Satellites and Lunar Phases
This page explores the concept of satellites, both natural and artificial, and explains the phases of the Moon as seen from Earth.
Satellites are defined as objects that orbit around a celestial body. They can be either natural, like the Moon, or artificial, like the Hubble Space Telescope or the International Space Station.
Vocabulary: A satellite is an object that orbits around a larger celestial body, either naturally occurring or man-made.
The page compares natural and artificial satellites:
- Natural satellites form in space and are captured by a planet's gravitational field.
- Artificial satellites are launched into space by humans for specific purposes.
- Natural satellites serve no direct purpose for humans, while artificial ones assist with tasks like telecommunications, weather forecasting, and navigation.
The Moon's properties are described, including its smaller mass compared to Earth and its lower gravitational field strength. The presence of craters on the Moon's surface is explained as the result of collisions with rocks.
Highlight: The Moon is Earth's only natural satellite and has a lower gravitational field strength than our planet.
The phases of the Moon are illustrated, showing how the Moon's appearance changes throughout its orbit around Earth. The phases include new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, and waning crescent.
Definition: An eclipse is an astronomical event where one celestial object moves into the shadow of another.
The page concludes with information about artificial satellites, specifically polar satellites. These orbit over Earth's poles, have quick orbital periods of 100 minutes to 1 hour 40 minutes, and travel close to Earth at altitudes between 200km and 1000km. They are used for monitoring weather, military applications, and taking photographs of Earth.
Example: Polar satellites travel at speeds of about 8000 meters per second and complete an orbit around Earth in less than two hours.
