Solar System Dynamics and Celestial Mechanics

Science Study Sheet: The Solar System

Inner Planets: Mercury, Venus, Earth, and Mars.

Outer Planets (Gas Giants): Jupiter, Saturn, Uranus, and Neptune.

Dwarf Planets

Pluto, Ceres, Haumea, Makemake, and Eris.

Characteristics of Stars

• Red Stars: These are the coolest stars with the lowest temperatures (e.g., 3,000°C). Example: Betelgeuse.
• Blue Stars: These are the hottest stars with the highest temperatures (e.g., 11,000°C). Example: Rigel.
• The Sun: A yellowish-white star that falls between the temperatures of blue and red stars.

The Moon and Gravitational Forces

• The Moon rotates on its axis and also revolves around the Earth.
• Gravitational force: The force of attraction between all masses in the universe.
• This force keeps all planets orbiting the Sun.
• The theory is that the Moon once crashed into the Earth and then became the Moon.

Motion in the Solar System

Copernicus proposed that the planets revolved around the Sun (heliocentric model).

Earth's Tilt and Seasons

• Earth's rotational axis is tilted at 23.5 degrees from the vertical.
• This tilt affects the average daytime temperature.
• The Northern and Southern Hemispheres experience four seasons according to the tilt of the Earth.

Solstice and Equinox

When Earth's axis is most inclined toward or away from the Sun, it is called a solstice. Solstices occur twice each year: June 21 and December 21.

Between the solstices are the equinoxes, where hours of daylight equal the hours of darkness:

• Vernal Equinox: March 21
• Autumnal Equinox: September 21

Precession: Earth's Wobble

Precession: The changing direction of Earth's axis. Earth's axis wobbles and traces a circle every 26,000 years.

Lunar Cycles and Eclipses

Phases of the Moon

There are eight phases of the Moon in a lunar cycle that occurs over several weeks.

Eclipses

An eclipse is a darkening of a celestial object due to the position of another celestial object.

Tides: The Pull of the Moon

Tides are the rising and falling of the surface of large bodies of water caused by the interaction between Earth, the Moon, and the Sun.

Space Exploration and Technology

• Spacecraft: A robotic or human-occupied vehicle used to explore space and celestial objects.
• Some spacecraft are used to explore low Earth orbits.
• International Space Station (ISS): A research lab in low orbit.