Satellites and Lunar Phenomena

Satellites are objects that orbit around larger celestial bodies and can be either natural or artificial. Understanding the differences between these types of satellites and their properties is essential for grasping their roles in space exploration and everyday life.

Natural vs. Artificial Satellites:

• Natural satellites form in space and are captured by a planet's gravitational field
• Artificial satellites are man-made and launched into orbit for specific purposes
• The Moon is Earth's only natural satellite, while examples of artificial satellites include the Hubble Space Telescope and the International Space Station

Properties of the Moon:

• Smaller mass than Earth
• Lower gravitational field strength
• Surface covered in craters caused by colliding rocks

Vocabulary: Eclipse - An astronomical event where one celestial object moves into the shadow of another.

Artificial Satellites:

• Polar satellites orbit over Earth's poles at altitudes of 200-1000 km
• They have quick orbital periods of 100 minutes to 1 hour 40 minutes
• Used for weather monitoring, military applications, and Earth photography
• Travel at speeds of 8000 m/s

Highlight: Artificial satellites serve various purposes such as telecommunications, weather forecasting, satellite navigation systems, and even espionage.

Phases of the Moon: The Moon's appearance changes throughout its orbit around Earth, resulting in different phases visible from our planet. These phases include:

1. New Moon
2. Waxing Crescent
3. First Quarter
4. Waxing Gibbous
5. Full Moon
6. Waning Gibbous
7. Last Quarter
8. Waning Crescent

Definition: Waxing refers to the increasing illumination of the Moon's visible surface, while waning refers to the decreasing illumination.

Understanding these concepts helps us appreciate the complexity of our solar system and the technological advancements that allow us to explore and utilize space for various purposes.

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.

Solar System Objects and Celestial Phenomena

The solar system comprises a vast array of objects, ranging from minuscule asteroids to enormous galaxies. Understanding the scale and relationships between these objects is crucial for comprehending our place in the universe.

• Celestial objects in order of size: asteroid, moon, planet, star, solar system, galaxy, Local Group, universe
• Planets distance from the Sun in order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
• Comets are balls of dust, gas, and ice with highly elliptical orbits around the Sun
• Earth's rotation and revolution, along with its axial tilt, cause day/night cycles and seasons

Vocabulary: NEOs $Near Earth Objects$ - Objects in space such as asteroids, comets, or meteoroids that sometimes pass near Earth.

Highlight: The universe is so vast that it affects how we perceive distant objects. Telescopes are necessary to observe distant planets, while neighboring galaxies appear as blurs in the sky.

Example: A light year, the distance light travels in one year, is used to describe vast cosmic distances. For instance, the Sun is 8 light minutes away from Earth, while Proxima Centauri, the next closest star, is four light years away.

Definition: Craters are formed when NEOs enter Earth's atmosphere and impact the surface, sometimes leaving behind massive holes.

The Earth's equator divides it into the Northern and Southern hemispheres, which experience seasons differently due to the planet's axial tilt as it orbits the Sun. This 23.5-degree tilt causes one hemisphere to receive more direct sunlight at different times of the year, resulting in the four seasons.

Highlight: Key dates for seasonal changes include:

• March 21/22: Spring equinox $North$, Autumn equinox $South$
• June 21/22: Summer solstice $North$, Winter solstice $South$
• September 22/23: Autumn equinox $North$, Spring equinox $South$
• December 21/22: Winter solstice $North$, Summer solstice $South$