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The Solar System. 18.3 Objectives. Identify the planets of the solar system and their features Describe the formation of the solar system Explain eclipses and the phases of the moon. Vocabulary. Planet Solar system Asteroid Nebular model
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18.3 Objectives • Identify the planets of the solar system and their features • Describe the formation of the solar system • Explain eclipses and the phases of the moon
Vocabulary • Planet • Solar system • Asteroid • Nebular model • Phases • Eclipse
Objective 1: Identify planets and their features • Early astronomers have known about “stars” that didn’t move like other stars • These are the planets • Early models had the earth as the center of the universe – they were incorrect
The solar system • There are 8 planets, planets reflect light • Pluto is now considered a dwarf planet • Planets reflect light
Inner Planets • Rocky and small • A few have moons
Mercury • Small • Mercury spins slowly – 3 spins every 2 orbits • Side currently facing the sun reaches 397 C • Dark side reaches -170 C • No atmosphere, no water
Venus • Thick greenhouse cloudy atmosphere • Mostly carbon dioxide • High amounts of Sulfuric acid • 90 times atmospheric pressure of earth • Surface temperature over 425 C
Earth • Ideal for life • Large amounts of water, found in all three forms • Atmosphere moderates temperatures
Mars • We have had several robotic missions to mars • Mars has mountains larger than Mt Everest • It has ice in the polar icecaps • There are many features that suggest mars used to have flowing water • Thin, carbon dioxide atmosphere
Asteroid Belt • There is an asteroid belt separating the inner and outer planets • Thousands of small rocky pieces
Outer Planets • Jupiter, Saturn, Uranus, Neptune • Called Gas Giants • Do not have a solid surface • All have rings and moons
Jupiter • Largest planet in solar system • Larger than 1300 earths • Atmosphere is hydrogen, helium, methane, ammonia • Bands are jet streams • Red spot is a hurricane twice the size of the Earth – it has been there for hundreds of years
Saturn • Planet with most pronounced rings
Uranus and Neptune • Blue Giants • Thick gas atmospheres, mostly methane (makes them blue) • Both have lots of moons
All Planets • Orbit the sun • Have enough gravity to be spherical • Have cleared other objects from their orbital path • Pluto orbits in the Kuiper belt • So it’s not a planet
Pluto the Dwarf Planet • It was either make more planets or demote Pluto • There are currently 5 • Ceres is in the asteroid belt – between Mars and Jupiter • Eris, Makemake, and Haumea are at the edge of the solar system – like Pluto • Eris is the so-called 10th planet – it was briefly called Xena after the TV show character
Objective 2: how did the solar system form? • Most accepted explanation is the Nebular Model – it formed from a cloud of stardust • A rotating disk of stardust • Planets form from accretion – stuff slammed into each other and stuck • When the sun started glowing – lighter material was pushed out to the outer planets
Objective 3: Describe phases of the moon and eclipses • The moon orbits the earth • Sunlight reflects off of the moon • The moon appears in phases because we can only see the side that faces the sun
Eclipses • There is a difference between a solar eclipse and a lunar eclipse • They are named based on what gets blocked out • Solar eclipse blocks the sun • Lunar eclipse blocks the moon
Lunar Eclipse • The earth’s shadow crosses the moon • 3 types • Penumbral – can’t be seen by eye • Partial • Total
Total Lunar Eclipse turns moon red • The light that does reach the moon goes thru the earth’s atmosphere filtering the blue light out Without the earth’s atmosphere the moon would be black
Solar Eclipses • There are fewer than 70 total solar eclipses in a century • You must be in the right place to see a total solar eclipse – the next total solar eclipse visible in the US will be in August 2017 • They are worth the road trip!
The moon is slowly moving away from us – • If the moon’s diameter were 140 miles smaller – we would not have solar eclipses
Looking at earth during solar eclipse • You can see the corona during a solar eclipse