14. What do we need for life on Earth?
• The right chemical elements
Oxygen Hydrogen
Carbon Iron
Silicon Nitrogen
Calcium
15. What do we need for life on Earth?
• The right chemical elements
Oxygen Hydrogen
Carbon Iron
Silicon Nitrogen
Calcium
16. What do we need for life on Earth?
• The right chemical elements
• Liquid water
17. What do we need for life on Earth?
• The right chemical elements
• Liquid water
• The right temperature range
0 - 100 Celsius
18. What do we need for life on Earth?
• The right chemical elements
• Liquid water
• The right temperature range
• An atmosphere
shields planet
traps heat
19. What do we need for life on Earth?
• The right chemical elements
• Liquid water
• The right temperature range
• An atmosphere
• Enough gravity
20. What do we need for life on Earth?
• The right chemical elements
• Liquid water
• The right temperature range
• An atmosphere
• Enough gravity
• Volcanic activity
21. What do we need for life on Earth?
• The right chemical elements
• Liquid water
• The right temperature range
• An atmosphere
• Enough gravity
• Volcanic activity
...The ‘Habitable’ Zone!
49. atmosphere
of CO2
in habitable zone
T range -127 to 17oC
water
water vapour
in ice caps
in craters
dry river beds
50. atmosphere
of CO2
in habitable zone
T range -127 to 17oC
water
water vapour
in ice caps
in craters
dry river beds
51.
52.
53.
54.
55.
56.
57.
58. Methane on Mars
• Plumes of methane mean something has to
be generating methane
• Source = subsurface -- geological or
bacterial?
• http://www.nasa.gov/mission_pages/mars/
news/marsmethane.html
74. Titan
• Thick methane
atmosphere with lots of
Nitrogen.
• Only other nitrogen
domiated atmosphere
except Earth
• May be pre-biotic
atmosphere, like early
Earth.
• Lakes of methane--good
organic solvent.
77. Exoplanets
Planets around stars other than our Sun in our galaxy,
the Milky Way ... about 500 so far!
detect by transit
detect by imaging
detect by radial velocity
August 2010
78. Detection Methods:
radial velocity
• Star moves because of
planet’s gravity pull
• Measure motion of star
along our line of sight to
get period of orbit
79. Detection Methods:
transit
• Planet moves in front of star during its orbit
• Light from star is dimmed because planet is
in front of it
80. Detection Methods:
direct imaging
• Take a picture of a planet around a star
• Hard to do because planets are faint and
stars are bright
81.
82.
83. Hot Jupiters
• Most extrasolar planets we have found are
“hot Jupiters”
• Most are 1 to 13 x Mass of Jupiter
• Most are located 10 x closer to their star
than Earth
• Most are around Sun-like stars (because
they are easily observed using radial
velocity)
84. Hot Jupiters
• Most extrasolar planets we have found are
“hot Jupiters”
• Most are 1 to 13 x Mass of Jupiter
• Most are located 10 x closer to their star
than Earth
85. Hot Jupiters
• Most extrasolar planets we have found are
“hot Jupiters”
• Most are 1 to 13 x Mass of Jupiter
• Most are located 10 x closer to their star
than Earth
• Most are around Sun-like stars (because
they are easily observed using radial
velocity)
• Densities are very different
86. Earth-like Planets
• Kepler Telescope lets us look for Earth-mass
planets in the habitable zone of other stars
• Also finds “super Earths” which are 1 to 10x
mass of Earth but are not gas balls
• More common than Jupiter-mass planets but
VERY new area of research
87. Earth-like Planets
• Are any of these planets actually like Earth?:
– Air, water, rocks, life, etc?
• Could we visit one of these planets?
– How? Why or why not?
• Could we communicate with one of these
planets?
– Have we tried already? How would we identify
communication from another planet?