 2. It is the brightest star in the sky. 3. It is the star straight overhead. 4. It is the star directly on your northern horizon. 5. It can be used to determine your longitude on Earth.

Which of the following statements about circumpolar stars is true at all latitudes? 1. You cannot see them from the Southern Hemisphere. 2. They always remain above your horizon. 3. They make relatively small circles, traveling clockwise around the north celestial pole. 4. They are the stars close to the north celestial pole. 5. Like all other stars, they rise in the east and set in the west.

By locating the north celestial pole (NCP) in the sky, how can you determine your latitude? 1. The altitude of the NCP is the same as your latitude. 2. The direction of the NCP is the same as your latitude. 3. The altitude of the NCP is the same as your distance from the North Pole. 4. The altitude of the NCP is your angular distance from the North Pole. 5. The direction of the NCP is the angular distance from the North Pole.

During the time that a planet is in its period of apparent retrograde motion, _________. 1. the planet moves backwards (clockwise as viewed from above Earth's north pole) in its orbit of the Sun 2. the planet appears to rise in the west and set in the east, rather than the usual rising in the east and setting in the west 3. over many days or weeks, the planet moves westward relative to the stars, rather than the usual eastward relative to the stars 4. the planet is getting closer to the Sun in its orbit

When we see Saturn going through a period of apparent retrograde motion, it means 1. Saturn and Earth must be on opposite sides of the Sun. 2. Earth is passing Saturn in its orbit, with both planets on the same side of the Sun. 3. Saturn is temporarily moving backward in its orbit of the Sun.

What is really happening in space during the periods when we see Mars going through apparent retrograde motion? 1. Earth and Mars are moving in opposite directions around the Sun. 2. Mars and the Sun both appear to be in the same constellation as viewed from Earth. 3. Earth is passing by Mars in its orbit around the Sun. 4. Mars is moving along its orbit in the opposite direction from the way it usually moves.

During the period each year when we see Mars undergoing apparent retrograde motion in our sky, what is really going on in space? 1. Earth is catching up with and passing by Mars in their respective orbits. 2. Earth and Mars are on opposite sides of the Sun. 3. Mars is moving around the Sun in the opposite direction from which Earth is moving around the Sun. 4. Earth and Mars are getting closer together.

What happens during the apparent retrograde motion of a planet? 1. The planet moves through constellations that are not part of the zodiac. 2. The planet appears to move westward with respect to the stars over a period of many nights. 3. The planet moves backward through the sky. 4. The planet rises in the west and sets in the east. 5. The planet moves backward in its orbit around the Sun.

What causes the apparent retrograde motion of the planets? 1. As Earth passes another planet, the other planet appears to move backward with respect to the background stars, but the planet's motion does not really change. 2. Apparent retrograde motion is an illusion created by turbulence in Earth's atmosphere. 3. As Earth passes another planet, its gravitational pull slows down the other planet so that it appears to be traveling backward. 4. The other planets never really appear to move backward; the background stars shift due to Earth's revolution around the Sun. 5. When planets are farther from the Sun, they move slower than when they are nearer the Sun; it is during this slower period that they appear to move backwards.

Which of the following never goes in retrograde motion? 1. the Sun 2. Jupiter 3. Venus 4. Saturn 5. Mars

What is the ecliptic? 1. a half-circle extending from your horizon due north, through your zenith, to your horizon due south 2. the path the Sun appears to trace around the celestial sphere each year 3. the Sun's daily path from east to west in our sky 4. the path traced by the Moon's shadow on Earth during a solar eclipse

In any particular place on Earth, certain constellations are visible in the evening only at certain times of the year because ________. 1. on any particular night, we can only see stars that are directly opposite (180 degrees away from) the Sun in the sky 2. some constellations are circumpolar 3. during some times of year, some constellations drop below the southern horizon 4. our evening view of space depends on where Earth is located in its orbit around the Sun

The Sun's path, as viewed from the equator, is highest in the sky on ________. 1. the day when Earth is closest to the Sun 2. the winter solstice 3. the spring and fall equinoxes 4. the summer solstice

Suppose Earth's axis tilt was significantly greater than its current 23.5 degrees, but Earth's rotation period and orbital period were unchanged. Which statement below would not be true? 1. The length of each season (for example, the number of days from the summer solstice to the fall equinox) would be significantly longer than it is now. 2. Summers and winters would be more severe (for example, hotter and colder, respectively) than they are now. 3. Polaris would not be our North star. 4. The region of Earth where the Sun does not rise on the winter solstice would be larger (extending farther south) than it is now.

