Module 2 ASTR 100

For each question, answer whether it describes: Summer Solstice, Winter Solstice, Autumnal Equinox, Vernal Equinox. Some will have two answers. Sun is highest in sky when it crosses meridian First day of winter in Northern Hemisphere Occurs around June 21 in Northern Hemisphere Start of fall in Northern Hemisphere 12 hours of daylight everywhere on Earth.

Summer Solstice = June 21st (start of summer), longest day in the northern hemisphere, Sun highest in the sky in the northern hemisphere. Winter Solstice = December 21st (start of Winter), shortest day of the year in the northern hemisphere, sun lowest in the sky in the northern hemisphere. Autumnal Equinox = September 21st, 12 hours of daylight Vernal Equinox = March 21st, 12 hours of daylight.

Is the "dark side of the Moon" real? In other words, is there a part of the moon that is never lit? Explain.

The "dark side of the moon" really is just the unknown or unseen side of the moon due to us only being able to observe one side of the moon from the Earth. The other side of the moon gets as much light as the near side of the moon, we just can't see it from Earth.

Explain what it means to be part of the tropics on Earth. Is Los Angeles (Latitude = 34oN) in the Tropics? Explain.

To be a part of the tropics on Earth, you must be in between 23.5 degrees north and 23.5 degrees south. Los Angeles would not be in the tropics because it is not within the tropics line specified.

T/F: We always see the same side of the Moon from the Earth.

True: This is true because the moon is on a synchronous rotation.

What do the terms waxing and waning mean?

Waxing means the amount of space being illuminated is getting bigger, it is growing in size and brilliance, while waning means that space that is illuminated that we can see is getting smaller.

When the North Pole is tilted towards the Sun, describe the seasons in the Northern and Southern Hemisphere. What are the seasons like when the South Pole is pointed towards the Sun?

When the north pole is tilted towards the sun it is Summer in the Northern Hemisphere and winter in the Southern hemisphere and it is the opposite when the southern pole is pointed towards the sun.

Does the moon rotate? Explain why or why not. What is synchronous rotation?

Yes the moon does rotate. The moon rotates on its axis one per revolution around the Earth in its synchronous rotation. This means that the moons rotation is in sync with the Earth's, so we are always seeing one side of the moon.

Which of these statements is true? a) If the Earth did not orbit the Sun, stars would rise at the same time every day. b) Leap years are necessary because a year is about 365.24 days and not exactly 365 days. c) It takes approximately 2 weeks for the moon to go from new moon to full moon. d) All of the above.

d) All of the above.

The Sun is setting at this moment. It is at the horizon exactly west. Which of the following could be the altitude and azimuth of the Sun? a) Altitude = 90o, Azimuth = 90o b) Altitude = 90o, Azimuth = 270o c) Altitude = 270o, Azimuth = 0o d) Altitude = 0o, Azimuth = 90o e) Altitude = 0o, Azimuth = 270o

e) Altitude = 0o, Azimuth = 270o

Imagine that the Moon is a waning gibbous. Which of the following is true? a) More of the moon will appear lit tomorrow than today. b) The Moon will be visible in the sky at sunset. c) Less than half of the Moon will appear lit. d) It has been a full moon within the last week. e) All of the above.

d) It has been a full moon within the last week.

Why is it warmer during the summer than during the winter? a) The earth rotates faster during the summer. b) The center of the earth is closer to the Sun in the summer. c)The Sun puts out more light during the summer. d) Sunlight hits us more directly in the summer.

d) Sunlight hits us more directly in the summer.

Which of these statements is NOT true about the Moon? a) The Moon has synchronous rotation. b) The same side of the Moon always faces the Earth. c) The Moon rotates on its axis. d) There is a side of the Moon that never receives sunlight (ie. a dark side of the moon).

d) There is a side of the Moon that never receives sunlight (ie. a dark side of the moon).

A star with RA = 5hr will transit at 6pm today. What time will a star with RA = 8hr transit today? a) 3pm b) 5pm c) 6pm d) 7pm e) 9pm

e) 9pm

How do stars appear to move if you are at the North Pole? What is different at the South Pole?

At the North Pole you are standing where the Earth's axis of rotation intersects with the surface, kind of like standing on a rotating turntable or wheel. The stars in the North pole appear to move counter clockwise and never set and they move clockwise and never set in the south pole. It's the daily motion of the Earth spinning on its access.

What are circumpolar stars? Are there circumpolar stars if you are at the equator? Explain. What about if you are at the North or South Pole? Explain.

Circumpolar stars are stars that can always be seen above the horizon by the observer. There are no circumpolar stars if you are observing from the equator because you are observing from in between the north and south celestial poles. You can theoretically see the whole heavens!

