Worksheet

Sunspots on the Screen: Sizing Up the Sun

Grade 8 solar system scale practice: measure sunspots on a projected Sun image, then use diameter and mass data to compare the Sun, Jupiter, Earth and the Moon.

Grade 8ScienceInteractive · Printable

Aligned toMS-ESS1-3

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Single worksheet
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1 NGSS standard
Printable answer key
11 questions
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Details

Format: Interactive · Printable
Grade: Grade 8
Subject: Science
Question types: Fill in the blank, Multiple choice, Sorting, Short answer

About this worksheet

What students practice

Students use an image scale to find the real sizes of sunspots and compare them with Earth.
Students analyze diameter and mass data to describe how the Sun and Jupiter compare with the rest of the solar system.

How to use

Go over the screen scale in paragraph 2 together before students start; calculators help for Part 2. Remind students never to look at the Sun directly or through any lens.

Curriculum

NGSS standard covered

MS-ESS1-3

Analyze data to find the scale properties of objects in the solar system.

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Name Date

Sunspots on the Screen: Sizing Up the Sun

Measure sunspots on a projected image and compare the Sun with the planets.

Part 1: Measuring sunspots

Read the passage and Table 1, then answer questions 1–4.

The Observatory Above Town

1Above a small mountain town, a solar observatory sits on a rocky ridge where the air is thin and dry. The town below sits in a steep valley where road crews watch for rockslides after storms, but up on the ridge the sky is often clear, and there is less air above the telescope to blur the view. On summer Saturdays it opens to visitors, and eighth grader Oskar Ferreira-Lund helps as a volunteer. The observatory's telescope never sends sunlight into anyone's eye. Instead, it projects an image of the Sun onto a white screen in a dark room, which is the only safe way the guides let visitors look at the Sun. Looking at the Sun directly, or through binoculars or a telescope, can badly damage the eyes.

2The guide, Ms. Marguerite Tshabalala, adjusts the telescope so that the Sun's image on the screen is exactly 139.2 mm wide. Because Earth keeps turning, the image would slowly drift off the screen, so a motor turns the telescope to follow the Sun. The real Sun is about 1,392,000 km wide, so every 1 mm on the screen stands for 10,000 km on the Sun. One morning Oskar traced the dark sunspots on paper taped to the screen and measured how wide each one was (Table 1). Sunspots are cooler, darker patches on the Sun's surface. Most last from a few days to a few weeks.

3Visitors often ask how the sunspots compare with Earth, so Ms. Tshabalala keeps a second table by the screen (Table 2). It lists the diameters and masses of a few objects, with each mass compared with Earth's mass. She also reminds visitors that the Moon orbits about 384,000 km from Earth.

4Oskar wants to build a lobby display at the same scale as the screen image. He plans to show Earth as a tiny dot and to measure, out the door and down the hall, how far from the Sun image the dot would have to sit. Earth is about 150 million km from the Sun. He also wants a sign that compares the Sun with the planets by mass, using the numbers in Table 2.

Table 1: Oskar's Sunspot Tracing (1 mm = 10,000 km)
Sunspot	Width on the screen (mm)
A	0.8
B (large group)	12.5
C	3.2
D	2
E	0.6

Table 2: Sizes and Masses (Earth's mass = 1)
Object	Diameter (km)	Mass (Earth = 1)
Sun	1,392,000	333,000
Jupiter	139,800	318
Saturn	116,500	95
Earth	12,742	1
Moon	3,474	0.012
All 8 planets together	—	447

Use Table 1 and the scale in paragraph 2. Use Table 2 for Earth's diameter, and round to the nearest whole number.

Sunspot group B is about km wide. About Earths lined up side by side would stretch across it.

Use Tables 1 and 2. Sort each sunspot by its real width compared with Earth's diameter.

Sunspot ASunspot BSunspot CSunspot DSunspot E

Wider than Earth	Narrower than Earth

Use Tables 1 and 2. Which comparison of sunspot group B is correct?

A. It is a little narrower than Saturn and about 4 times as wide as the Moon.
B. It is a little narrower than Jupiter and about 10 times as wide as Earth.
C. It is a little wider than Jupiter and about 10 times as wide as Earth.
D. It is about as wide as Earth and a little narrower than the Moon's orbit.

Use Table 2. Round to the nearest whole number.

The Sun's diameter is about times Earth's diameter.

Part 2: The Sun, the planets and the lobby display

Use Table 2 and paragraphs 3 and 4 to answer questions 5–10.

A visitor asks whether the Moon's whole orbit around Earth could fit inside the Sun. Use Table 2 and paragraph 3. Which answer is correct?

A. No. The Moon's orbit and the Sun are almost exactly the same width.
B. Yes, but just barely, with less than 1,000 km to spare.
C. Yes. The Sun is about 1.8 times as wide as the Moon's orbit.
D. No. The Moon's orbit is about 4 times as wide as the Sun.

Use Table 2. Round each percent to the nearest whole number.

Jupiter has about % of the mass of all 8 planets together. Saturn has about % of it.

Use Table 2. Add the Sun's mass and the mass of all 8 planets. Round to the nearest tenth of a percent.

The Sun holds about % of that total mass.

Which conclusion do your answers to questions 6 and 7 support best?

A. The mass is shared about evenly among the Sun and the eight planets.
B. Jupiter has more mass than the Sun, since it is the largest planet.
C. The planets together have about as much mass as the Sun, mostly in Earth.
D. The Sun has nearly all the mass, and Jupiter has most of what is left.

Use the scale 1 mm = 10,000 km and paragraph 4 for Oskar's lobby display. There are 1,000 mm in 1 m. Round the dot's width to the nearest tenth.

The Earth dot should be about mm wide, and it should sit about m from the 139.2 mm Sun image.

10.

Use your answers to question 9. What does Oskar's display show about the solar system?

A. Earth is tiny next to the Sun, and the space between them is huge compared with both.
B. Earth is about one tenth as wide as the Sun, and it sits just outside the Sun's edge.
C. Earth is tiny next to the Sun, and the two sit closer together than they are wide.
D. The Sun and Earth are about the same size, but they sit about 15 m apart.

11.

A visitor says, "Sunspots are just tiny specks, much smaller than Earth. Earth is a big object compared with anything on the Sun." Make a claim about this idea. Use at least three numbers from Table 1, Table 2 or your answers as evidence, and explain your reasoning about scale.