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Astronomy
Vocabulary
The Solar System
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Astronomy – The study of the moon, stars, and other objects in space.
Geocentric - Theory that all planets revolved around the Earth.
Heliocentric - Theory that all planets revolve around the sun.
Rotation - The spinning motion of a planet on its axis.
Revolution - The movement of an object around another object.
Ellipse - An oval shape, which may be elongated or nearly circular.
Astronomical Unit – the average distance between Earth and the sun, about 150,000,000 km.
Earth, Moon and Sun
1. Lunar - Refers to the moon
2. Solar - Refers to the sun
Space Exploration and NASA
1. Space shuttle – a spacecraft that can carry a crew into space, return to Earth, and then be reused
for the same purpose.
2. Space station – A large artificial satellite on which people can live and work for long periods.
3. Space probe – A space craft that carries scientific instruments that can collect data, but has no
human crew.
4. Rover – A small robotic space probe that can move about the surface of a planet or moon.
5. Satellite – An object that revolves around another object in space.
6. Geostationary Orbit – An orbit in which a satellite orbits Earth at the same rate as Earth rotates
and thus stays over the same place over Earth’s equator all the time.
7. Space Spin-off - An item that has uses on Earth but was originally developed for use in space.
Notes
The Solar System
1. Our solar system consists of the sun, the planets, their moons, and smaller objects.
2. In a geocentric model of the solar system, Earth is at the center of the revolving planets and stars.
Many early observers believed that the Earth was at the center of the universe.
3. In a heliocentric model of the solar system, the sun is at the center .
4. Copernicus worked out the arrangements of the known planets and how they orbit the sun in
1543. This idea was not accepted in ancient times because people could not accept that the earth
was not the center of the universe.
5. After years of detailed calculations, Kepler found that the orbit of each planet is an ellipse (late
1500’s).
6. One of the first to use a telescope, Galileo gathered evidence that convinced others the heliocentric
model was correct. (early 1600’s)
7. The four inner planets (Mercury, Venus, Earth, and Mars) are small and dense and have rocky
surfaces.
8. The four outer planets (Jupiter, Saturn, Uranus, and Neptune) are much larger than Earth and do
not have solid surfaces (they are often referred to as gas giants).
9. All the planets move in space in two major ways: rotation and revolution.
10. The imaginary line that passes through a planet's center and its poles is called the axis.
11. A planet rotates on its axis. One rotation of Earth takes about 24 hours and causes day and night.
12. In addition to rotating, planets revolve around the sun. One revolution of Earth around the sun is
called a year.
13. The path (orbit) of any planet around the sun is a slightly elongated circle, or ellipse.
Earth, Moon and Sun
1. Earth moves in space in two major ways: rotation and revolution.
2. The imaginary line that passes through Earth’s center and the North and South poles is Earth’s
axis.
3. The Earth rotates on its axis. One rotation takes about 24 hours and causes day and night.
4. In addition to rotating, Earth revolves around the sun. One revolution of Earth around the sun is
called a year.
5. Earth’s path (orbit) around the sun is a slightly elongated circle, or ellipse.
6. Like Earth, the moon moves in space in two major ways. It rotates on its own axis and revolves
around Earth. One revolution of the moon around Earth takes about 28 days.
Space Exploration and NASA
1. The American effort to land astronauts on the moon and return them to Earth was named the
Apollo program (1963-1972). The spacecrafts used during the Apollo program could only be used
once.
2. By 1981, NASA had developed the space shuttle which could be reused, meaning NASA no
longer had to build a new spacecraft for each mission.
3. NASA has used space shuttles to take satellites into orbit, repair damaged satellites and carry
astronauts and equipments to and from space stations.
4. A space station provides a place where long-term observations and experiments can be carried
out in space. The United States and 15 other countries constructed the International Space Station.
On board, astronauts from many countries are carrying out experiments in various fields of
science.
5. Space probes gather data about distant parts of the solar system and universe where humans
cannot easily travel. Some are equipped to photograph and analyze the atmosphere of a planet.
Others are equipped to land on a planet and analyze the material on its surface.
6. Some space probes release rovers that have instruments for collecting and analyzing soil and rock
samples.
7. Satellites are useful in monitoring atmosphere, observing other countries for military purposes,
GPS systems, communications systems, and collecting data on climate, land forms and other
terrestrial information. Some satellites are in a geostationary orbit.
8. The Stennis Space Center in Mississippi is America’s premier rocket engine test complex. At
Stennis, engines for all manned Apollo and space shuttle flights have been tested.
9. The space program has led to the development of many thousands of products, among them
consumer products, new material, medical devices and communication satellites (space spin-offs).