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									• no evidence for life beyond Earth – yet.
• multitude of good reasons to believe life is widespread.
• life may exist elsewhere in our solar system, not “intelligent life”
• the possibilities, i.e. number of places, where life may be are innumerable
• we are “star stuff” – God’s kitchen (the universe) builds all the ingredients for life
• thus, “ASTROBIOLOGY”, studying the development of life on Earth and in the universe!
5. Galaxy Cluster

                                     3. Galaxy (stellar system)

                4. Galaxy Group
                (several galaxies)

                                     2. Planetary System (with star)
1. Planet (ecosphere)
Distance measured in “light time”
speed of light = 300,000 km/s = 186,000 miles/sec
Sun-Earth distance…..........                8 light minutes
Solar System diameter…….                    22 light hours
Nearest Star…………………                          4 light years (lys)
Galaxy diameter………........             100,000 lys
Local Group diameter………              1,000,000 lys
Galaxy Cluster diameter…...        100,000,000 lys
Size of Universe…………….          12,000,000,000 lys
Anatomy of a Galaxy

250,000,000 yr rotation

20 Sun orbits
Solar System Formation
Gravity dominates – then angular momentum and pressure from heat.
Solar System Formation
Solar System Formation

• star born in center

• planets form in disk

• metal/rock “seeds” in inner disk

• ice “seeds” in outer disk

• gas survives in outer disk –
forms gas giants with ice cores

• star lights up – blows remaining
gas away

• Terrestrial Planets inner systems

• Jovian Planets outer system
                           The Solar System

         Relative Sizes…

           A Star a balance between gravity and pressure


Gravity tends to crush
the star, which causes                        The very center is called the
the temperature and the                       core. In the core the density
density to increase                           is ~150 times that of water
toward the center.                            and the temperature is 15
                                              million degrees Kelvin
Planetary Nebulae
 The Sun’s Fate     White Dwarf
                Supernovae Remnants in Our Galaxy

        Young                        Old

Fate of very Massive Stars…

                  Supernova in a
                  distant galaxy.
Atoms are comprised of a nucleus and electrons (in orbits -> would appear as a swarm or cloud)

    protons = positive charge; neutrons = no charge; electrons = negative charge
      The nucleus is extremely tiny; atoms are empty space!

                 = 4.5 football fields = 450 yards = 1350 feet = ¼ mile

This atom is blown up a trillion times = 1012 = 1,000,000,000,000
         Atoms are defined by atomic number = number of protons

                   hydrogen = 1; helium = 2; carbon = 6

        The number of electrons is equal to the number of protons.

A given atom does not always have the same number of neutrons (or mass).
These different “flavors” of a given atoms are called isotopes.
   How elements are built and energy is released

Fusion: small atoms bind together to form large atoms
Fission: break up large atoms to form small atoms

Shown is the energy released per fusion/fission event; this is
called the binding energy. Note that a large amount of energy
is released binding hydrogen into helium.

Still, it takes 1038 reactions per second to support the sun!
That is the conversion of 5 millions tons of mass into energy
every second. Thus mass is lost from the sun forever.

                              Note the special location of iron.
       The Energy Source of Life (and the chemical source!)

                e+                 Step 1 of the Proton-Proton Chain…

                                      1H   + 1H        2H   + e+ + n

Two hydrogen ions (1H) “collide”. They stick together, or fuse, into deuterium (2H), an
isotope of hydrogen- it has one proton and one neutron.

This is called fusion.

Also, in the process, a positron (e+, antimatter of electron) and a neutrino (n) are
produced. In the process the positron (anti-matter version of electron) finds a free
electron in the sun’s core plasma and when they collide they annihilate and release
energy (photons).
        The Energy Source of Life (and the chemical source!)

                              Step 2 of the Proton-Proton Chain…

                                        2H   + 1H       3He   +g

The deuterium from step 1 collides with a hydrogen, forming tritium, an isotope of
helium, with only one neutron instead of the typical two.

In the process, a photon (g) is produced. This photon carries away energy.
    The Energy Source of Life (and the chemical source!)

                       Step 3 of the Proton-Proton Chain…

                          3He   + 3He       4He   + 1H + 1H


                         Two tritium from two different step 2s collide and form
                         helium. In the process two hydrogen (1H) are
           e+            produced.
   Massive stars undergo multi-layered shell burning.

                                The time duration that each shell
                                burns becomes shorter and shorter
                                as the star becomes desperate to
                                battle against the merciless
                                crushing force of its own gravity.

Hydrogen .…… 7 million yrs           Oxygen ………. ½ yr
Helium …….…. 500 thousand yrs        Silicon ……….. 1 day
Carbon …….… 600 yrs                  Iron collapse … 0.1 second

Carbon, nitrogen, oxygen are
blasted into interstellar space!
                Interstellar Gas Clouds Have Chemistry

  Carbon is the most versatile chemical element (atom)

  It can make 1,2, 3, or 4 strong bonds

Compounds are molecules with more than one type of element…
These chemical elements form the next generation of planets!

          Which of these are good sites for biology?
On Earth, biology/life persists even in very hot and/or dark environments!

Black Smoker                                 Hot Spring
     On Earth, biology/life persists even in very cold/frozen environments!


Frozen rocks are the habitat of microbes.
They “hibernate” in a frozen state, and then
drink up when the sun warms the ice to
       Is Mars much different than Antarctica?
       Is the warm upper atmosphere of Jupiter teaming with microbes?

Mars is covered in a permafrost- are the
rocks any different than those in Antiarctica?
                                                 Room temperature about
                                                 300 km down
        Jupiter’s Moon Europa

                                             Covered with Water Ice-

                                             The cracks change with time,
                                             revealing a dynamic geology

                                             Dynamic geology means
                                             energy input into planet!

A theoretical cutaway of Europa – we think
the moon has a water ocean under the
surface ice…
         Saturn’s Moon Titan

                                        Thick Methane atmosphere…

                                        Laboratory experiments to create a
                                        “gas” to match the measured
                                        properties of Titan’s atmosphere
                                        suggest a hydrocarbon gas rich
                                        with organic molecules!

The Huygens Probe, supplied by the European Space Agency, has six
complex instruments aboard. The data from these instruments will be
received by the Cassini spacecraft and relayed to Earth after the probe
descends into Titan's mysterious atmosphere in early 2005.

astro – study of the universe
biology – study of life

astrobiology – study of life in the universe

NASA’s 3 main questions:

1. How does life begin and develop?

2. Does life exist elsewhere in the universe?

3. What is life’s future on Earth and beyond?

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