Satellites, what are they?
What Is a Satellite?
04.13.10
NASA has more than a dozen Earth science satellites in orbit. They help NASA
study the oceans, land and atmosphere. Image Credit: NASA
A satellite is a
moon, planet or machine that orbits a planet or star. For example, Earth is a
satellite because it orbits the sun. Likewise, the moon is a satellite because
it orbits Earth. Usually, the word "satellite" refers to a machine that is
launched into space and moves around Earth or another body in space.
Earth and the moon are examples of natural satellites. Thousands of
artificial, or man-made, satellites orbit Earth. Some take pictures of the
planet that help meteorologists predict weather and track hurricanes. Some take
pictures of other planets, the sun, black holes, dark matter or faraway
galaxies. These pictures help scientists better understand the solar system and
universe.
Still other satellites are used mainly for communications,
such as beaming TV signals and phone calls around the world. A group of more
than 20 satellites make up the Global Positioning System, or GPS. If you have a
GPS receiver, these satellites can help figure out your exact location.
04.13.10
NASA has more than a dozen Earth science satellites in orbit. They help NASA
study the oceans, land and atmosphere. Image Credit: NASA
A satellite is a
moon, planet or machine that orbits a planet or star. For example, Earth is a
satellite because it orbits the sun. Likewise, the moon is a satellite because
it orbits Earth. Usually, the word "satellite" refers to a machine that is
launched into space and moves around Earth or another body in space.
Earth and the moon are examples of natural satellites. Thousands of
artificial, or man-made, satellites orbit Earth. Some take pictures of the
planet that help meteorologists predict weather and track hurricanes. Some take
pictures of other planets, the sun, black holes, dark matter or faraway
galaxies. These pictures help scientists better understand the solar system and
universe.
Still other satellites are used mainly for communications,
such as beaming TV signals and phone calls around the world. A group of more
than 20 satellites make up the Global Positioning System, or GPS. If you have a
GPS receiver, these satellites can help figure out your exact location.
Satellites!
Why Are Satellites Important?
The bird's-eye view that
satellites have allows them to see large areas of Earth at one time. This
ability means satellites can collect more data, more quickly, than instruments
on the ground.
Satellites also can see into space better than telescopes
at Earth's surface. That's because satellites fly above the clouds, dust and
molecules in the atmosphere that can block the view from ground level.
Before satellites, TV signals didn't go very far. TV signals only
travel in straight lines. So they would quickly trail off into space instead of
following Earth's curve. Sometimes mountains or tall buildings would block
them. Phone calls to faraway places were also a problem. Setting up telephone
wires over long distances or underwater is difficult and costs a lot.
With satellites, TV signals and phone calls are sent upward to a
satellite. Then, almost instantly, the satellite can send them back down to
different locations on Earth.
The bird's-eye view that
satellites have allows them to see large areas of Earth at one time. This
ability means satellites can collect more data, more quickly, than instruments
on the ground.
Satellites also can see into space better than telescopes
at Earth's surface. That's because satellites fly above the clouds, dust and
molecules in the atmosphere that can block the view from ground level.
Before satellites, TV signals didn't go very far. TV signals only
travel in straight lines. So they would quickly trail off into space instead of
following Earth's curve. Sometimes mountains or tall buildings would block
them. Phone calls to faraway places were also a problem. Setting up telephone
wires over long distances or underwater is difficult and costs a lot.
With satellites, TV signals and phone calls are sent upward to a
satellite. Then, almost instantly, the satellite can send them back down to
different locations on Earth.