What point on the celestial sphere is directly above: Earth's North Pole Earth's South Pole Earth's Equator

Earth's North Pole = North celestial pole Earth's South Pole = South celestial pole Earth's Equator = Celestial equator

What does the name equinox mean? Explain why the name equinox makes sense.

Equinox means "equal night". This definition makes sense because there is 12 hours (half a day) of daylight on equinoxes.

T/F: The Sun appears to go directly overhead every day. Explain.

False: It appears this way because the Earth has rotated to the point in the day where you are directly facing the sun

T/F: The north celestial pole does not move in the sky each day.

False: The north celestial pole moves over time and the north celestial pole only moves if you were to move latitudes. The north celestial pole is higher above the horizon in the north vs the southern parts of the northern hemisphere.

Describe what would happen to seasons on Earth if the Earth's rotation axis had no tilt.

If the Earth's rotation axis had no tilt there would be no such thing as seasons. The sun would live on the celestial equator, and follow the same path each day from sunset to sunrise, and the days and nights would be exactly 12 hours long everywhere.

Explain why it is always cold near the North and South Pole. Why are regions near the Poles sometimes called the "Land of the Midnight Sun"?

It is always cold in these regions because the sun never rises very high in the sky and so the sunlight is never very direct in these areas. These regions are sometimes called "the lands of the midnight sun" because they have a full 24 hours of sunlight during the summer time.

Explain why leap years are necessary to keep our Gregorian calendar lined up with the tropical year.

Leap years are necessary because the tropical year measures time from one equinox to another, and that math calculates out to 365.24 days in a year. The leap year makes up that extra day and allows our calendars to stay on track and in sync.

What is local noon? Describe the altitude of the Sun at local noon.

Local noon is the highest point the sun will reach on any given day. The sun at local noon doesn't reach the zenith point unless you are on a specific part of the Earth, and the altitude of local noon changes throughout the year as the days get shorter and longer.

What is Polaris? Describe how Polaris can be used in the Northern Hemisphere to find your latitude.

Polaris is the current North star. The North star's altitude is almost equal to your latitude on Earth, and with it's help you can determine east, west and South which will help determine which direction to travel.

What is the difference between revolve and rotate?

Rotating means an object that spins on an axis through its center and revolve means one object orbits another. (The Earth rotates on its axis while revolving around the sun)

Will the north celestial pole always be near Polaris? Explain

The North Celestial pole will not always be near Polaris because of the Earth's precession cycle, which lasts about 26,000 years. It will be near Polaris again in the future, but not for a very long time, and we will see several variations of North Stars over time.

Explain why seasons on the Earth cannot be due to the different distances of the Earth from the Sun as it orbits. There are 2 reasons given in the book.

The earth is tilted on its axis, so when the North Pole is tilted towards the sun, there are more than 12 hours of daylight in the day in the northern hemisphere. When the south pole is tilted towards the sun, there are less than 12 hours of daylight in the northern hemisphere. During the summer, the affected hemisphere is more perpendicular with the sun, so absorbing more energy in the atmosphere.

When is the Sun highest in the sky - summer or winter? Explain how the altitude of the Sun can cause temperature differences?

The sun is higher in the sky in the summer time than in the winter time. The altitude of the sun in the summer means that the sun's energy is more directly hitting the Earth, which causes the Earth to be warmer

Define the following terms: Zenith, Horizon, Meridian, Altitude

Zenith: The point in the sky directly above wherever you are. Horizon: The line that separates the Earth from the sky. Meridian: The imaginary line separating north and south. Altitude: The angle above the horizon.

Betelgeuse rises at 4:20pm today. What time will it rise one month from now? a) 2:20pm b) 4:16pm c) 4:20pm d) 4:24pm e) 6:20pm

a) 2:20pm

As an object gets closer to the Earth, its angular size: a) Increases b) Decreases c) Stays the same

a) Increases

Which of these is true about the day? a) Local noon is defined as the time each day when the Sun reaches its highest point. b) A solar day is shorter than a sidereal day. c) A sidereal day is defined as the time between two transits of the Moon. d) All of the above.

a) Local noon is defined as the time each day when the Sun reaches its highest point.

For each phase, describe how much of the Moon appears lit: a) New b) Crescent c) Quarter d) Gibbous e) Full

a) New The moon appears only in the daytime, but only the far side is lit. b) Crescent The moon is illuminated in what looks like a crescent shape, like a croissant. only a sliver of light can be seen at this time. c) Quarter The moon looks like it is half illuminated, split down the middle. d) Gibbous Is more than half illuminated e) Full The moon is completely illuminated.

On the summer solstice, a) The Sun is the highest it will get in the sky in the Northern Hemisphere. b) Days are the shortest they will be in the Northern Hemisphere. c) The Sun rises exactly to the East. d) All of the above.

a) The Sun is the highest it will get in the sky in the Northern Hemisphere.

