Question 1

What is the term for the point on the celestial sphere directly above an observer,no matter where on the Earth the observer is located?

Accepted Answer

The point on the celestial sphere directly above an observer is called zenith. It is located at the top of the observer's local sky and changes as the observer's position on Earth changes. The north and south celestial poles are vertical points above the Earth's North and South poles, respectively, and the nadir is the point directly beneath an observer.

Question 2

If the apparent visual magnitude of a star is 7.3,what does this tell us about the brightness of the star?

Accepted Answer

The apparent visual magnitude of 7.3 indicates that the star is relatively faint and cannot be seen with the unaided eye. Magnitudes are measured on a logarithmic scale, where every increase in 1 magnitude is a decrease in brightness by a factor of 2.512. So, a star with an apparent visual magnitude of 1 is 100 times brighter than a star with an apparent visual magnitude of 6, and a difference of 2 magnitudes represents a brightness ratio of 6.3 (2.512 × 2.512). Therefore, a star with an apparent visual magnitude of 7.3 is much fainter than stars that are visible to the naked eye.

Question 3

Seen from Winnipeg (latitude 50 degrees North),where is the star Polaris in the sky?

Accepted Answer

Polaris is located approximately at the North Celestial Pole, and its altitude above the horizon is roughly equal to the observer's latitude. Since Winnipeg is at 50 degrees North, Polaris would be about 50 degrees above the horizon.

Question 4

Which of the following is equivalent to one-3,600ᵗʰ of a degree?

Accepted Answer

One-3,600th of a degree is the same as one second of arc. One degree is divided into 60 minutes, and each minute is divided into 60 seconds. Therefore, one second of arc is the smallest division of a degree.

Question 5

The star Vega has an apparent visual magnitude of 0.03 and the star HR 4374 has an apparent visual magnitude of 4.87.It has been determined that both stars are at the same distance from the Earth.What does this information tell us about the two stars?

Accepted Answer

Apparent visual magnitude is related to the energy output of a star. A lower magnitude indicates a brighter star, which means it is producing more energy per second. Since Vega has a lower magnitude than HR 4374 despite being at the same distance from Earth, it must be producing more energy per second. Therefore, option C is correct. Option A is incorrect because the combined magnitude of two stars cannot be simply added together. Option B is incorrect because we do not know the energy output of HR 4374. Option D is incorrect because Vega actually has a lower magnitude (and therefore appears brighter) than HR 4374.

Question 6

Where in the sky would an observer at the Earth's equator see the celestial equator?

Accepted Answer

The answer of Where in the sky would an observer...

Question 7

What is the celestial equator?

Accepted Answer

The celestial equator is the imaginary line in the sky that represents the Earth's equator projected into space, dividing the north and south celestial hemispheres.

Question 8

What causes the precession of the Earth's rotation axis?

Accepted Answer

The force of gravity from the Sun and Moon on the Earth's equatorial bulge causes a torque on the Earth, which leads to a gradual shift in the orientation of its rotation axis. This is known as precession.

Question 9

For an observer in New Delhi,India,at a latitude of 28° North,what is the angle between the northern horizon and the north celestial pole?

Accepted Answer

The angle between the northern horizon and the north celestial pole is equal to the latitude of the observer. In this case, the observer is in New Delhi, India, at a latitude of 28° North, so the angle is 28°.

Question 10

Which of the following best describes the Big Dipper?

Accepted Answer

The Big Dipper is an asterism, which is a recognizable pattern of stars within a constellation. The Big Dipper is part of the constellation Ursa Major, also known as the Great Bear. It is distinct from the Seven Sisters, which is another cluster of stars also known as the Pleiades.

Question 11

Why are Venus and Mercury often called "morning star" and "evening star"?

Accepted Answer

Venus and Mercury are often called "morning star" and "evening star" because they are only visible just before sunrise or just after sunset. This is due to their orbits being closer to the Sun than Earth's orbit, causing them to always appear near the Sun in the sky.

Question 12

For an observer in Valdivia,Chile,at a latitude of 39° South,what is the angle between the southern horizon and the south celestial pole?

Accepted Answer

The angle between the southern horizon and the south celestial pole is equal to the latitude of the observer. In this case, the observer is at a latitude of 39° South, so the angle is 39°.

Question 13

For an observer in Lusaka,Zambia,at a latitude of 16° South,what is the angle between the southern horizon and the south celestial pole?

Accepted Answer

The angle between the southern horizon and the south celestial pole is equal to the observer's latitude, which is 16° South in this case.

Question 14

Where is an observer's nadir?

Accepted Answer

Nadir is the point directly opposite the zenith of the observer, which is the point directly below the observer. Therefore, it is located at the point directly opposite the observer's zenith.

Question 15

For an observer in Pond Inlet,Nunavut,at a latitude of 73° North,what is the angle between the northern horizon and the north celestial pole?

Accepted Answer

The angle between the northern horizon and the north celestial pole is equal to the observer's latitude, which is 73° North in this case.

Question 16

What languages do the standard constellation names come from?

Accepted Answer

The standard constellation names come mostly from Greek and Latin.

Question 17

What language is the source of most star names,such as Aldebaran and Betelgeuse?

Accepted Answer

Most star names have originated from Arabic, as astronomers in the Islamic Golden Age were the ones who extensively studied and documented the skies. However, some of these Arabic names have been derived from earlier Greek or Latin names. Italian, on the other hand, has had a significant impact on astronomy, but not on the naming of stars.

Question 18

What is the purpose of the magnitude scale?

Accepted Answer

The magnitude scale is used to measure the apparent brightness of a celestial object. It is a logarithmic scale, where a difference of 5 magnitudes corresponds to a difference of 100 times in brightness.

Question 19

An observer in the northern hemisphere watches the sky for several hours.Due to the motion of the Earth,this observer notices that the stars near the north celestial pole appear to move.What pattern does this apparent movement follow?

Accepted Answer

Stars near the north celestial pole appear to rotate counter-clockwise around the celestial pole due to the Earth's rotation on its axis. This rotation is what causes the apparent movement of stars in the night sky.

Question 20

What aspect of an object depends on both the size of the object and the distance to the object?

Accepted Answer

Angular diameter depends on both the size of the object and the distance to the object, as it is the angle formed by lines extending from the observer to the edges of the object.

Quiz 2: User's Guide to the Sky