The Solar System Earth Science Solar System 20

The Solar System Earth Science: Solar System (20 min)

The Solar System • Matter that forms a system and shares a gravitational force with the sun = solar system. – The sun, planets and all objects that revolve around the sun make up our solar system. – Extensive and covers a large territory – Energy, from the sun, is in the form of radiation as infrared waves.

Solar System Models • Greek astronomers (A. D. 140) watched stars move across the sky and charted their unchanging patterns. – Noticed 5 points of light wandered among the stars – planets • Planet = Greek for “Wandering Star” – Ancient Romans named these 5 planets Mercury, Venus, Mars, Jupiter and Saturn. – Believed that Earth is at the center of the solar system – Geocentric system • Geo = Greek for “Earth”

Solar System Models • Polish astronomer Nicolaus Copernicus (1500 s) believed the sun to be the center of the solar system - heliocentric system. – Helios = Greek for “sun” • Galileo Galilei (1500 -1600 s) defended this idea with two discoveries: 1. Jupiter has 4 moons revolving around it. • Not everything in the universe revolves around Earth. 2. Venus goes through phases similar to Earth’s moon. • This couldn’t happen with Earth being at the center.

Inertia and Gravity • The planets revolve around the sun in a curved path, orbit. – What forces keep the planets in their orbits? Inertia and Gravity • The ability of an object to continue in a straight line or remain stationary = inertia. – Increase mass = increase inertia • The force that attracts all objects toward each other = gravity – Mass and distance both affect gravity.

Gravitational pull of sun. Planet’s Velocity

The Sun • Came into being about 4. 6 billion years ago • Center of the solar system. • The sun’s gravity is by far the most powerful force in the solar system. • All objects revolve around the sun. • Contains 99. 8% of the mass of the solar system • Mostly Hydrogen (H) and Helium (He) – Uses nuclear fusion to convert hydrogen into helium • Will last for 10 billion years and is estimated to be 5 billion years old right now. • Burns at 15 million °C

The Planets • There a total of 8 planets that make up our solar system: – Mercury – Venus – Earth – Mars – Jupiter – Saturn – Uranus – Neptune Inner Planets: Terrestrial Planets Outer Planets: Gas Giants

Inner Planet Characteristics • • • Closest to the sun Composed mostly of rock Small and Dense Few to no moons No rings Mercury Mars Venus Earth

Inner Planet Facts Planet Mercury Venus Earth Mars Diameter Rotation (km) (Earth days) 4, 878 12, 104 12, 756 6, 794 59 243 1 1. 03 Distance Revolution Moons from the (Earth Sun years) (km) 58, 000. 24 0 108, 000. 62 0 150, 000 1 1 228, 000 1. 9 2

Mercury • First planet closest to the sun • Second smallest planet • Thin to no atmosphere – Due to the planets extreme temperature the atmosphere heated to the point that it escaped. • Most extreme temperatures of all the planets – Day time = 430°C – Nighttime = -170°C

Venus • Second planet from the sun. • Similar to Earth in size and mass and is referred to as Earth’s twin. • Also known as the “evening star” or “morning star” – Shines bright in western sky • Atmosphere is thick and dense consisting mostly of carbon dioxide (CO 2) and sulfuric acid (H 2 SO 4) • Temperature is roughly 460°C

Earth & Mars Earth • Third planet from the sun. • Is the only planet where life exists at present time due to oxygen and liquid water. Mars • The fourth planet from the sun. • Called the “red planet”. • Thought to once have running river systems. • Has a thin atmosphere and clouds.

Outer Planet Characteristics • Farthest from the sun. • Composed mostly of gas - “gas giants”. • Large in size - make up 99% of the mass of the celestial bodies that orbit the sun. • Several moons. • Separated from the inner planets by an asteroid belt.

Outer Planet Facts Planet Jupiter Diameter Rotation Distance from Revolution Moons (km) (Earth the Sun (Earth days) (km) years) 142, 800. 41 778, 000 12 18 Saturn 120, 540 Uranus 51, 200 Neptune 49, 500 . 43. 72. 67 1, 427, 000 2, 871, 000 4, 497, 000 29 84 165 18 20 8

Jupiter • Fifth planet from the sun. • Largest planet in the solar system. – 300 times bigger than Earth. • Consists mostly Hydrogen (H) and Helium (He) • Known for its “Great Red Spot”, a storm similar to a hurricane.

Saturn Sixth planet from the sun. Second largest planet Known for its over 1000 rings Consists mostly of Hydrogen (H) and Helium (He) • Least dense of the planets – less dense than water (1 g/m. L). • •

Uranus & Neptune Uranus • The seventh planet from the sun. • Looks blue due to its traces of methane and ammonia. • Axis is tilted at 90° making it look like it rotates on its side, or from bottom to top. Neptune • The eighth and farthest planet from the sun. • Extremely fast winds, 1200 mi/hr • Looks blue due to its traces of methane and ammonia.

What about Pluto? ? ? • Pluto is no longer considered the ninth planet of our solar system but is now called a dwarf planet. • Definition of a planet: an object that orbits the sun and is large enough to have become round due to the force of its own gravity. In addition, a planet has to dominate the neighborhood around its orbit. – Pluto does not dominate its neighborhood and has an untidy orbit.

Other Celestial Objects • Three other celestial objects can be found in our solar system besides the sun, moons and planets: – Comets – chunks of ice and dust whose orbits are usually very long and narrow ellipses. • Unique in that they have long tails that trail behind the comet itself. – Halley’s Comet, 1986 » 76 yr orbit = 2062 will be its next sighting. – Hale-Bopp, 1997

Other Celestial Objects – Asteroids – too small and too numerous to be considered planets • Revolve around the sun between Mars and Jupiter in the asteroid belt.

Other Celestial Objects – Meteoroid – A chunk of rock or dust in space. • Usually come from comets or asteroids when they break apart. – Upon entering Earth’s atmosphere friction make a meteoroid burn up and produce a streak in the sky = meteor. » If a meteor doesn’t burn up completely and hits Earth’s surface it is called a meteorite. • Consist mostly of iron (Fe) and nickel (Ni).

Chicxulub Crater, Yucatán Mexico

10 Biggest Asteroid Impacts