What percent of the universe is dark matter?

What is the mercury length of time for one revolution around the sun?

The model of human settlement suggests that uthe model of human settlement suggests that urban growth is patterned around transportation networks such as railroads and highways. a. burgess b. hoyt c. sauer d. von thunenrban growth is patterned around transportation networks

Ascientist makes a map using gis. one layer is an aerial photograph of farmland. other layers show water level changes and how crop cover has changed over time. what might the scientist be studying?