Lecture Notes: Exploration of the Solar System and Celestial Bodies

Introduction to the Milky Way and Our Solar System

• Our galaxy is called the Milky Way.
• The bright light seen in space is our solar system.
• The solar system is composed of the Sun and 8 major planets.

Overview of the 8 Major Planets

Mercury

• Closest planet to the Sun with an 88-day long year.
• Visible from Earth in 2016.

Venus

• Second planet from the Sun and the hottest.
• High carbon dioxide levels trap heat.

Earth

• Unique for supporting life due to suitable climate, landforms, and water.
• Moon is Earth's natural satellite.

Mars

• Known as the Red Planet due to its reddish appearance.
• Has large dust storms covering the planet for months.

Jupiter

• Largest planet and has four moons.
• Shortest day at approximately 9 hours 55 minutes.

Saturn

• Features about 150 moons with Titan as the largest.
• Known for its rings made of dust and ice.

Uranus

• Extremely cold with temperatures of around -224°C.
• Takes 84 Earth years to orbit the Sun.

Neptune

• Known as the Ice Giant.
• Takes 165 Earth years to orbit the Sun.

Dwarf Planets in the Solar System

• Ceres, Pluto, Eris, Makemake, and Haumea.
• Jupiter’s moon Ganymede has more water than Earth.

Formation of the Solar System

Origins and Process

• Formed 4.6 billion years ago from a cloud of dust and gas disturbed by a supernova.
• Gravity caused matter to clump together forming the solar nebula.
• Sun formed from the center of this nebula as a powerful new star.

Planetary Formation

• Inner planets (Mercury, Venus, Earth, Mars, Jupiter) formed in the hotter center.
• Outer planets (Saturn, Uranus, Neptune) formed in cooler edges.

The Sun

Importance and Structure

• Holds the solar system together with gravity.
• Composed mainly of hydrogen (91%) and helium (8.9%).
• Temperature at the surface is about 5,600°C.

Life Cycle

• Will last another 6.5 billion years before becoming a red giant, then a white dwarf.

The Moon

Formation Theories

• Capture Theory: Moon was captured by Earth's gravity.
• Accretion Theory: Formed alongside Earth.
• Fission Scenario: Part of Earth broke away to form the Moon.
• Giant Impact Theory: Most accepted, involving a collision between proto-Earth and Theia.

Formation of Earth

Big Bang to Formation

• Universe began with the Big Bang around 13.8 billion years ago.
• Earth formed about 4.5 billion years ago from cosmic debris.

Development

• Initial hot, molten state cooled over time.
• Formation of crust and Pangaea through volcanic and tectonic activity.

Pluto's Reclassification

Planetary Criteria by IAU

• Must orbit the Sun, be spherical, and clear its orbit of other objects.
• Pluto fails the third criterion, hence classified as a dwarf planet.
• Other dwarf planets include Haumea, Makemake, and Eris.

Trivia

• Pluto was named by an 11-year-old girl, Venetia Burney.
• It features ice volcanoes and an ocean beneath its surface.

Conclusion

• This lecture explored various aspects of our solar system, the formation of celestial bodies, and current scientific understanding of these entities.