Santa Fe College

The framework for understanding the universe's operations was established by Kepler and Newton.
Their combined work covers planetary motion and laws governing the entire universe.
Kepler: Known for his three laws of planetary motion and discovering how planets orbit the sun.
Newton: Developed four laws of motion, leading to a total of seven laws (3 Kepler + 4 Newton) describing universal motion.

Newton's laws apply to all forms of motion, not just celestial bodies; they encompass everything from planets to everyday actions.

Definition: An object at rest remains at rest, and an object in motion continues in motion unless acted upon by an external force.
Example: A tennis ball on a table remains stationary until pushed.
- Factors like friction act as external forces that stop the motion.

Definition: The acceleration of an object is directly proportional to the force acting on it and inversely proportional to the mass of the object.
Formula: Acceleration (a) = Force (F) / Mass (m)
- This relationship means that heavier objects require more force to accelerate.
Key Insight: Direction of acceleration is the same as the direction of the applied force.

Definition: For every action, there is an equal and opposite reaction.
Example: When object 1 exerts a force on object 2, object 2 exerts the same force back on object 1.
Illustration: Weight acts down on a chair, equal force acts upward from the chair to balance it out.

Newton's Law of Gravity states that every two objects exert a gravitational force on each other, defined by the formula:
- F = G * (M1 * M2) / r^2
  - F: gravitational force
  - G: gravitational constant (same throughout the universe)
  - M1 and M2: masses of the two objects
  - r: distance between center of mass of both objects.
Key Point: Always measure distance from center of mass; failing to do so leads to incorrect calculations (e.g., zero distance implying infinite force).

The Earth's Tilt: Seasons are primarily caused not by the distance from the Sun but by the tilt of the Earth's axis.
Summer vs. Winter: In summer, the northern hemisphere tilts towards the sun, leading to direct sunlight and warmth. In winter, it tilts away, receiving sunlight at an angle, resulting in cool temperatures.
Heating Effect:
- Direct sunlight heats a smaller area more efficiently than the same amount of sunlight spread over a larger area.
- Example: When sunlight hits the ground directly (summer), it heats a smaller area compared to sunlight hitting at an angle (winter).

Future discussions will focus on:
- The phases of the moon: how and why they change.
- Eclipses: the conditions required for solar and lunar eclipses, involving the Earth, Moon, and Sun.
- It takes 4 weeks for the moon to go around earth one time.
- change in geometry is the reason we don’t always see half the moon.
- phases of the moon = changing the amount of the moon we see.
syncronus rotation: occurs when rotation speed and revolution speed are exactly the same.
the suns gravity acts as friction.
eclipse = sun, earth & moon
eclipse is when objects moves into the shadow of another object. Solar eclipse & lunar eclipse.
eclipse is when an object moves into the shadow of another object. Solar eclipse & lunar eclipse.
solar = total, partial, & annular
lunar = total, partial, & pen-umbular.
umbral = total solar eclipse
pen-umbral shadow = partial
total lunar eclipse = blood moon
total = completely inside umbral shadow
pen-umbral = inside pen-umbral only.
partial = moon is in both umbral and pen-umbral.
equinox forms when the equator and ecliptic connect.

Wavelength