Olympiad Notes: Earth and Universe | Science Olympiad Class 6 PDF Download

The Universe

• Definition and Scope: The universe encompasses everything known, including planets, stars, galaxies, and more.
• Age: It is approximately 13.8 billion years old.
• Composition: Comprises billions of galaxies, each containing billions or trillions of stars.
• Our Galaxy: We reside in the Milky Way galaxy, one among countless others in the universe.

The Solar System

• Components: Includes the Sun, eight planets, moons, asteroids, comets, and smaller objects.
• The Sun: Central to our solar system.
• Purpose of Study: Understanding the solar system sheds light on planetary formation and evolution, conditions for life, and celestial diversity.

The Planets

• Nature of Planets: Planets are celestial bodies orbiting stars, like Earth orbits the Sun.
• Number in Solar System: There are eight recognized planets in our solar system, each with unique characteristics.

Classification of Planets

Terrestrial Planets

• Composition: Composed of rocks and metals with solid surfaces.
• Location: Closer to the Sun.
• Examples: Mercury, Venus, Earth, Mars.

Jovian Planets

• Size: Larger than terrestrial planets.
• Composition: Mostly hydrogen and helium gases.
• Location: Farther from the Sun.
• Features: Possess rings and are similar to Jupiter.
• Examples: Jupiter, Saturn, Uranus, Neptune.

Dwarf Planets

• Definition: Orbit the Sun but are smaller and less influential gravitationally.
• Characteristics: Can be round or oddly shaped.
• Examples: Pluto, Ceres.

Planets in Our Solar System

Mercury

• Size: Smallest in our solar system.
• Orbital Characteristics: Closest to the Sun, fastest orbit.
• Surface and Moons: Rocky, no moons.
• Temperature: Extreme, uninhabitable.

Venus

• Comparison with Earth: Similar in size, but extremely hot with a toxic atmosphere.
• Rotation and Orbit: Slow rotation, orbits Sun faster than Earth.
• Surface: Solid, with volcanic features.
• Unique Rotation: Rotates backwards.

Earth

• Uniqueness: Only known planet with life.
• Size: Largest terrestrial planet.
• Surface and Moon: Dynamic surface, one moon.
• Atmosphere: Protects from meteoroids.

Mars

• Characteristics: Cold, desert-like, thin atmosphere.
• Rotation and Orbit: Similar day length to Earth, longer year.
• Surface: Rocky, red due to iron oxidation.
• Moons: Two, Phobos and Deimos.

Jupiter

• Size: Largest planet.
• Rotation and Orbit: Fast rotation, long orbital period.
• Nature: Gas giant, mostly hydrogen and helium.
• Moons and Rings: 95 moons, ring system.
• Notable Feature: Great Red Spot.

Saturn

• Distinguishing Feature: Prominent ring system.
• Nature: Gas giant.
• Moons: 146 moons.

Uranus

• Unique Rotation: Rotates on its side.
• Nature: Ice giant.
• Moons and Rings: 27 moons, 13 rings.

Neptune

• Location: Farthest from the Sun.
• Features: Cold, windy, 14 moons, ring system.
• Rotation and Orbit: Fast rotation, long orbital period.

Earth’s Movements

Rotation

• Definition: Earth's spinning around its axis.
• Consequence: Causes day and night, affects shadow length.

Revolution

• Definition: Earth's movement around the Sun.
• Impact: Results in different seasons.

Tilted Axis

• Nature: Axis is tilted, not upright.
• Effect: Causes seasonal changes due to varying sunlight exposure.