Transcript Our Habitable Earth

Our Habitable Earth:
What conditions allow Earth to support and maintain life?
List the basic requirements
for human survival:

What conditions allow Earth to support and
maintain life?
 Proximity to the sun
 Atmosphere
 Gravity
 Magnetic Field
 Liquid Water
Proximity to the Sun
How does proximity to the Sun contribute
to a planet’s temperature and ability to
support life?
Proximity to the Sun
 The “Habitable Zone” is the region around a star where it is
possible for a planet with the correct atmospheric pressure to
maintain liquid water on its surface
 The Earth resides in the “Habitable Zone” of our nearest
star…the sun!
 Too far and the planet would be too cold for liquid water; too
close and the planet would be too hot for liquid water.
 Living organisms require liquid water to survive. There are a
few types of bacteria that can survive in frozen water.
Atmosphere
 What is air?
 "Air" refers to an atmosphere, a collection of gases, which
can only exist around a semi-massive object in space.
 Is there “air” between earth and the moon?
 No because there is no atmosphere between the Earth and
moon.
Atmosphere
How does the
presence and
composition of an
atmosphere help
to determine a
planet’s surface
temperature?
Atmosphere
 The atmosphere is like a blanket
around the Earth -- and is made up of
78% nitrogen, 21% oxygen, 0.9%
argon, 0.03% carbon dioxide and
trace amounts of other gasses.
 The atmosphere does two main
things –
 It absorbs energy from the Sun
(traps heat).
 Recycles water and other
chemicals (water cycle).
Layers of the atmosphere
The
atmosphere
is thicker the
closer it is to
the Earth.
Atmosphere
Gravity
 The Atmosphere is held in place
due to gravity.
 The gravitational pull of an
object is due to the mass of the
object.
 Too little mass and you would
not have much of an atmosphere
(like the Moon or Mars)
 Too much mass and the air
pressure would squash a human
flat (like Jupiter or Saturn)
Magnetic Field
 A complex, invisible region that surrounds Earth. You could
think of it like a force field.
 The magnetic field protects us from Solar Winds and Storms.
 Solar Winds and Storms are highly energized particles ejected
from the sun.
 The magnetic field is formed by the motion of the molten iron
in the core of the Earth.
 The magnetic field allows us to use compasses and forms the
magnetic North and South Poles.
 http://www.youtube.com/watch?feature=player_embedded&v
=ujBi9Ba8hqs#! -- First 2 minutes
Magnetic Field
Mars
What do you think
the solar winds
are doing to the
planet Mars?
Magnetic Field
Earth
What do you think
the solar winds
are doing to the
planet Earth?
Water
Water is necessary for life as we know it. What evidence
is there that water may exist now or may have existed at
one time on other celestial bodies?
All of the water on or near the earth is called the
hydrosphere.
 This includes the oceans, rivers, lakes, and even the
moisture in the air.
 97 % of the earth's water is in the oceans.
 The remaining 3 % is fresh water; ¾ of the fresh
water is solid and exists in ice sheets/glaciers.
Water
Water on other Worlds
 Evidence for water on Mars:
 Mars has defined polar regions that contain water ice
 Mars rover Curiosity has identified a streambed
Water on other Worlds
 Evidence for water on Europa
(Jupiter’s 6th moon):
 Galileo Spacecraft inferred
through observation the
presence of a global salt water
ocean containing more water
than is present on Earth covered
in a thick, ice shell
 Tidal forces on Europa (gravity
interaction between Jupiter,
Europa and the other moons)
would be enough to keep the
interior of Europa liquid
HOLD ON!
 Gliese 581g?
 Astronomers say they have for the first time spotted a planet
beyond our own in what is sometimes called the Goldilocks
zone for life: Not too hot, not too cold. Juuuust right.
 Not too far from its star, not too close. So it could contain liquid
water. The planet itself is neither too big nor too small for the
proper surface, gravity and atmosphere. It's just right. Just like
Earth?
 We’ll see what future study of this finding brings us…
Exo-Planets