If our year were twice as long (that is, if Earth took twice as many days to complete each orbit around the Sun), but Earth's rotation period and axis tilt were unchanged, then ________. 1. the four seasons would each be twice as long as they are now 2. the Earth would not have seasons 3. the cycle of precession would take 13,000 years instead of 26,000 years 4. stars would take twice as long to rise and set

You are standing on Earth's equator. Which way is Polaris, the North star? 1. directly overhead 2. on the northern horizon 3. 30 degrees up, due West 4. The answer depends on whether it's winter or summer. 5. The answer depends on what time of day (or night) it is.

Orion is visible on winter evenings but not summer evenings because of 1. the precession of Earth's axis. 2. the location of Earth in its orbit. 3. baseball on television. 4. interference from the full moon. 5. the tilt of Earth's axis.

As shown in the figure, a solar day requires about an extra 1° of rotation, or a total of about 361° of rotation for Earth. Therefore, a solar day is longer than a sidereal day by about __________. 1. 24 hours 2. 1/360 of 24 hours 3. 1/360 of a minute 4. 1 minute

Which of the following changes would cause the solar day to be shorter (rather than longer) than the sidereal day? 1. Increasing Earth's rotation period 2. Increasing Earth's orbital speed around the Sun 3. Decreasing Earth's rotation period 4. Decreasing Earth's orbital speed around the Sun 5. Reversing the direction of Earth's rotation

Suppose that Earth orbited the Sun 10 times as fast as it actually does but kept the same rotation period it has now. Which of the following would be true? 1. The sidereal day would still be 23 hours, 56 minutes, but the solar day would be a little over 24 1/2 hours. 2. The solar day would be 10 times as long, or about 240 hours. 3. The solar day would actually be a bit shorter than the sidereal day. 4. The solar day would still be 24 hours, but the sidereal day would be a little less than 23 1/2 hours.

The Moon takes about 1 month to orbit Earth (more precisely, about 27 1/3 days), and it travels in the same direction that Earth orbits the Sun. Therefore, during the time it takes the Moon to complete one orbit around Earth, Earth moves __________ around its orbit of the Sun. 1. about 1/12 of the way 2. exactly 27.333∘ 3. about 12∘ 4. about 1∘

Based on your answer to Part E, the time from one new moon to the next must be _________. 1. longer than the Moon's actual orbital period by about 1/12 of the 27-day orbital period 2. longer than the Moon's actual orbital period by about 1/12 of a year 3. shorter than the Moon's actual orbital period by about 1/12 of the 27-day orbital period 4. shorter than the Moon's actual orbital period by about 1/12 of a year

Stars appear to be points on the sky because 1. They are actually points 2. They are far away from us 3. There is a pierced screen surrounding earth 4. Other

Beijing and Philadelphia have about the same latitude but very different longitudes. Therefore, tonight's night sky in these two places: 1. Will look about the same 2. Will have completely different sets of constellations 3. Will have partially different sets of constellations

In the southern hemisphere 1. Stars rise on the west and set on the east 2. Stars rise on the east and set on the west 3. Stars appear to move counterclockwise around the south celestial pole 4. Stars appear to move clockwise around north celestial pole

How long does it take Earth to rotate exactly 360 degrees? 1. Slightly less than 24 hours 2. 24 hours 3. Slightly more than 24 hours 4. One year

In the real universe 1. The celestial sphere resolves around Earth 2. The sun orbits the earth 3. The earth orbits the sun 4. The planets orbit the earth