Science STAAR Category

The Milky Way galaxy is described as a disk of stars orbiting a central point on the disk. Which of these best explains why people on Earth cannot see the entire shape of the Milky Way? 

• Earth is a part of this galaxy.
• Many more stars exist outside the galaxy.
• The stars in the center of the galaxy are extremely small. 
• The center of the galaxy consists of a dense cluster of stars.

The diagram below shows four phases of the moon as it revolves around Earth. A student builds a model based on this diagram. The student uses foam balls to represent the moon and Earth and a flashlight to represent the sun. The student should shine the flashlight on the model of Earth from Position ____.

• 1
• 2
• 3
• 4

An object will continue moving in a straight line unless it is acted on by an unbalanced force. Which of the following best explains Earth's motion?

• There is no unbalanced force acting on Earth because space is empty and nothing touches Earth.
• The gravitational force pulling Earth towards the sun is equal and opposite to the force pulling the sun towards Earth, so there is no unbalanced force acting on Earth.
• The sun moves in an elliptical orbit around Earth, and the sun's gravity pulls Earth along.
• Earth moves in an elliptical orbit around the sun because the gravitational force of the sun attracts Earth.

A student keeps a record of the phases of the moon for one month. On the first night of the student's observations, the full moon is visible in the sky. After the full moon, which of these phases will the student observe next?

• Waxing crescent moon
• Waxing gibbous moon
• Waning crescent moon
• Waning gibbous moon

The Hertzsprung-Russell diagram below shows how the brightness, surface temperature, and color of stars are related. Which of these observations of Bernard's Star is most likely accurate?

• Barnard's Star is less bright than the sun, has a surface temperature below 3,800 K, and is red.
• Barnard's Star is less bright than the sun, has a surface temperature above 3,000 k, and is red.
• Barnard's Star is brighter than the sun, has a surface temperature below 5,300 K, and is yellow
• Barnard's Star is brighter than the sun, has a surface temperature above 5,300 K, and is yellow.

Why does Earth get more energy from the sun than from all other stars in the universe combined?

• The sun is much larger than the other stars.
• The sun is much hotter than the other stars.
• The sun is much more dense than the other stars.
• The sun is much closer than the other stars.

The diagram below models Mercury and Venus orbiting the sun. What force causes Venus to travel along a curved path instead of moving in a straight line as indicated by the dashed line in the diagram?

• Electromagnetic attraction between the sun and Venus
• Gravitational attraction between the sun and Venus
• Electromagnetic attraction between Mercury and Venus
• Gravitational attraction between Mercury and Venus

A Hertzsprung-Russell diagram is shown below. Based on this diagram, which type of stars would belong to spectral class M and have the highest luminosity?

• Main-sequence stars
• Giants
• White dwarfs
• Supergiants

Some students used records from the U.S. Naval Observatory to make the table below of the percent of the moon that was visible on each night in January 2011. Based on these data, what part of the lunar cycle occurred between January 5 and January 7?

• Waxing crescent moon
• Waning crescent moon
• Full moon
• New moon

The moon reflects different amounts of sunlight onto Earth at different times. This reflected sunlight is commonly called moonlight. The graph below shows the intensity of moonlight at different times in a lunar cycle. Which moon phase most likely occurs at the time in the cycle represented by an X on the graph?

• A
• B
• C
• D