National Aeronautics and Space Administration

Activity #6b
Evidence for Hidden Mass

Examine the "Evidence for Hidden Mass" graph. Note that the graph has a curve labeled "Solar System Planets" (in yellow) and a curve labeled "Galaxy F563-1" (in white). The curve for the Solar System shows the relationship between distance from the Sun and orbital velocity for each of the planets. The curve for the galaxy shows the relationship between distance from the galaxy center and velocity around that center for stars in the galaxy.

1. Finish writing the paragraph below by interpreting the data about Solar System planets on the "Evidence for Hidden Mass" graph.

   There are __________ solar system planets presented on the graph. The planets, from the closest to the Sun to the furthest from the Sun, are

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   Using the graph, the velocities of the solar system planets, from the lowest value to the highest value, are

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   Using the graph, the distances of the planets from the Sun are, from least to greatest,

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   In general, the further the planet is away from the Sun the __________ its velocity. The closer the planet is to the Sun the __________ its velocity.

2. Now use your own words to describe the graph for Galaxy F563-1. Describe the range of distances and velocities. Also describe the behavior of velocity as distance increases.

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