Which of the following statements is true? a) The celestial equator is directly above Earth's north pole. b) At the North Pole stars appear to follow circular paths around the sky and always have the same altitude. c) At the equator there are more than 1000 circumpolar stars visible to the naked eye. d) The Earth rotates around the Sun (the word rotate is important here). e) All of the above.

b) At the North Pole stars appear to follow circular paths around the sky and always have the same altitude.

Which of the following statements is true? a) Local noon occurs at the same time for an observer in Seattle and 100 miles east of Seattle. b) If the Earth did not orbit the Sun, then Los Angeles (or any other place on Earth) would not experience any changes in seasons (it would always be the same season). c) If the Earth had a very small tilt to its rotation axis, then there would be more extreme seasons. d) All of the above.

b) If the Earth did not orbit the Sun, then Los Angeles (or any other place on Earth) would not experience any changes in seasons (it would always be the same season).

Which of the following is true about precession? a) Because of precession, astrological dates always match up perfectly with the dates the Sun is in a constellation. b) Precession means that Polaris will not always be the North Star. c) Precession is the quick wobbling of the Earth's rotation axis -a full wobble only takes about 3 years. d) All of the above.

b) Precession means that Polaris will not always be the North Star.

Which of these stars will be above the horizon the longest in Seattle? a) Star with a declination of -25. b) Star with a declination of +60 c) Star with a declination of 0 d) Star with a declination of +47

b) Star with a declination of +60 All stars are above the horizon the same amount of time in Seattle

Which of these statements is true? a) Areas near the North Pole are sometimes called the "Land of the Midnight Sun" because the Sun is in the sky at midnight all year. b) The name "equinox" is appropriate because everywhere on the Earth night and day are the same lengths on the equinoxes. c) It is always cold near the South Pole because the South Pole is at a very high elevation. d) If you are located in the Tropics then the Sun will be directly overhead every day.

b) The name "equinox" is appropriate because everywhere on the Earth night and day are the same lengths on the equinoxes.

Which of these statements is true? a) If the Moon is visible in the sky at sunset, then it must be a crescent moon. b) The new moon is in the sky during the daytime. c) The Moon rises 4 minutes earlier each day. d) If the moon is waxing, then less and less of the moon is visible each day. e) All of the above.

b) The new moon is in the sky during the daytime.

Which of the following best describes the reason for the phases of the moon? a) Different amounts of Earth's shadow falls on the moon as it orbits the Earth. b) We see different amounts of the lit side of the moon as it orbits the Earth. c) The Moon orbits the Sun; we see different phases depending on the distance to the Sun. d) All of the above

b) We see different amounts of the lit side of the moon as it orbits the Earth.

If it is summer in the Northern Hemisphere, what season is it in the Southern Hemisphere? a) Summer b) Winter c) Fall d) Spring

b) Winter

What is the declination for the celestial equator? a) -90 b)0 c) +34 d) +90

b)0

Which of these is NOT true about the year and the signs of the zodiac? a) A year is the time it takes for the Earth to orbit the Sun once. b) During the year the Sun appears to pass through 13 constellations on the celestial sphere. c) If the Sun is in the constellation Virgo today, then Virgo will be high in the sky at midnight today. d) The dates for the zodiac signs and the dates the sun is actually in each constellation are different by about one month.

c) If the Sun is in the constellation Virgo today, then Virgo will be high in the sky at midnight today.

Imagine that it is a full moon as seen from Earth and there are no eclipses. If a person living on the Moon is looking at the Earth how much of the Earth will she see lit? a) The entire Earth facing her will seem lit. b) She will see half of the Earth facing her lit. c) None of the Earth facing her will seem lit. d) Trick question --- the Earth will NEVER seem lit from the moon no matter what phase of the Moon it is.

c) None of the Earth facing her will seem lit.

Which of the following statements is NOT true about angular size? a) Angular size is the angle in the sky taken up by an object. b) Angular size is important for astronomy because it is not always easy to measure the physical size of an object. c) The Sun has a much larger angular size than the Moon. d) When the moon is close to the horizon, its angular size is the same as when the moon is high in the sky.

c) The Sun has a much larger angular size than the Moon.

If the Earth did not orbit the Sun, a) The Sun would always appear to be in the same constellation. b) The same stars would be in the sky each night. c) A star would rise at the same time each day. d) All of the above.

d) All of the above.

Topocentric coordinates for a star: a) will be different for observers at two different places on Earth. b) will change between now and two hours from now. c) are altitude and azimuth. d) All of the above.

d) All of the above.

Which of these is true about Polaris? a) Polaris is directly overhead if you are at the North Pole. b) Polaris will be at an altitude of 47 degrees in Seattle (Latitude = 47 degrees) c) Polaris has a declination of +90 degrees. d)All of the above.

d) All of the above.