National Science Education
Earth in the Solar System
Understandings about Science
The earth is the third planet from the sun
in a system that includes the moon, the sun, eight other planets and their
moons, and smaller objects, such as asteroids and comets. The sun,
and average star, is the central and largest body in the solar system.
Most objects in the solar system are in regular
and predictable motion. Those motions explain such phenomena as the
day, the year, the phases of the moon, and eclipses.
Gravity is the force that keeps planets in
orbit around the sun and governs the rest of the motion on the solar system.
Gravity alone holds us to the Earth's surface and explains the phenomena
of the tides.
The sun is the major source of energy for
phenomena on the Earth's surface, such as growth of plants, winds, ocean
currents, and the water cycle. Seasons result from variations in
the amount of the Sun's energy hitting the surface, due to the tilt of
the Earth's rotation on its axis and the length of the day.
Scientific inquiry and technological design
have similarities and differences. Scientists propose explanations
for questions about the natural world, and engineers propose solutions
relating to human problems, needs, and aspirations. Technological
solutions are temporary; technologies exist within nature and so they cannot
contavene physical or biological principles; technological solutions have
side effects; and technologies cost, carry risks, and provide benefits.
Many different people in different cultures
have made and continue to make contributions to science and technology.
Science and technology are reciprocal.
Science helps drive technology, as it addresses questions that demand more
sophisticated instruments and provides principles for better instrumentation
and technique. Technology is essential to science, because it provides
instruments and techniques that enable observations of objects and phenomena
that are otherwise unobservable due to factors such as quantity, distance,
location, size, and speed. Technology also provides tools for investigations,
inquiry, and analysis.
Perfectly designed solutions do not exist.
All technological solutions have tradeoffs, such as safety, cost, efficiency,
and appearance. Engineers often build in back-up systems to provide
safety. Risk is part of living in a highly technological world.
Reducing risk often results in new technology.
Technological designs have constraints.
Some constraints are unavoidable; for example, properties of materials,
or effects of weather and friction; other constraints limit choices in
the desigh, for example, environmental protection, human safety, and aesthetics.
Technological solutions have intended benefits
and unintended consequences. Some consequences can be predicted,