Satellites – JSS1 Basic Science Lesson Note (Third Term)

A satellite is a body that orbits, or moves around, a larger body in space such as a planet.

Behavioural objectives

By the end of the lesson, students should be able to:

1. define a satellite and give an example;
2. state the number of satellites of some planets in the solar system;
3. distinguish between natural and artificial satellites;
4. name some countries and their first satellites;
5. list the types of satellites and state their uses.

What is a satellite?

A satellite is a body that orbits a planet, for example, the Moon is a satellite of the Earth.

• Orbit: the curved path that a body follows around another body in space.
• Gravity: the pull of a planet that keeps its satellite moving in orbit around it.
• Moon: another name for a natural satellite of a planet.

How many satellites does each planet have?

The number of moons differs from planet to planet, and Mercury and Venus have none.

• Earth: has one natural satellite, the Moon.
• Mars: has two small moons, Phobos and Deimos.
• Giant planets: Jupiter, Saturn, Uranus and Neptune have many moons, and new ones are still being found.

• Pluto: is now classed as a dwarf planet, not a planet, and has five known moons.
• Older books: may give smaller numbers for the giant planets, because fewer moons were known then.

What are natural and artificial satellites?

There are two kinds of satellites: natural satellites and artificial satellites.

Natural satellites

Natural satellites are moons that orbit planets and were not made by people.

• Moon: the natural satellite of the Earth.
• Phobos and Deimos: the two natural satellites of Mars.
• Titan: a large natural satellite of Saturn.

Artificial satellites

Artificial satellites are man-made bodies launched by countries to orbit the Earth.

• Launch: a rocket carries the satellite into space.
• Orbit: the satellite then circles the Earth, held by gravity.
• Example: NigeriaSat-1 is a Nigerian artificial satellite.

What is the difference between natural and artificial satellites?

Which countries launched the first satellites?

The USSR launched the first artificial satellite, Sputnik 1, in 1957.

What are the types and uses of satellites?

There are eight main types of artificial satellites: astronomical, bio, observation, weather, communication, reconnaissance, space station and navigational.

1. Astronomical satellites: observe distant planets, galaxies and other outer space objects. The Hubble Space Telescope is an example.
2. Bio satellites: carry living organisms, especially for scientific experiments.
3. Observation satellites: are used for geographical studies, photographing areas and map making.
4. Weather satellites: monitor weather conditions in the atmosphere and send the information to ground stations.
5. Communication satellites: send information quickly from one place to another, such as phone calls and television signals.
6. Reconnaissance satellites: are used for military or intelligence purposes, such as observing enemy locations or troop movements.
7. Space station satellites: are built for people to live on in outer space for weeks, months or years. The International Space Station is an example.
8. Navigational satellites: send radio time signals that let receivers on the ground find their exact location.

Evaluation

1. What is a satellite?
2. Give one example of a natural satellite.
3. What is the difference between a natural satellite and an artificial satellite?
4. Which satellites are used to monitor weather conditions?
5. Name the first satellite launched by Nigeria and the year it was launched.

Assignment

1. List any four types of satellites and state one use of each.
2. Name the first satellite of any three countries in the table above, with the year each was launched.