Download The Sun and the Origin of the Solar System

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Dialogue Concerning the Two Chief World Systems wikipedia, lookup

Ursa Minor wikipedia, lookup

Corvus (constellation) wikipedia, lookup

Nebular hypothesis wikipedia, lookup

Advanced Composition Explorer wikipedia, lookup

Astronomical unit wikipedia, lookup

Orrery wikipedia, lookup

Aquarius (constellation) wikipedia, lookup

Impact event wikipedia, lookup

Panspermia wikipedia, lookup

History of Solar System formation and evolution hypotheses wikipedia, lookup

Astronomical spectroscopy wikipedia, lookup

Tropical year wikipedia, lookup

IK Pegasi wikipedia, lookup

R136a1 wikipedia, lookup

Star formation wikipedia, lookup

Directed panspermia wikipedia, lookup

Astronomical naming conventions wikipedia, lookup

Comparative planetary science wikipedia, lookup

Standard solar model wikipedia, lookup

Comet wikipedia, lookup

Timeline of astronomy wikipedia, lookup

Oort cloud wikipedia, lookup

Formation and evolution of the Solar System wikipedia, lookup

Solar System wikipedia, lookup

Transcript
The Sun and the Origin
of the Solar System
•
•
•
•
Mid-sized, G-type main sequence star
Distance: 1 AU = 150 million km away
Size: Actual radius 700,000 km = 100 Earths
Temperature, Luminosity (surface) T = 6000 K
http://www.nasa.gov/multimedia/videogallery/i
ndex.html
• 99.86% of the total mass of the Solar System
• 75% hydrogen, 23% heliun
• 2% O, C, Ne, Fe
Sunspots
• surface areas that are darker than
surroundings (lower temperatures)
• regions of intense magnetic activity
Solar Evolution
Star (Sun) formation
Stellar Evolution
• The Sun is a middle-aged, low-mass, main-sequence
star
• 5 billion years ago:
– Beginning of its life on main-sequence
– Sun had 1/3 luminosity it has now.
• 5 billion years from now:
– End of its life on main-sequence
– Sun will have twice the luminosity it has now.
• When H is exhausted, core shrinks.
• Heats up
• High temperatures ignites a shell of H around
the core.
• Increased pressure drives the envelope of the
star outward.
• Creates a Red giant
– Contraction of core, raises the temperature
– Ignites He shell around the core
– Eventually the core stabilizes
– Envelope is ejected as a "planetary nebula"
– The core remains as a "white dwarf"
Solar system formation
•
Starting point:
– A cloud of interstellar gas and dust, the "solar
nebula“
– Most of it (98%) is hydrogen and helium, includes
dust grains of heavier material, formed in previous
generations of stars.
•
•
•
•
•
Contraction
Accretion disk
Protostar
Condensation
Planetesimals
http://www.youtube.com/watch?v=5l5mB-rFuGo
Asteroid Belt
• Small bodies in the inner solar system
• Asteroid Belt between Mars & Jupiter
• Orbits are strongly influenced by
Jupiter.
• Made of rock, metal, or a mix of the
two.
• >300,000 asteroidal objects
• >150,000 with good enough orbits to give
official numbers
• ~15,000 asteroids with official manes
• When you know its orbit, you can name it.
Examples of asteroid names
• Ceres (largest – 914 km)
• Eros (landed on in2001 Feb 12)
• Bach
• Beethoven
• Lennon
• McCartney
• Santana
• Clapton
Irregular shape
• Too small for gravity to make them spherical
Composition of Asteroids
• C-type: "Carbonaceous" – mostly carbonbearing materials. ~75% of all asteroids.
• S-type: "Silicaceous" - mostly of silicates
(stony or stony iron). 17% of all asteroids.
• M-type: "Metallic" - probably iron-rich
Asteroid Origins
• fragments of larger, differentiated bodies
shattered by collisions
• remnants of more primordial material that
never got differentiated
Impact with Earth
Would disrupt climates and trigger mass
extinctions
Meteoroids
• Chunks of rock & iron smaller
than asteroids orbiting the
Sun
• Sizes range from grains to
100 meters across
Meteor
• Streak of light when a
meteoroid enters the Earth's
atmosphere
• Most are tiny grains
• Meteor showers are trails of
debris left behind by passing
comets
Meteorite
• Any remnant that reaches the ground intact.
Russian Meteorite
• http://www.youtube.com/watch?v=90Omh7_I
8vI
Meteor Impacts
• About 100 tons of meteoroids hit the Earth
each day
• Most are no bigger than grains of sand or
smaller
Earth Impact Effects Program
http://impact.ese.ic.ac.uk/ImpactEffects/
Comets
Small bodies consisting of aggregates of ices
mixed with rock & dust
• As they approach the Sun, they heat up and
the ices sublimate (go from solid to gas):
Halley's Comet
• In 1705, Edmund Halley computed the orbit of
the great comet of 1682 using Newton's laws
• Found that orbit of 1682 comet was the same
as comets seen in 1531 & 1607.
• Predicted return in 1758.
• Seen again on Christmas day
1758, 12 years after
Halley's death
Origin of Comets
• Short-period comets are from the Kuiper Belt
• Long-period comets are from the Oort Cloud
Structure of Comets
• Nucleus:
– Dirty snowball of ices & dust
– >99% the mass of the comet
• Coma
– Bright "head" of the comet
– Low-density cloud of gas & dust sublimed off the
nucleus
– Extends out to 100,000 km or more
• Comets have two tails
– Dust Tail, dusty particles swept back in a curved
path by solar radiation, white
– Ion Tail, ionized atoms & molecules swept straight
back by the solar wind, blue
Comet Orbits
• Typically have a high degree of eccentricity
http://www.windows2universe.org/comets/com
et_model_interactive.html
Kuiper Belt
• Region of the Solar System beyond the planets
extending from the orbit of Neptune (at 30
AU) to approximately 55 AU from the Sun
Oort Cloud
• Cloud of comets which may lie roughly 50,000
AU, or nearly a light-year, from the Sun.
• Nearly a quarter of the distance to Proxima
Centauri, the nearest star to the Sun