Science Category

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

Four students are asked to describe a nebula and a star. Their responses are shown in the table below. Which student described these two celestial bodies correctly?

• Student 1
• Student 2
• Student 3
• Student 4

The table below shows the distances of three stars from the sun. Students were asked to make a model of the three stars and to include the sun and Earth in the model. They chose to use a scale of 1 meter: 1 light-year.

• A
• B
• C
• D

A phase of the moon is shown below. 

• A
• B
• C
• D