Astronomy: Meteoroids and Meteorites

Meteoroids and the Kuiper Belt

• Meteoroids can be as small as a piece of dust or as large as a car or building.
• Meteoroids have different names depending on their location, and if they enter Earth's atmosphere, they are called meteors, and if they hit the surface, they are called meteorites.
• The Kuiper belt is a region beyond the gas giants, containing dwarf planets, asteroids, meteoroids, ice, and dust.

Geocentric and Heliocentric Views of Our Solar System

• The Geocentric Theory states that the Earth is at the center of the universe, and all planets revolve around it.
• Aristotle and Ptolemy supported the geocentric theory, which prevailed for 1400 years.
• Heliocentrism, developed by Copernicus, states that the Sun is the center of our solar system, and the Earth and other planets revolve around it.
• Galileo supported Copernicus' theory, which clashed with religious views, leading to his house arrest.

Eclipses

• An eclipse is an astronomical event involving objects casting shadows on one another.
• There are two main types of eclipses: solar eclipses, which occur when the Moon casts a shadow on Earth, and lunar eclipses, which occur when the Earth casts a shadow on the Moon.
• Eclipses can only occur when the Sun, Earth, and Moon are aligned, which is called syzygy.
• Solar eclipses have three types: total, partial, and annular.

Phases of the Moon

• The Moon appears to change shape due to its position relative to the Earth and Sun.
• The Moon does not create its own light, it reflects the Sun's light.
• The phases of the Moon include New Moon, Full Moon, Waxing, and Waning.
• There are two ways to measure the Moon's orbit: Sidereal Month (27.3 days) and Synodic Month (29.5 days).

Seasonal Change

• Earth's axis causes day and night, and its orbit around the Sun causes seasonal changes.
• As Earth revolves around the Sun, different parts of the planet are tilted towards or away from the Sun, causing seasonal changes.
• The Northern and Southern Hemispheres experience opposite seasons due to their tilt towards or away from the Sun.
• Areas along the equator experience consistent 12 hours of daylight and 12 hours of night throughout the year.
• North and south of the equator, the length of day and night changes throughout the year, with longer days in summer and longer nights in winter.
• Equinoxes occur twice a year, with 12 hours of day and 12 hours of night everywhere on Earth.
• Solstices occur twice a year, with the most or least amount of sunlight, depending on the location.

Solar System

• Our solar system consists of 8 planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
• To be considered a planet, it must be in orbit around a star and dominate its orbit, meaning its mass must be greater than anything else that crosses its orbit.
• There are two main types of planets: terrestrial planets (smaller, hard, rocky surfaces) and gas giants (bigger, composed of gases and liquids).

Planet Classification

• Terrestrial planets: Mercury, Venus, Earth, and Mars
• Gas giants: Jupiter, Saturn, Uranus, and Neptune

Dwarf Planets and Moons

• Pluto is a dwarf planet, doesn't meet the definition of a planet because it doesn't dominate its own orbit.
• Moons are natural satellites that orbit planets or dwarf planets.
• Moons can be as large as planets; more massive planets tend to have more moons.

Asteroids and Meteoroids

• Asteroids are small, irregularly shaped objects made of rock and metal.
• Meteoroids are small pieces of metal or rock, can be as small as dust or as large as a car or building.

Kuiper Belt and Oort Cloud

• The Kuiper belt is a region beyond the gas giants, filled with dwarf planets, asteroids, meteoroids, ice, and dust.
• The Oort cloud marks the boundary of our solar system.

Geocentric vs. Heliocentric Views

• The geocentric theory: the Earth is at the center of the universe, and all planets revolve around it.
• Aristotle and Ptolemy supported the geocentric theory, which prevailed for 1400 years.
• The heliocentric theory: the Sun is at the center of our solar system, and planets revolve around it.
• Copernicus developed the heliocentric theory, which was supported by Galileo and has withstood the test of time.

