OUR SOLAR SYSTEM James Martin Facebook.com/groups/AstroLSSC Twitter.com/AstroLSSC
It s time for the human race to enter the solar system. -Dan Quayle
Structure of the Solar System Our Solar System contains a star, planets, dwarf planets, and other objects! Orbits of the planets are within a few degrees of each other and move in the same direction around the Sun
The Sun Sun s energy comes from nuclear fusion within its core A star s temperature determines its color Coldest stars are red (as low as ~1,000 o F) Hottest stars are blue (as high as ~62,500 o F) Our Sun s surface temperature = ~10,000 o F
Defining a Planet A planet is defined as a celestial body that: Orbits the Sun Is nearly spherical due to its own gravity Travels along an orbital path free of most debris Dwarf planets meet the first two conditions only
Planet Sizes & Compositions Inner Planets Terrestrial planets composed of rocky materials with dense iron cores and high average densities Outer Planets Jovian planets composed primarily of lighter elements, such as H and He, with low average densities
Mercury Revolution period of 88 days Extreme temperature fluctuations ranging from 800 o F to -270 o F No moons
Venus Thick CO 2, H 2 0 and H 2 SO 4 (sulfuric acid) atmosphere traps sunlight and broils the planet s surface Maximum surface temperature reaches up to 900 o F Revolution period of 225 days, but one rotation is 243 days In other words, 1 day on Venus is longer than 1 year! No moons
Earth Only planet known to support living organisms 71% surface is composed of water Oceans help to maintain stable temperatures O & Nitrogen rich atmosphere is layered trap sunlight to heat the surface (greenhouse effect) One Moon orbits Earth
Water on Mars! Mars Most water is frozen in the polar caps or as subsurface permafrost Subsurface liquid water recently discovered Appears red due to iron oxide (rust) in its soil One revolution takes about 2 yrs 2 moons orbit the planet
Jupiter Great Red Spot is a complex storm raging for the last ~400 years Largest and most massive planet Diameter is 11x bigger than that of Earth s One revolution takes about 12 years Composed mostly of H and He 67 known moons! Io and Europa over Jupiter disk
Mostly composed of H and He Complex ring structure A-G Saturn Only A, B and C rings can be readily seen from Earth! Rings are less than 1 mile thick, but extend to ~ 260,000 miles from the surface One revolution takes ~30 years 62 known moons!
Uranus Bluish color is a result of methane in the atmosphere (absorbs red and green light) One revolution takes ~84 years Cloud top temperatures measured to be about -350 o F over most of the planet Planet is tilted 60 o and appears to rotate on its side 5 known moons
Neptune Also blue due to methane in the atmosphere One revolution takes ~165 years Several large storm systems similar to Jupiter s G.R.S. Great Dark Spot is the size of Earth! Fastest winds in the solar system (~1200 mph) 14 known moons
Dwarf Planets Video: What is a dwarf planet?
Asteroids Asteroid sizes range from 100m to about 1000km 100,000+ rocky objects within the orbit of Jupiter (2-3.5 AU) Orbit the Sun in the same direction as the planets
Meteoroids Interplanetary rocky material smaller than 100m (down to grain size) Called a meteor as it burns in Earth s atmosphere If it makes it to the ground, it is a meteorite Most meteor showers are the result of the Earth passing through the orbit of a comet which has left debris along its path
Trans-Neptunian Objects 1,000+ small bodies orbiting beyond Neptune in the same direction as the planets Most are in the Kuiper Belt at 30-50 AU Pluto orbits at an avg. 39 AU!
Comets Kuiper Belt collisions cause fragmented objects to change orbits Sun s radiation vaporizes ices, producing gas and dust tails Some comets from the Oort Cloud (~50,000 AU)
Scale of the Solar System
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