Astronomy Observations Before Telescopes

Observations before the Telescope

• Herds migrate with the seasons, and plants produce berries and seeds at specific times of the year.
• The moon's shape appears to remain constant over 28 days.
• The sun rises in one direction and sets in the other.
• Stars rise approximately 4 minutes earlier each night.
• The moon has phases and rises and sets at different times than the sun and stars.
• Observations revealed a variety of celestial bodies, with stars staying in the same positions relative to each other, forming patterns called constellations.

Celestial Bodies and Ancient Views

• Celestial bodies refer to objects in space.
• A constellation is a group of stars.
• Wanderers (planets) are celestial bodies that rise and set at different times.
• Planets do not produce their own energy and travel in orbit around a star.
• Indigenous views were governed by interconnection to nature, ancestor spirits, and the creators, with knowledge shared through natural phenomena, including stars.

Geocentric and Heliocentric Models

• Geocentric model: an earth-centered universe (incorrect).
• Aristotelian view: Earth at the center, with planets and stars attached to transparent spheres orbiting the Earth.
• Ptolemaic view: planets orbit on epicycles to explain retrograde motion and changing brightness.
• Heliocentric model: a sun-centered universe (correct).
• Key figures: Copernicus, Galileo, Kepler, Newton, and Einstein.

Our Solar System

• The solar system includes eight planets that orbit the sun.
• Inner (Terrestrial) planets: Mercury, Venus, Earth, and Mars.
• Outer (Jovian) planets: Jupiter, Saturn, Uranus, and Neptune.
• The sun is 100 times larger than the Earth, comprising 99.8% of the solar system's mass.

Planets

• Mercury: closest planet, one day is 176 Earth days, one year is 88 days, small atmosphere, large temperature range, rocky.
• Venus: hottest planet, one day is 243 Earth days, one year is 225 Earth days, large atmosphere, rocky.
• Earth: one moon, rocky.
• Mars: days are just longer than one Earth day, one year is 687 Earth days, average temperature is -60°C, rocky.
• Jupiter: gas giant, 75 moons, Jovian, gaseous.
• Saturn: gas giant, large ring, Jovian, one day is just under 11 hours long, one year is 29 Earth years.
• Uranus: four times the diameter of the Earth, 17 hours in one day, 84 Earth years, gaseous, Jovian.
• Neptune: one day is 16 hours long, one year is 165 Earth years, gaseous, Jovian.

Beyond Our Solar System

• Nebula: an interstellar cloud of gas and dust created by the formation and destruction of stars.
• Galaxy: a system of stars, dust, celestial bodies, and stars held together by gravity.
• Stars: burning balls of gas created by nuclear fusion when a dense cloud of gas and matter collide.