Eclipses

• An eclipse is an astronomical event involving objects casting shadows on one another.
• There are two main types of eclipses: solar eclipses (Moon casts a shadow on Earth) and lunar eclipses (Earth casts a shadow on the Moon).
• Eclipses can only occur when the Sun, Earth, and Moon are aligned in a syzygy, which repeats in predictable patterns.

Solar Eclipses

• A solar eclipse can only occur during a New Moon, when the Moon is between the Earth and the Sun.
• There are three types of solar eclipses: total, partial, and annular.
• A total solar eclipse occurs when the Moon completely blocks the Sun, revealing the Sun's corona.

Lunar Eclipses

• Lunar eclipses occur when the Moon passes through Earth's shadow.
• Lunar eclipses can be partial or total, but not annular.
• During a total lunar eclipse, the Moon appears red, sometimes called a "blood moon".

Our Solar System

• Our solar system consists of 8 planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
• To be considered a planet, it must be in orbit around a star (like our Sun) and dominate its orbit (i.e., its mass must be greater than anything else that crosses its orbit).

Types of Planets

• Our solar system has two main types of planets: Terrestrial planets and Gas Giants.
• Terrestrial planets: Mercury, Venus, Earth, and Mars (smaller planets with hard, rocky surfaces).
• Gas Giants: Jupiter, Saturn, Uranus, and Neptune (larger planets composed of gases and liquids).

Smaller Objects in Our Solar System

• Dwarf planets: Pluto is a dwarf planet, which doesn't meet the new definition of a planet because it doesn't dominate its own orbit.
• Moons: natural satellites that orbit planets or dwarf planets (e.g., Jupiter has 79 confirmed moons).
• Asteroids: smaller than dwarf planets and moons, not large enough to form a spherical shape under gravity, made of rock and metal.
• Meteoroids: small pieces of metal or rock, can be as small as a piece of dust or as large as a car or building.
• Meteoroids have different names depending on their location: meteor (if it enters Earth's atmosphere) or meteorite (if it hits the surface).

The Kuiper Belt and Oort Cloud

• The Kuiper Belt is an area beyond the gas giants, filled with dwarf planets, asteroids, meteoroids, ice, and dust.
• The Oort Cloud marks the boundary of our solar system.

Geocentric vs. Heliocentric Views

• The Geocentric Theory: the Earth is at the center of the universe, and all planets revolve around it.
• Aristotle placed the Earth at the center of the universe, and all planets, sun, and stars around it.
• Ptolemy advanced the geocentric theory, adding mathematics to support it.
• Heliocentrism: the Earth and other planets revolve around the Sun, developed by Copernicus.
• Galileo supported the Copernican model, publishing his discoveries in two books, which led to controversy and house arrest.

Eclipses

• Solar eclipses: occur when the Moon passes between the Earth and Sun, blocking the Sun's light.
• Types of solar eclipses: total, partial, and annular.
• Lunar eclipses: occur when the Earth passes between the Moon and Sun, blocking the Sun's light from reaching the Moon.
• Types of lunar eclipses: partial, total, and there are no annular lunar eclipses.

Phases of the Moon

• The Moon appears to change shape as it orbits the Earth due to the position of the Moon relative to the Earth and Sun.
• The Moon does not create its own light, it reflects the Sun's light.
• The phases of the Moon: New Moon, Full Moon, waxing, and waning.

Seasonal Change

• Earth has an axis about which it spins, causing day and night.
• Earth orbits around the Sun in one year, causing different parts of the Earth to be tilted towards or away from the Sun.
• When the Northern Hemisphere is tilted away from the Sun, it experiences winter, and the Southern Hemisphere experiences summer.
• Areas along the equator get 12 hours of daylight and 12 hours of night consistently throughout the year.
• Equinox: a day with 12 hours of day and 12 hours of night everywhere on Earth, occurring twice a year (March and September).
• Solstice: two days each year that receive the most or least amount of sunlight (depending on where you live).