Astronomy Final

Which of the illustrations A, B, C, D represents the apparent motion of the sky as seen by an observer at Earth's equator? The thick black line is the horizon. question.jpg

B

An object that rises due East will set due West about ________ hours later.

about 12 hours

is how high an object is above the horizon, and ______ is the object's angular distance from due North, going clockwise (due East=90 degrees, due South=180 degrees, etc)

altitude azimuth

____of the North Celestial Pole (NCP) is equal to the observer's____

altitude latitude

___of the North Celestial Pole (NCP) is equal to the observer's___

altitude latitude

On the day of the vernal equinox, the Sun transits your meridian at an altitude of 12. What is your latitude?

78

Sirius crosses the meridian of Memphis, TN six hours after crossing the meridian of Greenwich, England. From this, we know that the longitude of Memphis, TN is:

90 Degrees West

If it is 7PM in Los Angeles (latitude 34N, Longitude 119W) what time is it in New York (latitude 41N, longitude 74W)?

10 pm

You are observing the sky from a northern latitude 10, and you wish to observe a star whose declination is a positive 30 degrees. When it passes your meridian, what is its altitude?

110

If you observe that Polaris is 20 degrees above your horizon to the north, where are you? You are at (write a number) degrees (write N or write S) (latitude, longitude - write the word that is correct).

20 N Latitude

Can an observer living at the equator ever see the sun rise 30 degrees south of East? (yes or no) What is the furthest the sun will rise north of east for this observer? (give a number)

23.5

An object that rises at azimuth 80 will set at azimuth ________________

280

Given that the declination of the Sun is -10.9, what is the highest altitude of the Sun on from 47.5 degrees of latitude?

31.6

On the US Mainland (contiguous 48 states), how many time zones are there? (Answer in blank 1) Name (some of) these time zones (in blanks 2 through 5).

4 central time zone eastern time zone pacific time zone mountain time zone

You are outside, and you notice that the Celestial Equator is crossing your meridian at an altitude of 42 degrees. What is your latitude?

48

If you are observing the sky from latitude 45, and you wish to observe a star whose declination is 10 degrees, when it passes your meridian, what is its altitude?

55

Ames is located at a longitude close to 90 degrees W. You want to call a friend who lives in England, near Greenwich (0 degrees E/W). Ignoring such possible complications as daylight savings time, if it is noon here what time is it for your friend? Possibly useful information: 360 degrees = 24 hours; 15 degrees = 1 hour; 1 degree = 4 minutes

6 PM

If the noon Sun on March 21 is 30 degrees above your horizon to the South, where on Earth are you?

60 degrees N latitude

For an observer at 30°N latitude, at what altitude will the Winter Solstice Sun transit his/her meridian?

60° - 23.5° = 36.5°

Above which of these latitudes must a person live in order to have a full day (24 hours) where the sun does not rise?

66.5 deg N

Reykjavik is located at latitude 64N on the west coast of Iceland. Ames, Iowa is at 42N near the center of the North American continent. Which of the following statements is true about these two locations?

Although Reykjavik is farther north, it is in the ocean and near the Gulf Stream, so its winters are not much colder than the winters in Ames.

In the days of the early explorers, why was it challenging to accurately determine longitude?

Clocks couldn't keep accurate time on ships, so comparing local time to time back home was difficult

Which of the following descriptions is WRONG? -Solar time is time according to a sundial. -Daylight Savings Time gives us more hours of sunlight and fewer hours of darkness. -Mean solar time agrees with a sundial on the average, but may be different by as much as 15 minutes either way at some times of the year. -Standard time is mean solar time for a special meridian, such as 90 degrees W for Central Time. -A sidereal day is four minutes shorter than a solar day.

Daylight Savings Time gives us more hours of sunlight and fewer hours of darkness.

In this figure, the Earth's axis of rotation is the double line, and two observers at different latitudes are shown with their horizons indicated. Which of the following correctly describes how much of the sky these observers can see?

For both observers, there are some circumpolar constellations. Observer A, located closer to the North Pole, has more circumpolar constellations and, over the course of a year, can observe fewer stars than Observer B. Observer B, being closer to the horizon, sees more stars over the course of a year but has fewer circumpolar constellations. Both observers can observe constellations near the celestial equator and neither of them can see the South Celestial Pole.

You observe a very bright star due South and about 3 fists (30 degrees) above the horizon. You send an email to an astronomer friend asking what it is. Do you need to tell the astronomer what time you made this observation?

Yes, because as the Earth turns the objects in the sky appear to move from East to West

You observe a very bright star due South and about 3 fists (30 degrees) above the horizon. You send an email to an astronomer friend asking what it is. Do you need to tell the astronomer what time you made this observation?

