View
216
Download
0
Category
Tags:
Preview:
Citation preview
Life in our Solar SystemLife in our Solar System
What is the definition of ‘Life’?What is the definition of ‘Life’?
“A collection of molecules that can undergo metabolism, be able to grow, respond to stimuli, reproduce, and adapt to their environments through natural selection.”
Formation of EarthFormation of Earth
• Earth was formed ~4.5 Billion years ago from smaller planetesimals crashing together.– Giant impact forms Moon ~4.4 Billion years ago– Earth continually bombarded by giant impactors
until 3.8 Billion years ago
Life on EarthLife on Earth
• Life appears on Earth soon after heavy bombardment ends in the form of marine fossils
• Oldest fossil 3.5 Billion years
Life of EarthLife of Earth
• Activity stays quiet until large amounts of stromatolite fossils found between 2.7 Billion years ago and 540 Million years ago
• Caused by sudden appearance of oxygen
Life on EarthLife on Earth
• ~540 Million years ago, sudden appearance of animals during Cambrian explosion– Nearly complete disappearance at ~500 My ago
Life on EarthLife on Earth
• 500 My - 250 My: animals getting substantially larger– Sharks, amphibians, reptiles
• 250 – 65 My: Age of the dinosaurs• 65 My – present: Age of the mammals– ~ 1 My ago: humans begin showing up
Requirements of LifeRequirements of Life
Think-Pair Share Activity:1.Water2.Access to appropriate raw materials3.Energy source (solar or chemical)
Helpful Conditions For LifeHelpful Conditions For Life
• Plate tectonics– Recycle nutrients– Allow for continents– Help maintain constant temperature
• Magnetosphere– Deflects dangerous radiation from Sun
• Atmosphere– Helps regulate temperature (carbon dioxide)– Contains oxygen (allows for large life forms?)
Life In Extreme EnvironmentsLife In Extreme Environments
We find microbes living in conditions of boiling water, low moisture (arid), ice, high acidity, high salt, no sunlight, and deep underground
Temp. Range of life on Earth: -5°F to 235°F
MercuryMercury
• Daytime temp: 800 °F• Nighttime temp: -300 °F• No liquid water• Magnetosphere less
than 1/1000 of Earth• No plate tectonics• No atmosphere
VenusVenus
• Daytime temp: 900 °F• No liquid water• Magnetosphere less than
1/1000 of Earth• Possible single plate surface• Thick carbon dioxide
atmosphere with surface pressure ~90 times Earth
MoonMoon
• Daytime temp: 225 °F• Nighttime temp: -245 °F• No liquid water (frozen water
in permanently shadowed craters)
• Within Earth magnetosphere• No plate tectonics• No atmosphere
MarsMars
Presently• Daytime temp: 0 °F• Nighttime temp: -180 °F• No liquid water found (frozen
water at the poles)– Possible underground water
• No magnetosphere• No plate tectonics• Thin atmosphere (1/100 of
Earth)
MarsMars
Past• Unknown temperatures• Liquid water at the surface• Strong magnetosphere• No plate tectonics• Thicker atmosphere (similar
to Earth)
Mars In DetailMars In Detail
Evidence for Past Water:1.Gullies
- Water flow down crater walls
Mars In DetailMars In Detail
Evidence for Past Water:1.Gullies2.Tributaries
- Caused by rain?
Mars In DetailMars In Detail
Evidence for Past Water:
1.Gullies2.Tributaries3.Flow Channels
- Carved by huge amounts of flowing water?
Mars In DetailMars In Detail
Evidence for Past Water:1.Gullies2.Tributaries3.Flow Channels4.“Blueberries”
Mars In DetailMars In Detail
Evidence for Past Water:1.Gullies2.Tributaries3.Flow Channels4.“Blueberries”5.“White powder”
- Pure silicon dioxide- Ancient hot spring?
JupiterJupiter
• Gaseous surface– Not solid
• Huge magnetosphere• High radiation environment
Jupiter’s MoonsJupiter’s Moons
Europa• Size of the Earth’s Moon • High radiation environment
at surface• Thin atmosphere• Evidence for water• Plate tectonics?• In Jupiter’s magnetosphere
Europa In DetailEuropa In Detail
Europa• Evidence points toward deep
subsurface ocean• Very thin atmosphere• Possible plate tectonics• In Jupiter’s magnetosphere
Jupiter’s MoonsJupiter’s Moons
Callisto• About the size of Mercury• Possible thin subsurface
ocean• Very thin atmosphere• No plate tectonics• In Jupiter’s magnetosphere
SaturnSaturn
• Gaseous surface– Not solid
• Large magnetosphere• High radiation
environment• Very similar to Jupiter
Saturn’s MoonsSaturn’s Moons
Titan• 1.5x size of the Moon• Possible thin subsurface
ocean• Thick atmosphere • Extremely cold (-290 °F)• Weathering and erosion
Titan In DetailTitan In Detail
Titan• Surface lander Huygen’s
probe• Atmosphere possibly similar
to ancient Earth’s• Methane lakes• Cryo-volcanism (volcanoes of
water)
Saturn’s MoonsSaturn’s Moons
Enceladus• 1/7 size of Earth’s Moon• Possible subsurface water
(cryo-volcanism)• No atmosphere • Extremely cold
Outer planetsOuter planets
• Uranus, Neptune, Pluto– Very, very, very cold– Likely no liquid water– No atmosphere– No plate tectonics
Recommended