Section 3. Main ideas and supporting details.
1. Another use for Landsat is to find fresh water.
In dry areas such as deserts, Landsat photos may show black areas that indicate water or they may show red areas that indicate healthy plants.
People who are trying to find water in these dry areas can save time by looking in the places that are black or red on the LandSat pictures.
2. The fifth use is to warn us of natural disasters, such as the damage done by large forest fires, melting ice near the North and South Poles, and lines in the earth where earthquakes might happen.
3. Many experts believe that we must turn to the sun to solve the energy needs.
Solar energy is clean and unlimited.
It is estimated that the amount of solar energy falling on the continental United States is 700 times our total energy consumption.
It's possible to convert, or change this energy for our use. But the cost is the major problem.
The federal government is spending millions of dollars to find ways to convert, or change sunshine into economical energy.
By the year 2000, solar technology could be supplying about 25% of the United States' energy needs.
4. The major expense involved in a solar heating system is the purchase cost of all the parts of the system and the cost of their installation.
The approximate cost to buy and put a solar heating system into a three-bedroom house at present varies from 7,000 to 12,000 dollars.
This is a one-time cost that can be financed over many years.
This finance charge may be more expensive than heating with oil at present prices.