Transcript Powers of ten notation

Rebirth of astrobiology
Discussion
Why would someone go all the way to
Antarctica just to collect meteorites?
Shergottite
Discussion
Though we have never returned a rock sample
from Mars, we are certain that these
meteorites came from there. How can we be
so sure?
Nakhlites
ALH 84001 history
1. Formed on Mars 4.091 billion years ago
2. Fractured by nearby impact 3.9-4.0 billion
years ago
3. Spent time under water
4. Launched into space 15 million years ago
5. Landed in Antarctica 13,000 years ago
6. Picked up in 1984
Carbonate globule
Polycyclic aromatic
hydrocarbons (PAH)
Formed by decay of dead organisms
Nanobacteria Controversy
1-2 nanometers in size
Self replicate in microbiological culture
Inculpated radio-labeled uridine
(component of RNA)
2008
self-propagating mineral-fetuin complexes
i.e. blood proteins.
Discussion
Is this enough evidence to convince you?
Problems
1. Most evidence can be reproduced abiotically
2. Contamination of meteorite
Unfairly rigorous level of proof?
“If all this had been seen in a terrestrial rock,
there wouldn’t be this level of skepticism.”
Simon J. Clemett
Lockheed Martin researcher
Mars Rover
Hematite deposit on Mars
Grey Hematite
Methane
Mars express detected small quantities of
methane in the Martian atmosphere
Discussion
Methane oxidizes very easily only lasting a
few years in Earth atmosphere. On Mars
methane can last only a few hundred years.
How does this gas get oxidized on Mars?
Discussion
Why is the discovery of methane on Mars
important?
Carbonate and Olivine deposits
Mars Science Laboratory
Mission
To assess whether Mars ever was, or is still
today, an environment able to support
microbial life, to determine the planet's
"habitability."
Curiosity landing site
Moons
Discussion
We can only see one side of the Moon from
Earth. Does this mean the Moon does not
rotate on an axis like the Earth does?
Newton’s Universal Law of
Gravity
• Every mass attracts every other mass
through a force called gravity
• The force is directly proportional to the
product of their masses
• The force is inversely proportional to the
square of the distance between them
Newton’s Universal Law of
Gravity
M 1M 2
F G
2
d
Discussion
The Earth’s gravitational force on the
Moon keeps the Moon in orbit around the
Earth. Does the Moon exert of force on
the Earth? Is this force greater than that
exerted by the Earth on the Moon, less
than, equal to, or is there no force?
Discussion
Which billiard ball experiences the greatest
force from the planet?
Discussion
How do the outer two balls appear to move
from the perspective of the center ball?
Explain.
Spring Tides and Neap Tides
The Sun also contributes to the Earth’s tides.
When the Sun and Moon line up to produce
higher tides, this is called spring tides.
Neap tides occur when the Moon and Sun
Partially cancel each other.
Tidal Friction
As the Earth rotates, it carries the tidal bulge
around with it, but the Moon, which orbits more
slowly than a day, tugs on this bulge and slows
the rotation of the Earth.
Thus the day is lengthening by about 0.002
seconds per century.
Tidal Friction
Discussion
Using the idea of tidal friction, explain why the
Moon orbits the Earth synchronously.
Synchronous rotation of the
Moon
Just as the Moon raises tides on the Earth, the
Earth raises tides on the Moon. But the tides
are not raised in water but in the very crust of
the Moon. The Earth’s gravity pulling on
these tidal bulges slowed the Moon’s rotation
period over millions to a period equal to that
of the Moon’s orbit.
Discussion
What are Kepler’s laws of planetary motion?
Discussion
In actuality, we can see 59% of the Moon’s
surface from the Earth. Explain why this is
the case using Kepler’s laws.
Conservation of angular
momentum
Any object that is spinning or orbiting has
angular momentum which is equal to the
mass × velocity × radius.
In the absence of an external torque, or
twisting force, the angular momentum
will remain constant.
The Earth-Moon system
The Moon exerts a force on the tidal
bulges on Earth, trying to twist the tidal
bugles back to face the Moon. This torque
slows the rotation of the Earth.
Discussion
If the Moon is slowing the Earth’s rotation
then the Earth is losing angular momentum.
But, if the angular momentum of the EarthMoon system has to be conserved, where
does that angular momentum go?
Orbit of the Moon
Due to conservation of angular momentum, the
slowing of Earth’s rotation requires the Moon to
move faster in its orbit. Because the force of
Earth’s gravity does not change, this means the
Moon is getting further away, by about 2 inches
per year.
Fate of the Earth Moon System
Over billions of years the length of the month
and the length of the day will be the same,
about 47 days. The Moon will then be
stationary in the sky.
Discussion
Will the Moon still have phases?
Pluto and Charon
Pluto has a large satellite named Charon
which orbits Pluto in 6.4 days. Like most
satellites in the solar system, Charon rotates
synchronously, keeping the same face
toward Pluto. In addition, like the future
Earth-Moon system, Pluto also rotates in 6.4
days, keeping the same face toward Charon.