Science Solar System - 6th HMH unit 2

Dwarf planets are smaller than planets. What is another way that dwarf planets are different?

• They are not spherical

• They do not orbit the sun

• They have large objects in their orbit

• They move more slowly along their orbits

Answer explanation

Requirements to be a PLANET: The object must be in orbit around the Sun. The object must be massive enough to be rounded by its own gravity. It must have cleared the neighborhood around its orbit. POOR PLUTO, does't fit the bill.

As an astronomer observes an object in space that has an irregular shape, that orbits the sun in a highly elliptical orbit, and that is made of ice and rock. Which object is the astronomer most likely observing?

• moon

• comet

• asteroid

• meterioid

Answer explanation

A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing.

An astronomer uses parallax to determine a star’s distance from Earth. Which statement correctly describes parallax?

• Stars closer to Earth will have a dimmer appearance.

• Stars farther away from Earth will have a dimmer appearance.

• Stars closer to Earth will appear to have a greater shift in position.

• Stars farther away from Earth will appear to have a greater shift in position.

Answer explanation

Parallax can be used to measure the distance to an object based on the size of the apparent shift in position when the object is viewed from two places. The bigger the apparent shift in position is, the closer the object is to the viewer.

The picture shows a model of the solar system.

Which statement describes a limitation of the model?

• It cannot show how the planets orbit the sun.

• t cannot show the relative sizes of each planet.

• It does not show the order of the planets, from closest to the sun to farthest from the sun.

• It does not show the gravitational force exerted by each planet.

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Early astronomers noticed that some stars in the sky appeared to move together across the sky as constellations. How do astronomers today explain this motion?

• The sun’s gravity keeps the stars together because they orbit the sun at the same rate.

• The stars appear to move together along a path because of Earth’s rotation on its axis.

• Gravitational attraction between the stars keeps them fixed relative to each other as they move.

• The stars move around Earth in the same way, so their positions relative to each other stay the same.

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The table shows events that led to the current theory that the sun is the center of the solar system.

• 1, 2, 3

• 1, 3, 2

• 2, 1, 3

• 3, 1,2

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The dotted lines in the picture show orbital paths of objects.

Which object orbits E?

• Object D

• Object B

• Object A

• Object C

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Is this model to scale regarding the sizes of the planets and distances between them? Why or why not?

• Yes. That's why the outer planets are showin in a separate table

• No. The outer planet distances are drawn to scale, but the inner planets need to be drawn farther from the sun to be visible.

• No. The distances in the solar system are too great to produce a model accurate to distance that still has inner planets visible.

Answer explanation

The sizes of the planets and their distances from the sun make it nearly impossible to show both scale in a model that fits on a single page.

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Based on the model, why are Ceres and Pluto classified as dwarf planets rather than planets?

• Dwarf planets have irregularly shaped orbits and planets have elliptical orbits

• Ceres and Pluto are both round

• Neither Ceres nor Pluto has cleared its orbital path of other objects

Answer explanation

The plents in the model have cleared their orbit paths, but Ceres and Pluto have not so they cannot be true planets. Ceres is in the asterioid belt, Pluto is in the Kuiper Belt, but true planets do not exist in orbital paths containing other large space ojects. Both planets and dwarf planets are round, and both types of ojects have elliptical orbits.

How can the observed phases of Venus provide evidence to support a specific model of the Solar System? Check three (3) that apply.

• The model that better predicts the phases is likely to be more correct.

• The phases of Venus follow a predictable pattern that results from the relative positions of the Sun, Venus, and Earth.

• The models predict the phases of Venus differently beause the relative positionsof the three bodies are different in each model.

• Neither model accurately predicts the observed phases of Venus, so neither model is accurate.

Answer explanation

The difference between the models is the relative positions of the sun, Earth, and Venus.

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NGSS.MS-ESS1-1