The origin of the Solar System

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The origin of the Solar System
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Small planets beyond Pluto Sedna, 1,300 1750
km dia.
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Our Solar System is about 16 billion km, or 10
billion miles, or 15 light hours across. Light
travels 300,000 km/sec or 1.1 billion km/hour
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Our galaxy, the Milky Way
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A galactic center More than 1 Million stars are
visible here!
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Edge-on view of a spiral galaxy. Our galaxy, the
Milky Way, would look very much like it to an
outside visitor
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Our galaxy, the Milky Way
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IRAS telescope image of ? Pictoris, a solar
system in the making? Red solid material.
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Star nurseries in the constellation Sagittarius
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The Big Picture

• The Big Bang, the birth of the Universe 13 Gy
  ago, produced H and He. These elements formed
  stars which cluster in galaxies with billions of
  stars our galaxy, the Milky Way, formed 10 Gy
  ago.
• Other elements are synthesized in the interiors
  of stars such as Red Giants and Supernovae.
• Upon ejection into interstellar space from dying
  stars, some elements condense into dust grains
  (presolar grains) and amorphous dust, either in
  stellar atmospheres or in interstellar space.
• Gas and dust collect into giant, cold molecular
  clouds.
• Dense cores collapse into stars, such as the Sun
  4.56 Gy ago and planets, asteroids and comets
  form.
• Asteroids collide and fragments fall on Earth as
  meteorites
• We study meteorites and the presolar grains which
  some of them contain. These tell us about the
  complex nucleosynthetic processes that are going
  on in stars, such as Supernovae, AGB stars, etc.

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The origin of the Solar System
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The critical role of Earths Moon in helping life
start and be sustained on Earth

• Moon adds stability to Earths rotation, so less
  extreme seasons
• Moon provides ocean tides on Earth promotes
  early life in shallow pools
• Moon slows Earths rate of rotation longer days

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Growth of continents with time
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Old parts of the Moon are very heavily cratered.
This indicates that early in the history of the
Solar System the Moon and, by inference, Earth
were very heavily bombarded by highly destructive
bullets from space (asteroids comets) Oldest
rocks on Earth are 3.85 Gy old. Older rocks were
destroyed by impacts and erosion There is
nothing left of the earliest period of Earth
history!
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The atomic bomb dropped on Hiroshima was 20 kt
(1 kt 1,000 t of TNT 1 mt 1,000 kt). Meteor
Crater Arizona 3 mt 150 Hiroshima bombs.
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How long does life exist on Earth
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Earth is unique Do not mess it up!
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Planets outside our Solar System, orbiting other
stars, in multiples of Jupiter masses (Mj).
Conclusion Most planets have masses equal to, or
a few times, the mass of Jupiter
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Planets outside our Solar System, orbiting other
stars, plotted as a function of the distance of
their star. Conclusion Most planets orbit
extremely closely to their stars!