Solar System

The Sun Closest star to Earth Yellow star Medium in size compared to the other stars About 4.6 billion years old More than 1 million Earths could fit inside it Central body of our solar system Main source of energy for Earth Essential to life on this planet

Energy from the Sun Made mostly of hydrogen and helium The Sun’s energy comes from nuclear fusion Nuclear fusion – changes hydrogen to helium Only one-fourth as dense as Earth (Earth is a rocky planet) Temperature on surface is 5,500 degrees Celsius (9,932 Fahrenheit) Temperature at the core about 15,000,000 degrees Celsius

The Sun’s Effect on Earth’s Energy Sun is the main source of energy on Earth Solar radiation provides heat to keep Earth warm and livable Ocean and atmosphere help moderate temperatures

The Sun’s Effect on Earth Food Photosynthesis – plants use sunlight to produce food (producers) When a consumer eats a plant the energy is transferred to the animal The sun is the energy source for nearly all living things

The Sun’s Effect on Earth Winds Winds form because of the sun Winds blow from regions of high air pressure to low air pressure Differences in air pressure form because of the Sun’s uneven heating of Earth’s surface

The Sun’s Effect on Earth Water Cycle Drives the water cycle Causes water on Earth’s surface to evaporate

Life Cycle of a Star Nebula - All stars start from enormous rotating clouds of dust and gasses – mostly hydrogen Protostar – the nebula collapses into a very dense mass Main-Sequence Star – When a newly formed star stabilizes, this stage can last billions of years, our Sun is in this stage

Life Cycle of a Star Red Giant – the outer part expands while the core contracts, becomes very bright but cools Planetary Nebula – the outer layers are released White Dwarf – over a long period of time the star shrinks, there is no fuel left in its core Black Dwarf – remaining heat radiates into space until it fades to a black dwarf

Life Cycle of a Star

Planets – large bodies that orbit the Sun Galaxy – a huge system of gas, dust and stars Our solar system is a very small part of a much larger system called the Milky Way galaxy

Moons Moon – a natural satellite orbiting around another body in space About 140 moons in our solar system Earth’s Moon Diameter of 3,476 km – four times smaller than Earth Rotates on an axis and revolves around Earth One month for the Moon to make a complete rotation Reflects the light from the sun Phases are produced by the alignment of the Moon and the Sun in the sky.

Phases of the Moon

Asteroids Relatively small, rocky object that orbits the sun Most orbit in a band called the asteroid belt between Mars and Jupiter

Comets A small, orbiting body made of dust, ice, and frozen gases. When a comet approaches the sun, frozen solids vaporize Gases and dust are released, producing a glowing region called a coma Charged particles push out of the coma, producing a glowing tail Some comets can take 30 million years to orbit the Sun

Meteoroids/Meteors Meteoroids – bits of rock or metal that orbit the sun Meteor – a meteoroid that enters Earth’s atmosphere and is heated by friction with the air For a few moments, they burn as they fall, appearing as streaks of light against the sky Also called falling/shooting stars

Inner Planets Mercury Venus Closest to sun, extremely hot (800 degrees) and cold (-343 degrees) Cratered surface due to collisions with asteroids Venus Second planet from the sun Covered by thick, poisonous clouds Pressure would crush your bones Almost the same size as Earth Temperatures hot enough to melt lead

Inner Planets Earth Only planet known to have liquid water Largest inner planet Mars Red planet, may have once had liquid water

Inner Planets Mars Photo from Mars Rover Earth Venus Mercury

Outer Planets Jupiter Fifth planet from the sun One of the brightest object in the sky Winds can reach up to 400mph Famous for its Great Red Spot – storm system Has many moons and rings Saturn Sixth planet from the sun Known for its rings – made mostly of ice particles Least dense - Saturn would float in water

Jupiter Saturn

Outer Planets Uranus Seventh plant from the sun Has at least 27 moons and 11 rings Neptune Eighth planet Winds can reach 1,500 mph At least 11 moons Pluto Classified as a dwarf planet in 2006 3 moons

Gravity Gravitation is an attractive force between objects that have mass It is weak unless the masses involved are very large (like Earth) Gravity causes objects to speed up as they fall Acceleration due to gravity at Earth’s surface is about 9.8 meters per second per second Air resistance, or drag, will slow a falling object

Planets Orbiting the Sun Just like we are pulled to Earth because it has a greater mass than us – The sun has a greater mass than the Earth which pulls the planet keeping it in orbit around it

Astronomers Astronomer – a scientist who studies outer space Famous Astronomers Copernicus – reasoned that the sun is at the center of the solar system Galileo – the first person to use a telescope