Science guide test 2 - 4 BIM

Lesson 1: Solar System Objects

  • Solar System: Consists of the sun, planets, their moons, and smaller objects orbiting the sun, held in place by gravitational pull.

  • Gravitational Force: Depends on mass and distance between objects.

Distances in the Solar System

  • Astronomical Unit (AU): Unit measuring distance from Earth to the sun (1 AU = 150,000,000 km).

Comparing the Sun and Planets

  • Sun: Gaseous, mid-size star, accounts for 99.85% of solar system's mass.

  • Planets:

    • Round and orbit the sun.

    • Inner Planets (Mercury, Venus, Earth, Mars): Smaller, composed of rocks and metals.

    • Outer Planets (Jupiter, Saturn, Uranus, Neptune): Larger, composed of gas and liquid.

Differences between Sun and Earth

  1. Earth is a planet; Sun is a star.

  2. Sun is larger than Earth.

  3. Earth is mostly rock; Sun is mostly gas.

Smaller Solar System Objects

  1. Dwarf Planets: Spherical objects that haven't cleared their orbit (e.g., Pluto, Eris).

  2. Moons: Natural satellites orbiting planets, held by gravity (e.g., Earth has 1, Jupiter and Saturn have over 60).

  3. Asteroids: Small, rocky bodies (e.g., Ida).

  4. Meteoroids: Chunks smaller than asteroids; meteors are the light produced upon entry into Earth's atmosphere; meteorites hit Earth's surface.

  5. Comets: Icy and rocky bodies with long, narrow orbits.

Structure of the Sun

  • Composition: ¾ hydrogen, ¼ helium.

  • Core: Site of nuclear fusion (hydrogen to helium).

  • Radiative Zone: Gamma rays emitted, heat flow as electromagnetic waves.

  • Convection Zone: Heated and cooled plasma creates convection loops.

  • Photosphere: Visible part of the sun.

  • Chromosphere: Produces color.

  • Corona: Outer layer, appears as a halo.

Features of the Sun

  1. Sunspots: Dark areas caused by cooler plasma.

  2. Prominences: Loops of plasma following magnetic fields.

  3. Solar Flares: Explosive energy releases from sunspot regions.

Inner Planets (Terrestrial)

  • Mercury: Smallest, heavily cratered, no atmosphere; extreme temperature differences.

  • Venus: Similar size to Earth, thick sulfuric acid clouds; volcanic activity.

  • Earth: Supports life, liquid water, one moon.

  • Mars: Known as the Red Planet; evidence of past water and ice caps.

Composition Comparison

  • Mercury: None

  • Venus: Carbon dioxide and sulfuric acid clouds

  • Earth: Nitrogen, oxygen, trace gases

  • Mars: Mainly carbon dioxide with nitrogen and argon.

Outer Planets (Gas Giants)

  • Jupiter: Largest, no solid surface, features storms and the Great Red Spot.

  • Saturn: Known for its extensive rings of ice and dust.

  • Uranus: Rotates on its side, methane in its atmosphere gives it a light green color.

  • Neptune: Windy, appears blue due to methane.

Composition of Gas Giants

  • Jupiter: Mostly hydrogen, some helium.

  • Saturn: Mostly hydrogen, some helium.

  • Uranus: Hydrogen, helium, a little methane.

  • Neptune: Hydrogen, helium, a little methane.

Solar System Formation

  • Formed 4.6 billion years ago from a cloud of hydrogen, helium, rock, and ice.

  1. Gravity pulled materials together forming a cloud.

  2. High temperature and pressure fused hydrogen into helium, forming the Sun.

  3. Rock and ice combined to form planetesimals.

  4. Collisions formed the inner planets.

  5. Outer planets formed in cooler environments.