Geosciences
Safwan
Lec4_SolarSystem.pptx
Timing is important: 14 billion for Big Bang event, then various ages for galaxies (10-13.6 bill)
But how old is our solar system?
Our Solar System = The planets, their moons, the Sun, the Asteroid belt, Meteorites
When and how did our solar system form?
The Big Bang Theory describes how the universe formed, NOT our solar system.
The Big Bang is the EVENT that began the rapid expansion that led to our universe
Scale is important! If the Sun were hollow, about 1 million Earths could fit inside it!
Solar System Formation
Inner versus Outer planets
Temperature and planet formation
Meteorites
Our Solar System The Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, Comets, Meteorites, Asteroids, planetary satellites (moons)
What is wrong with this diagram?
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😫The sun is the wrong size (relative to the planets)
😫 The planets are not shown at their true size
😫 It is not to scale
😫 The distance between the planets is not shown correctly
How much of our solar system, in terms of total mass, does the Sun represent?
30%
50%
80%
99%
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Solar System: Sun
Clouds of gas (H & He) & dust pulled together by gravity
Stars use hydrogen as fuel
Very high T/P
Fuses hydrogen atoms – nuclear fusion – to form helium
Clouds of hydrogen gas and dust in Eagle Nebula are incubators for the formation of new stars.
Question – where did the H and He come from?
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Solar System Formation
Gas & dust pulled together by gravity rotating disk
Star & planets form at the same time (4.6 Ga = billion years ago)
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Inner vs Outer Planets Terrestrial Jovian (AKA Gas Giants)
4 Terrestrial planets: Mercury, Venus, Earth, Mars
Eight Planets:
4 Jovian planets: Jupiter, Saturn, Uranus, Neptune
(Note Change of Scale)
A question scientists might ask: why are the inner and outer planets so different?
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This gives a slightly better view…
Terrestrial
Jovian
WHY?
Rocky Inner Planets v. Gaseous Outer Planets (workbook/handout)
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What does this graph show?
If you don’t know where to start, look at the axes!
X-Axis=AU
Astronomical Unit
1 AU = distance between earth and sun = 93 million miles.
Y-Axis=Kelvin
255 Kelvin = 0 F
AU = Astronomical Unit. Roughly the distance between the Earth and the Sun.
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Temperature and Planet Formation:
What would happen if the gaseous planets were moved in closer to the sun?
Temperature is key.
What is the effect of solar heat on gases?
What about the effect of solar heat on rocks?
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Solar System: Other (asteroids, meteorites)
Asteroid: Small (> 100m), planet-like body, mainly between Mars & Jupiter – left over from solar system formation
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NASA has a group that watches these. There are over 1200 potentially hazardous asteroids that pass near earth each year.
Meteorites formed at the same time as everything in our solar system. They tell us something about Earth…
Meteorite: Remains of meteoroids found on Earth.
Fall to Earth ~40k tons/yr
All formed at the time the solar system formed:
Type Number Dated Method Age (billions of years)
Chondrites (undisturbed H, LL, E) 38 Rb-Sr 4.50 +/- 0.02
H Chondrites (undisturbed) 17 Rb-Sr 4.52 +/- 0.04
H Chondrites 15 Rb-Sr 4.59 +/- 0.06
LL Chondrites (undisturbed) 13 Rb-Sr 4.49 +/- 0.02
E Chondrites (undisturbed) 8 Rb-Sr 4.51 +/- 0.04
Eucrites (polymict) 23 Rb-Sr 4.53 +/- 0.19
Eucrites 13 Lu-Hf 4.57 +/- 0.19
Iron (plus iron from St. Severin) 8 Re-Os 4.57 +/- 0.21
What do you notice about all the measured ages?
Reproducibility and Repeatability = Precision!
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SCALE IS IMPORTANT!
Relative Sizes in the Universe (workbook/handout)
Sun’s diameter: 865,370 miles
--> 7,917 miles
How many Moons can fit across Earth’s diameter? In other words…Earth is how many times as big across as the Moon? ESTIMATE!!!
Look at the diameters above – you DON’T need a calculator = ROUND the numbers...
How many Earth’s can fit across Sun’s diameter? (i.e., the Sun is how many times bigger across than the Earth?). Again…rough estimate it!
Turn in workbook activities (handout) for participation credit. Make sure your NAME is legible on all pages.
