Title: Chapter 4 The Solar System Interplanetary Matter and the Birth of Planets
1Chapter 4The Solar SystemInterplanetary Matter
and the Birth of Planets
- AST 1002 Introduction to Astronomy
- Dr. Mike Reynolds
2Our Solar System
- Made up of
- One Central Star
- Eight (or nine, or ten ) known Planets
- Satellites orbiting the Planets
- Miscellaneous debris Minor Bodies asteroids,
meteoroids, comets, dust - Astronomers believe the Solar System is about 4.6
billion years old - Why do we think it is that old?
- Through the study of meteorites and dating of
these objects
3Solar System Formation
- Sohow did the Solar System form and end up with
all these different types of objects? - Currently the best theory is the Nebular Theory
- The Solar System developed out of an interstellar
cloud of dust and gas - Cloud of dust and gas also called a Nebula
- This theory best accounts for the objects we
currently find in the Solar System and the
distribution of these objects -
4Nebular Theory Specifics
- Started with a cloud of gas and dust
- Most likely left over from a previous supernovae
- Nebula started to collapse and condense this
process continued - The Sun-to-be collected most of the mass in the
nebulas center, forming a Protostar - Protostar No nuclear fusion at first
- Probably next flattened into a disk called the
Protoplanetary Disk - Planets eventually formed from / in this disk
5Why is the Solar System Orderly?
- With a beginning as a cloud of gas and dust, this
cloud most likely was - Somewhat spherical
- Had a low pressure and low density
- Something started the nebula collapse
- Once the collapse began, gravity would have
caused the collapse to continue
6Processes and Results
- Three processes occurred with the nebular
collapse - Temperatures continued to increase
- The solar nebula spun faster and faster
- The solar nebula disk flattened
- The orderly motions of the Solar System today are
a direct result of the Solar Systems beginnings
in a spinning, flattened cloud of gas and dust
7What Evidence Do We Have?
- We see discs of gas and dust around other stars
- Evidence of stars forming in clouds of gas and
dust - Computer modeling
- Other disk-forming evidence found throughout the
Universe - Similar Situations and modeling, like spiral
galaxies
8Other Important Evidence
- The types of objects found within the Solar
System provide significant clues - Types of Planets and their distributions
- Rocky or Terrestrial close to the Sun
- Gas Giants or Jovian far from the Sun
- Dwarf Icy far , far from the Sun
- Comets and Asteroids
- Meteorites recovered on Earth
- Motions of most Solar System objects
- Orbit and rotate in an organized fashion
9But Alas! A Few Exceptions
- Pluto,
- Eris
- Earth with a large moon
- Uranus tilted on its side
- Venus retrograde rotation
10Other Solar Systems?
- Yes! We have found evidence of Extra-Solar
Planets - Look for a wiggle in the stars position via its
spectrum (red/blue shifts) - Finds the planet indirectly
- Dr. Geoff Marcy first to see this
- Also look for a brightness drop transit
- Gravitational lensing
- BIG! Most of these are much bigger than Jupiter
- Three planets have been found around the star
Upsilon Andromeda - Over 160 Stellar Systems have been discovered to
date!
11Data courtesy Chabot Observatory Dr. Terry
Galloway et al.
12A couple of Earth-Size Planets
- HD 69830
- Announced in January 2006
- Appears to be five Earth Masses, Icy planet (more
like Pluto/Eris than Earth) - Discovered by gravitational lensing
- Artist's impression
- Credit European
- Space Organization
-
13The 1st Really Earth-Like Extrasolar Planet
Discovered
Gliese 581c
14What is Gliese 581?
- A red dwarf star
- Mass is 1/3 that of the Sun
- Red dwarfs are at least 50 times fainter than the
Sun and are the most common stars in our Galaxy - Located 20.40 light years from Earth
- Among the 100 closest stars to us
15The Gliese 581 System
- Currently known to have three planets
- Gliese 581b 16X as massive as Earth completes
one orbit of Gliese 581 in 5.4 days - Appears to be Neptune-like
- Gliese 581c rocky planet 1.5X Earths radius
- Gliese 581d 8X as massive as Earth orbits
Gliese 581 in 84 days
16What About Gliese 581c
- Gliese 581c is 14X closer to its star than the
Earth is from the Sun - It is estimated that the mean temperature of
Gliese 581c lies between 0o and 40o C - water would thus be liquid.
- Its radius should be only 1.5 times the Earth's
radius, and models predict that the planet should
be either rocky - like our Earth - or covered
with oceans. - Stéphane Udry
- Member of the discovery team
17Artists impression of Gliese 581 system Credit
ESO
18What is Gliese 581c? A planet of Jabba the Hutts?
Well you would have to adjust Jabba for the 2X
Earth's gravity!
19Liquid water is critical to life as we know it.
Because of its temperature and relative
proximity, this planet will most probably be a
very important target of the future space
missions dedicated to the search for
extra-terrestrial life. On the treasure map of
the Universe, one would be tempted to mark this
planet with an X.
- Xavier Delfosse
- Member of the discovery team from Grenoble
University (France)
20HD 69830 Gliese 581cA Comparison
21Extrasolar Planets
- Can tell us a lot about our Solar System
formation - There are some significant issues at this point
- Extrasolar planets are mostly much bigger than
Jupiter - Extrasolar planets orbit much closer to their
stars than our Gas Giants - Theory here is these Gas Giants migrated closer
to their stars
22(No Transcript)