Question 1

Twice per year, when day and night are equal in length, the Sun is at one of two positions in the sky known as equinoxes. These points are the intersections of which two planes in the sky?

Accepted Answer

The equinoxes occur at the points where the celestial equator (an extension of Earth's equator into space) intersects with the ecliptic (the apparent path of the Sun across the sky over the course of a year). This intersection happens twice a year, leading to days and nights of equal length.

Question 2

If the horizon is considered to be split into northern and southern parts by the east-west line, can the Sun ever rise in the northern part of the sky when viewed from a mid-latitude site in the southern hemisphere?

Accepted Answer

The Sun is always in the northern part of the sky when viewed from a mid-latitude site in the southern hemisphere. This is because the Earth's axis is tilted, and the Southern Hemisphere is tilted away from the Sun for half of the year. During this time, the Sun appears to move in a lower arc across the sky, and it never rises above the northern horizon.

Question 3

For an observer standing at latitude 10° N, how many times during the year will the Sun pass precisely through a point directly overhead, the zenith?

Accepted Answer

The Sun passes directly overhead at a given latitude twice a year between the Tropic of Cancer and the Tropic of Capricorn, which includes the latitude 10° N. This occurs as the Sun moves northward to the Tropic of Cancer and again as it moves southward to the Tropic of Capricorn.

Question 4

When the Sun is at one of the equinoxes,

Accepted Answer

During an equinox, the Sun crosses the celestial equator, leading to nearly equal day and night lengths across the entire Earth, not just at the equator. This happens because the Earth's axis of rotation is not tilted away from or towards the Sun, allowing for an even distribution of sunlight.

Question 5

From Earth's North Pole, how long does the Sun remain above the horizon once it first appears at the beginning of spring?

Accepted Answer

At the North Pole, the Sun rises once at the beginning of spring and sets at the beginning of autumn, staying above the horizon for about six months.

Question 6

The autumnal equinox is the time of the year when the

Accepted Answer

The autumnal equinox occurs when the Sun crosses the equatorial plane from north to south, marking the beginning of autumn in the Northern Hemisphere. This is when day and night are approximately equal in length.

Question 7

If the horizon is considered to be split into northern and southern parts by the east-west line, can the Sun ever rise in the southern part of the sky when viewed from a mid-latitude site in the northern hemisphere?

Accepted Answer

The Sun rises in the southern part of the sky from the autumnal equinox to the vernal equinox, which is approximately half the year.

Question 8

Where on Earth would an observer have to stand for the Sun to pass directly overhead (i.e., pass through zenith) at some time during the year?

Accepted Answer

The Sun passes directly overhead only in the tropics, or within +/- 23.5° of the equator, because this area lies between the Tropic of Cancer and the Tropic of Capricorn, where the Sun's direct rays can reach at different times of the year.

Question 9

The vernal equinox is the time of the year when the

Accepted Answer

The vernal equinox occurs when the Sun crosses the celestial equator moving northward, marking the beginning of spring in the Northern Hemisphere.

Question 10

What is the lowest latitude above which one would see the Sun for a full 24 hours on at least one day per year?

Accepted Answer

The lowest latitude at which one can observe the Sun for a full 24 hours at least once a year is 66.5°, known as the Arctic Circle in the Northern Hemisphere and the Antarctic Circle in the Southern Hemisphere. This phenomenon occurs due to the tilt of the Earth's axis relative to its orbit around the Sun.

Question 11

Which of these statements describing the situation at a mid-latitude site at the time of equinox is correct?

Accepted Answer

During an equinox, which occurs twice a year around March 20th and September 22nd, day and night are approximately equal in length all over the world. This is due to the tilt of the Earth's axis being perpendicular to the Sun's rays.

Question 12

Imagine an observer standing on the South Pole (with the south celestial pole at their zenith) at the time of the vernal equinox. Where would the observer see the Sun all day?

Accepted Answer

At the South Pole during the vernal equinox, the Sun would be on the horizon, marking the transition between six months of daylight and six months of darkness. The equinox occurs when the Sun crosses the celestial equator, making day and night of approximately equal length everywhere on Earth.

Question 13

On the day of the vernal equinox (approximately March 21 each year), which of these conditions holds?

