OwlSheets Students

Behind the Ridge: A Valley Town's Winter Without Sun

0 / 10

Behind the Ridge: A Valley Town's Winter Without Sun

Use Sun data and a lamp-and-globe model to explain shade, seasons and the Moon.

Part 1: Twelve weeks of shade

Read the passage and Table 1, then answer questions 1–5.

The Sun Return Festival

1Greyhaven Hollow is a small mountain town at 47° north latitude. It sits at the bottom of a deep valley that runs from east to west. Just south of town, a steep forested ridge rises high above the rooftops. Seen from the town square, the top of the ridge is 26° above the horizon due south. Each winter, for about twelve weeks, the noon Sun stays behind the ridge and no direct sunlight reaches the square, although the sky above is still bright. In summer, by contrast, sunlight floods the square from late morning until late afternoon. The town marks the first day the Sun peeks over the ridge again with a Sun Return festival.

2Eighth grader Zsófia Szántó-Obi and her science class wrote a page for the festival's website. They used a sky app to record the height of the noon Sun and the length of the day on flat ground at 47° N (Table 1). They also looked up Earth's distance from the Sun: about 147 million km in early January and about 152 million km in early July.

3To explain the data, the class built a model. A lamp in the middle of a dark room stood for the Sun. A globe with its axis tilted 23.5° was carried in a big circle around the lamp, and its axis always pointed toward the same corner of the room. A sticker marked Greyhaven Hollow. At one spot on the circle, the north end of the axis leaned toward the lamp, and the light struck the sticker from high above. Half a circle later, the north end leaned away from the lamp, and the light struck the sticker at a low slant.

4Next, the class added a small white ball for the Moon and carried it around the globe once for each trip of a month. Like the globe, the ball was always half lit by the lamp. Their teacher, Mr. Osvaldo Okoro-Haldane, added one more fact: the Moon's orbit is tipped only about 5° from the path of Earth around the Sun, so the Moon moves across the sky along nearly the same paths that the Sun takes at different times of year.

Table 1: Sun Data for 47° N (flat ground)
Date	Noon Sun height	Day length (h)
September 22	43°	12.1
October 21	32°	10.4
November 21	23°	9
December 21	19.5°	8.4
January 21	23°	9.1
February 21	32.5°	10.6
March 20	43°	12.1
June 21	66.5°	16

1.

Use Table 1 and paragraph 1. Circle each date when the noon Sun is higher than the ridge top, so direct sunlight reaches the square at noon.

2.

Use Table 1 and paragraph 1.

On December 21, the noon Sun is ° below the top of the ridge. On flat ground, the June 21 day is about times as long as the December 21 day (round to the nearest tenth).

3.

Use the model in paragraph 3. Which globe position matches the town on December 21, and why?

A. North end leaning toward the lamp, because the ridge then blocks the lightB. Axis standing straight up, because the tilt goes away for part of each winterC. North end leaning away from the lamp, because light then reaches the town at a low slantD. North end leaning toward the lamp, because the town is then closest to the Sun

4.

A festival visitor says, "The square is shady in winter because Earth is farther from the Sun then." Which evidence from the page best shows a problem with this idea?

A. The noon Sun is 43° high on both September 22 and March 20.B. The ridge top is 26° above the horizon as seen from the square.C. Earth is about 147 million km from the Sun in January and 152 million km in July.D. The June 21 day lasts 16 h on flat ground at 47° N.

5.

Imagine a town at 47° south latitude in a valley with a 26° ridge due north of its square. Based on the model, when would that square most likely miss the noon Sun?

A. From about February to April, while Earth moves closer to the SunB. From about May to July, when the south end of the axis leans awayC. From about November to January, the same weeks as Greyhaven HollowD. From about August to October, when Earth is farthest from the Sun

Part 2: The Moon over the ridge

Use the model in paragraphs 3 and 4 and Table 1 to answer questions 6–10.

6.

Will the full moon in late December clear the ridge when it is highest, around midnight?

A. Yes. It is opposite the Sun, so it rides high, near the June noon Sun's path.B. Yes. The Moon is closer to Earth in winter, so it looks higher in the sky.C. No. At midnight a full moon sits inside Earth's shadow, so it is hidden.D. No. Like the December noon Sun, it stays about 20° high, below the ridge.

7.

Zsófia finds that the full moon in late June never clears the ridge, even at midnight. Which explanation fits the model best?

A. In June the Moon's orbit tips 23.5° away from Earth, so it stays near the horizon.B. June nights are short, so the full moon sets before it has time to climb high.C. The June full moon is farther from Earth, so it sinks lower in the sky than in winter.D. The June full moon is opposite the Sun, so it follows a low path like the December Sun's.

8.

Use the model. Fill in each blank with a phase from the word bank. Two words are left over.

A solar eclipse can happen only at , when the Moon is between the Sun and Earth. A lunar eclipse can happen only at , when Earth is between the Sun and the Moon.

9.

A partial solar eclipse is forecast for noon on January 21. Use Table 1. What will people standing in the town square most likely see?

A. No Sun at all; they must climb the ridge or leave the valleyB. A reddish Moon, since Earth's shadow falls on the townC. A full moon covering part of the Sun high in the southern skyD. The Sun with a bite out of it, low over the top of the ridge

10.

The festival website needs a short answer to the question "Why does our square lose the Sun every winter?" Write a claim, use at least two numbers from Table 1 or paragraph 2 as evidence, and use the lamp-and-globe model to explain your reasoning.