Yes, because as the Earth turns the objects in the sky appear to move from East to West.

Which of the following answers are true? Mark the true ones and only the true ones.

You can get to the latitude of an island by sailing until its star passes through your zenith - its star is one where the declination of the star is equal to the desired latitude.

Although the Winter Solstice occurs in December, it is usually colder here in January/February than in December. Why is that?

It takes time for the ground to cool.

You observe several a faint object in the sky with the same angular size as the Moon. From your observations, you can conclude that the object is ___

It's impossible to tell without also knowing how far away the faint object is.

A star with declination +30 degrees is observed at azimuth 180 and altitude 45 degrees. From what LONGITUDE are you observing this star?

Longitude cannot be determined from the information given

Can an observer who lives in Australia see the North Star?

No, because the North Star is only visible to inhabitants of the northern hemisphere

The Sun rises and sets; the Moon rises and sets. As seen from a location on Earth that is arbitrary and in no way special, do all stars also rise and set, or do some stars stay in the sky all the time, or do all stars stay in the same place in the sky and neither rise nor set?

No, from most places there are some stars (like the North Star from Ames) that stay in the sky all the time, while other stars and constellations (like Orion) rise and set.

The star trails in D show what an observer would see if he or she was at or very near the Earth's [x1].

North Pole

he star trails in D show what an observer would see if he or she was at or very near the Earth's [x1]. (lines going left to right)

North Pole

Which of the following is a valid way to determine your longitude? Note: Valid here means both correct and complete; an answer that tells only part of what you would need to do is not correct.

You can measure the time the Sun crosses your meridian and compare that with the time at home; the longitude difference is found from (time where you are) - (time at home)+(time at home)-(time in Greenwich).

Why does the Earth have seasons, with (for Ames) the warmest weather in June, July, and August?

The tilt of the Earth makes the days longer in summer, and the sunlight spread out more across the ground in the winter.

There are many ways to measure your latitude and not so many to measure your longitude. Of the following procedures, which one measures longitude?

You determine the time when the Sun crosses the meridian and relate that to the time at home

If you travel from East to West, say New York to Los Angeles, then you set your watch by one hour per time zone. When you travel from West to East, say New York to London, you set your watch by one hour per time zone. If you cross the international date line traveling westward, you will need to one day, or 24 hours, while if you travel eastward across the IDL you need to one day

back ahead add subtract

If you travel from East to West, say New York to Los Angeles, then you set your watch back by one hour per time zone. When you travel from West to East, say New York to London, you set your watch ahead by one hour per time zone. If you cross the international date line traveling westward, you will need to add one day, or 24 hours, while if you travel eastward across the IDL you need to subtract one day.

back ahead add subtract

When you travel westward, you have to shift your watch ___________ (back or earlier, forward or later) each time you pass a time zone boundary. On the same trip, when you pass the international date line, you have to shift the date __________ (forward, backward) by one day.

back; forward

Question: Why is it warmer in the summer than in the winter? One of the following four answers is WRONG. Which one is it?

in the summer we are closer to the sun than in winter

When it is winter in Iowa what is the season in New Zealand?

it is summer in New Zealand

The navigational technique where you keep track of your heading and your speed and use that to figure out where you are is called [Blank1].

dead reckoning

If the tilt of the Earth's axis were greater, the Sun's ____________ would vary by more than it does.

declination

Which of the following would be dramatically different if the tilt of the Earth was doubled?

declination of the sun at the solstices

The apparent path of the sun against the background stars over the course of the year is the _________________. [Blank1]

ecliptic

The zero point for latitude is the while the starting point for longitude is the

equator prime meridian

True or False: a star compass (assuming that the rising azimuth = 90 + declination) is an accurate tool for travelers anywhere in the world

false

How often does the Sun pass through your zenith (= the sky directly overhead, 90 degrees from the horizon) when you are in Ames?

never from Ames

For an observer in the northern hemisphere, the sun rises (north/south) of east in the summer, and it rises (north/south) of east in the winter.

north south

The sidereal time for an observer is the same as the ________ of an object on the observer's meridian.

right ascension

The expansion of the railroad from coast to coast brought about the development of _______________, where the same mean solar time is used for a range in longitude 15 degrees wide.

time zones

True or False: For an observer at the North Pole, there are times during the year where the sun does not set for days.

true

True or False: For an observer who lives at latitude 70°S there are days when the Sun never gets above the horizon and other days when it never goes below the horizon.

true

Which is NOT a technique to measure your latitude?

using dead reckoning

The point directly above an observer's head is called the____. The North Point, the South Point, and the Zenith all are on the observer's ___.

zenith meridian