Accepted Answer

On the vernal equinox, which occurs around March 21 each year, day and night are almost exactly 12 hours long everywhere on Earth. This is due to the Sun crossing the celestial equator, moving from the southern to the northern hemisphere, which results in equal amounts of daylight and darkness across the globe.

Question 14

The Arctic Circle, above which the Sun can be seen for a full 24 hours on at least one day of the year, is a line around Earth at what latitude?

Accepted Answer

The Arctic Circle is defined as the latitude 66.5° North of the Equator, where the Sun can be seen for a full 24 hours at least once a year (during the summer solstice) and where the Sun can remain below the horizon for a full 24 hours at least once a year (during the winter solstice).

Question 15

How often does the Sun cross the celestial equator in a given year?

Accepted Answer

The Sun crosses the celestial equator twice a year, marking the equinoxes in March and September, when day and night are approximately equal in length globally.

Question 16

Where would an observer have to be in either the northern or southern hemisphere for the Sun to remain below the horizon for a 24-hour period for at least part of a year?

Accepted Answer

Above about 66.5° latitude in either the northern or southern hemisphere, regions experience polar night, where the Sun remains below the horizon for a 24-hour period during winter months. This phenomenon occurs in areas within the Arctic Circle (above approximately 66.5° North latitude) and the Antarctic Circle (below approximately 66.5° South latitude).

Question 17

The equinoxes are located at the intersections of the

Accepted Answer

Equinoxes occur at the points where the ecliptic (the apparent path of the Sun across the sky) intersects with the celestial equator (the projection of Earth's equator into space). This happens twice a year, marking the beginning of spring and autumn.

Question 18

The vernal equinox is one time of the year when the Sun

Accepted Answer

The vernal equinox occurs when the Sun crosses the celestial equator moving northward, marking the beginning of spring in the Northern Hemisphere.

Question 19

The "Land of the Midnight Sun" is so-named because

Accepted Answer

The "Land of the Midnight Sun" refers to regions above the Arctic Circle where the Sun remains visible at midnight during the summer months, meaning it is above the horizon for a full 24 hours.

Question 20

Above 66.5° N, the Sun

Accepted Answer

Above 66.5° N, which is known as the Arctic Circle, there is at least one day per year, during the summer solstice, when the Sun can be seen for a full 24 hours. This phenomenon is due to the tilt of the Earth's axis, allowing for continuous daylight during this period.

Quiz 1: Discovering the Night Sky

Twice per year, when day and night are equal in length, the Sun is at one of two positions in the sky known as equinoxes. These points are the intersections of which two planes in the sky?

If the horizon is considered to be split into northern and southern parts by the east-west line, can the Sun ever rise in the northern part of the sky when viewed from a mid-latitude site in the southern hemisphere?

For an observer standing at latitude 10° N, how many times during the year will the Sun pass precisely through a point directly overhead, the zenith?

When the Sun is at one of the equinoxes,

From Earth's North Pole, how long does the Sun remain above the horizon once it first appears at the beginning of spring?

The autumnal equinox is the time of the year when the

If the horizon is considered to be split into northern and southern parts by the east-west line, can the Sun ever rise in the southern part of the sky when viewed from a mid-latitude site in the northern hemisphere?

Where on Earth would an observer have to stand for the Sun to pass directly overhead (i.e., pass through zenith) at some time during the year?

The vernal equinox is the time of the year when the

What is the lowest latitude above which one would see the Sun for a full 24 hours on at least one day per year?

Which of these statements describing the situation at a mid-latitude site at the time of equinox is correct?

Imagine an observer standing on the South Pole (with the south celestial pole at their zenith) at the time of the vernal equinox. Where would the observer see the Sun all day?

On the day of the vernal equinox (approximately March 21 each year) , which of these conditions holds?

The Arctic Circle, above which the Sun can be seen for a full 24 hours on at least one day of the year, is a line around Earth at what latitude?

How often does the Sun cross the celestial equator in a given year?

Where would an observer have to be in either the northern or southern hemisphere for the Sun to remain below the horizon for a 24-hour period for at least part of a year?

The equinoxes are located at the intersections of the

The vernal equinox is one time of the year when the Sun

The "Land of the Midnight Sun" is so-named because

Above 66.5° N, the Sun