The Solar System

Interesting facts about the solar system: Traveling from the Sun to the edge of the solar system in an air plane would take 800 years. Light from the Sun reaches Earth in 8 minutes. Pluto in 5.5 hours The closest star to our solar system is 4 light years away! Eight planets, 176 moons, 5 dwarf planets (possibly hundreds more), 659,212 known asteroids, and 3,296 known comets The Sun makes up 99% of the total mass of the solar system.

Astronomical Unit 1 AU = 149,597,870.691 kilometers (93,000,000 miles) Definition: An Astronomical Unit is average distance between the Earth and the Sun. Why is it the mean or average distance? Answer: Because orbits are elliptical Jupiter is 5.2 AU’s away from the sun

Characteristics of the Inner Planets Solid rocky surface Have iron cores Impact craters Have tectonic features such as mountains and valleys

Mercury Diameter in miles: 3,030 Distance from sun : 0.39 AU’s Year : 88 earth days Spin (Length of day): 59 Earth days Temperature ranges: High 840 Fahrenheit 450 Celsius Low -275 Fahrenheit -170 Celsius Gravity: 38 % of earth Number of moons: 0 Other interesting facts: Closest to the sun. Greatest temperature difference of all the other planets. First spacecraft visit was Mariner 10 in 1973. Very thin atmosphere. Slightly larger than Earth’s moon.

Venus Diameter in miles: 7,521 Distance from sun in AU’s: .723 In miles: 67.2 million Year : 225 earth days Spin: 243 earth days (The day is longer than the year) Temperature ranges: High 900 Fahrenheit 480 Celsius Gravity (Compared to Earth) : 90 % of earth Number of moons: 0 Other interesting facts: One of only two planets that rotate clockwise. Very hot due to the greenhouse effect. Known as the evening “Star” because it is one of the first objects visible as the sun sets. Brightest planet.

Earth Diameter in miles: 7,926 Distance from sun : 1 AU In miles: 93 million Year (In Earth Days) : 365 Spin (Length of day in hours): 24 Temperature ranges: High 136 Fahrenheit 58 Celsius Low -128 Fahrenheit -89 Celsius Number of moons: 1 Other interesting facts: 73% of the surface is covered with water. Atmosphere is mostly made up of Nitrogen, Oxygen, Carbon dioxide- Nitrogen is a key component of DNA the molecule of life. Only planet that has liquid water. Has one large moon vs. many smaller moons.

Mars Diameter in miles: 4,220 Distance from sun in AU’s: 1.6 In miles: 141.6 million miles Year : 687 earth days Spin: 24.6 hours Temperature : High 70 Fahrenheit 20 Celsius Low -80 Fahrenheit -60 Celsius Gravity : .37 % of earth Number of moons: 2 Other interesting facts: Called the red planet because of all the iron in the soil. Has the highest mountain (Olympus Mons, 17 miles high) in the solar system. May have once had flowing water. Atmosphere is 95% CO2. Has seasons

Asteroid Belt Location: Between the orbits of Mars and Jupiter Distance from the sun: 2.2-3.2 AU’s 329- 478 million miles. Composition: Boulder sized and larger pieces of rock. Other interesting facts: Early in the life of the solar system, dust and rock circling the sun were pulled together by gravity into planets. But Jupiter kept a number of the pieces from coalescing into another planet. (space.com). Most meteors and meteorites that come to Earth originated in the asteroid belt.

The Outer Planets Characteristics: Composed mostly of H and He. Strong gravity due to their mass. Very thick atmospheres. Known as the gas giants (Except Pluto) All the gas planets have rings Rings are mostly ice but are also composed of rock and dust

Jupiter Diameter in miles: 88,846 Distance from sun in AU’s: 5.2 In miles: 483.8 million miles Year : 4,331 earth days Spin (Length of day): 9.9 hours Temperature : -234 Fahrenheit -145 Celsius Gravity (Compared to Earth) : 2.31 X Number of moons: 63 Other interesting facts: Famous for its great red spot (3x the size of earth). Largest planet. Winds in the atmosphere could reach 260 mph. Galileo used the four large moons as further evidence that the Earth was not at the center of the universe.

