Download 406P PPT - Why Water and the Hunt for Exoplanets

Extremophiles
Live in harsh conditions we used to think
could not possible support life:
Extremophiles
– lining the rim of a pitch-black, deep sea
volcanic vent
Extremophiles
– can living in steaming hot springs
Extremophiles
–frozen in ice in an Antarctic lake.
Halophilic Bacteria, Atacama Desert
– or feeding off salt in the sands of the driest
desert on Earth.
Life can handle dark, hot, cold, and
salty, but it absolutely must have…
Liquid
Water…
…Is essential to
life
Kangaroo Rat vs. Salmon
• Have same % of water
content in cells (50 – 65 %)
• Same % of salt in cells
• (about 1 % on average)
• 1/3 of salt in sea water
(about 3.5 % on average)
Frost Line
Outside the frost line, water freezes into ice.
Closer to the sun, water is vaporized into steam.
Habitable Zone
The region of
the solar
system where
temperatures
allow water to
exist in its
liquid state.
Its nickname is the “Goldilocks Zone”.
o
Venus-(800 F) -
Too Hot!
o
Mars (-67 F) - Too Cold
Mars
•Water is
frozen.
•Ice caps
even have
dry ice
(frozen CO2).
Earth - The “Blue” Planet “Just Right”
Earth lies right in the middle of our solar
system’s habitable zone.
Only Earth has
liquid water. (and it
covers ¾ of it
surface!!)
Water Vapor (Gas)
Solid Water
(Ice)
Liquid Water
On Earth, water exists in
three physical states:
Liquid Water…
…Is essential to
life
Possibilities
for Space
Colonies
Europa
•Moon of Jupiter
•Water is frozen
into ice.
•May have a
thick mantle
zone of liquid
water below the
ice
Titan
Possibilities
for Space
Colonies
• Moon of
Saturn
• Only moon
with an atmosphere
• Surface water is
frozen
• May have a thick
mantle zone of liquid
water and ammonia
below the ice
Habitable Zone of Another Solar System
The region of a solar
system where
a
temperatures allow
water to exist in its
(Red Dwarf
0.3 M ‫)סּ‬
liquid state.
1 Pegasi B, or Bellerophon • First exoplanet discovered orbiting
around a star - found in 1995.
• Its parent star, 1 Pegasi is:
• about 48 ly (light years) away
• Slightly bigger and brighter than the
Sun (1.1 Mʘ , 1.3 Lʘ)
• Gas giant – “Hot Jupiter”
• ½ the mass of Jupiter
• 30% larger diameter than Jupiter
• Extremely close to its sun - just 5
million miles out (.05 AU)
1 Pegasi B, or Bellerophon • 20X closer to its star than the Earth is
to the Sun, so much hotter than Jupiter
• (Gas giants are NOT supposed to be
that close to their sun!!)
• Takes about 4 days to orbit its sun.
• Really hot there (1300 K) hot enough
to vaporize the nickel and give the
planet a bluish tint.
• It may be tidally locked, so the same
side is always facing its sun.
• NOT habitable!! – way too hot!!
Possibilities for Space Colonies
Ammonia – Another Polar Solvent
• Ammonia (NH3) is
a polar molecule
just like water.
• Ammonia has just
one lone pair of
electrons.
• Water has much
stronger H-bonds,
so it is harder to
vaporize and
more likely to be a
liquid at Earth
temperatures
(Oo C to 100o C)
AMMONIA
Ammonia – Another Polar Solvent
• H-bonds between
ammonia molecules
are much weaker
than the H-bonds
between water
molecules.
• As a result, ammonia
vaporizes to a gas
much more easily.
AMMONIA
Ammonia – Another Polar Solvent
• For a planet to
have ammoniabased life forms,
the temperature
would need to be
down around
-33o C to -78o C!
• Where does it get
that cold?
• Maybe on Titan??
AMMONIA
Titan
Possibilities
for Space
Colonies
• May have a
mixture of liquid
water and
ammonia in its
mantle
• has surface
pools of liquid
hydrocarbons
(ethane &
methane)