Answer: is constant
Explanation:
In order to analyze the velocity of the stars within a galaxy, the <u>galaxy rotation curves</u> (developed by the American astronomer Vera Rubin) are used. These graphs are elaborated as a scatter diagram in which the orbital velocity of the stars present in a galaxy is represented on the Y axis and the distance of these stars to the center of the galaxy on the X axis.
Thanks to this diagram, it has been possible to observe a characteristic behavior in the rotation speed of the stars (and gas) present in the galaxies, which differs from the rules of the orbital movement of the planetary systems postulated by Newton and Kepler.
This means that in these galaxy rotation curves it has been observed that the rotation speed of stars and gas is "constant", regardless of the distance to the center of the galaxy. This discrepancy and these results were then used to demonstrate the existence of dark matter in the universe.
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<u>Answer:</u>
Pacific Ocean formed by the same processes that cause the current geologic activity and Beautiful mountains are the reasons why many people live on the Ring of Fire.
<u>Explanation:</u>
The volcanic islands around the Pacific ocean have formed on the tectonic plates due to various geologic processes. These islands have highly fertile soil and geothermic energy from the underground steam caused due to the volcanic magma can also be harnessed to obtain an economic advantage. There's also an incredible scenery with various volcanic mountains and hot geysers that attract hundreds of tourists from all over the world. This provides various job opportunities in the field of tourism.