Saturn Diameter in miles: 74,894 Distance from sun in AU’s: 9 In miles: 890.7 million miles Year : 10,747 earth days Spin (Length of day): 10.7 hours Temperature ranges: -288 Fahrenheit Gravity (Compared to Earth) : 90% Number of moons: 60 Other interesting facts: Rings are made of ice and rock. Only about 164 feet thick! Saturn would be able to float on water

Uranus The Greek God of the sky Diameter in miles: 31,763 Distance from sun in AU’s: 19.2 In miles: 1.8 billion miles Year : 30,589 earth days Spin (Length of day): 17.2 hours Temperature ranges: -346 Fahrenheit -210 Celsius Gravity: .87% of earth Number of moons: 27 Other interesting facts: Tilted on its axis 90 degrees. Made mostly of methane. Discovered in 1781

Neptune Diameter in miles: 30,775 Distance from sun in AU’s: 30.1 In miles: 2.8 billion miles Year : 59,800 days Spin (Length of day): 16.1 hours Temperature ranges: -346 Fahrenheit -210 Celsius Gravity : 1.1 x earth Number of moons: 13 Other interesting facts: Fastest clouds in the solar system 1,550 mph. Neptune was predicted to exist by math rather than direct observation.

Pluto Diameter in miles: 1,485 Distance from sun in AU’s: 39.5 In miles: 3.7 billion miles Year : 90,588 earth days Spin : 6.4 earth days Temperature ranges: -400 Fahrenheit -218 Celsius Gravity: 0.06 % compared to earth Number of moons: 5 Other interesting facts: An 11 year old girl from England suggested the name. Pluto and its largest moon, Charon, orbit a point in space that lies between them. Similar to binary stars. Spins backwards. “New Horizons probe” sent to investigate Pluto carried the ashes of Clyde Tombaugh who discovered Pluto in 1930. Became a dwarf planet in 2006. If Pluto were in the same orbit as Earth it would have a tail like a comet.

So why isn’t Pluto a planet? Pluto and is now known to be just one example of a collection of objects on the outskirts of the solar system called the Kuiper Belt Astronomers estimate that there are at least 70,000 icy objects, with the same composition as Pluto, that measure 100 km across or more in the Kuiper Belt. According to the new rules, Pluto is not a planet. It’s just another Kuiper Belt object. In order to be considered a planet it must meet these requirements: It needs to be in orbit around the Sun – Yes It needs to have enough gravity to pull itself into a spherical shape –Yes It needs to have “cleared the neighborhood” of its orbit – No What does “cleared its neighborhood” mean? As planets form, they become the dominant gravitational body in their orbit. As they interact with other, smaller objects, they either consume them, or sling them away with their gravity Any object that doesn’t meet this 3rd criteria is considered a dwarf planet.

Kuiper Belt The Kuiper Belt is a disc-shaped region of icy bodies - including dwarf planets and comets beyond the orbit of Neptune. It extends from about 30 to 55 AU and is probably populated with hundreds of thousands of icy bodies larger than 62 miles across and an estimated trillion or more comets. The first Kuiper Belt Object was discovered in 1992.  (space.com)

Kuiper Belt and Ort Cloud

Eris Diameter in miles: 1,445 Distance from sun : 96 AU’s In miles: 9 billion miles Year : 561 earth years Spin : 25.9 hours Temperature: -390 F Number of moons: 1 Other interesting facts: Twice as remote as Pluto

Size comparison of planets

Size comparison of planets This slide shows the relative Sizes of the Largest Solar System Objects - in the following order (to scale): Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Ganymede, Titan, Mercury, Callisto, Io, the Moon, Europa, Triton, Eris, Pluto

Size comparison of planets compared to the Sun

100 Largest objects in the solar system