Transcript Grade 9 Science Part 3 Other Celestial Bodies

Grade 9 Science Part 3
Other Celestial Bodies
http://www.sci2.com/#!/browse
http://www.sci2.com/#!/videos/37
http://suite3d.com/painting/planetarysuite.shtml
Key Terms
Planet
• Orbits a star
• Is not a star itself
• Spherical (requires sufficient mass/gravity)
• Dominates its orbit
Solar system
• Solar = sun (like a solar panel)
• System: involves many components
• A group of planets that orbit one or more stars
** Where does the solar system end?
Voyager 1 leaves the solar system!
• 722 kg spaceprobe launched on sept 5, 1977
• Purpose: to explore Jupiter and Saturn
• Moved on to explore the outer heliosphere
• Sept 12, 2013 crossed the heliopause
• farthest human-made object from the sun
• Now exploring the interstellar medium
• Expected to send signals until 2025
• http://voyager.jpl.nasa.gov/
http://voyager.jpl.nasa.gov/pdf/VoyagerPoster2010_Front.pdf
Layers
Outer planets
= gas giants
= Jupiter, Saturn,
Uranus, Neptune
Kuiper belt
IMAGE
Sun
Inner planets
Asteroid belt
= Terrestrial planets
= Mercury, Venus,
Earth, Mars
http://solarsystem.nasa.gov/planets/
Asteroids and the Asteroid Belt
- Small, non-spherical objects
- Left over debris from solar system formation
- Most are in the asteroid belt
- Size : sand to 500km across
- Can have moons (Example: Ida and its moon, Dactyl)
- Ceres (a dwarf planet) also is in the asteroid belt
- 65 million years ago an asteroid struck earth.
- Caused climate changes
- May have caused mass extinctions (dinosaurs!)
Asteroid Ida and its moon, Dactyl
Impact Events
• Haughton Crater in Nunavut:
• 23 km across. 39 million years ago
• Barriger Meteroite Crater in Arizona
• Equivalent to 1000 atomic bombs. 40-50000 years ag0.
• Tunguska Event 1908 in Siberia: destroyed 2000 km 2 (larger
than Kingston, ON)
• 120 ft across, 220-million pounds
• Heated to 44,500 F
• Explosion equal to 185 Hiroshima bombs
Redirecting asteroids
http://www.jpl.nasa.gov/news/news.php?release=2014-052
http://neo.jpl.nasa.gov/
Kuiper Belt
- Millions of small objects
- Fragments left over from the formation of the solar system
- Pluto is now considered part of this
Oort cloud
- Small icy fragments of debris
- 50000 AU – 100000 AU from Sun
- Spherical!
http://onlinephys.com/Kuiper-Belt-and-Oort-Cloud-of-the-Sun.jpg
Other Celestial Bodies
Comets
- Originate in Kuiper belt and Oort cloud
- Composed of dust, ice and rock
- Can move into the inner solar system by Jupiter’s
gravity
- when near the sun , forms two tails
- Gas tail (blue) ionized gases
- Particle tail (white) light reflects off of particles
- Periodic comets have stable orbits
Can be short period (<200 year orbit) or long period
Hale-Bopp (long period: 2380 years/orbit)
The coma points away from the sun pushed by solar winds
Comet collision
http://amazing-space.stsci.edu/news/archive/2005/02/photo-01.php
Meteoroids, Meteors, and Meteorites
• Meteoroids: chunks of rock moving through space
(broken from asteroids, comets or planets)
• Meteors: Meteroids burning up in the earth’s
atmosphere (shooting stars!)
• Shooting stars are NOT stars
• Meteor showers: when earth passes through trail of comet
debris
• Meteorites: Meteoroids that impact the earth’s
surface (~ 100 metric tonnes/year)
What is a light year?
The distance light travels in one Earth year.
1 light year = 9.46 x 10 12 km
ALL electromagnetic radiation (light)
travels at a constant speed:
Speed of light = 300 000 km/s
Galaxies
A collection of stars, gas, dust, and planets held
together by gravity.
• All stars are part of a galaxy
• Spiral and elliptical and irregular are the
primary types
William Herschel
• Discovered Uranus
• Coined the term asteroid
• Built and sold telescopes w/his sister
• First to discover galaxies beyond the Milky Way
The Milky Way Galaxy
• A hazy white band, which appears
brightest in summer
• Named by Greeks. Milk spilled by Hera
while feeding Hercules
• Everything you can see in the sky is part
of the milky way
• ~100 billion stars
http://en.wikipedia.org/wiki/File:Milk
y_Way_Night_Sky_Black_Rock_Dese
rt_Nevada.jpg
Local Group
If Andromeda was brighter,
this is what it would look
like in the sky!
• Milky way is part of
the LOCAL GROUP of
~40 galaxies
• Milky way and
Andromeda are the
largest in our local
group
Star clusters
• Collection of stars held together by gravity
• Open clusters (50-1000 stars) in milky way
arms
• Globular clusters (100000-1000000 stars)
• Spherical
• Superclusters: clusters of 4-25 clusters of galaxies
• Harlow Shapley noticed globular clusters only in
the direction of Hercules, Scorpius, Ophiuchus and
Sagittarius. Thus we must be far away in one of
the major arms
• Mapped the milky way with radio waves to
determine diameter and shape.
• 100000 light years in diameter
• Bulge at the center (looks like UFO from the side)
• Two major spiral arms and several minor
• Sun is 28000light years from the center
http://physics.highpoint.edu/~mdewitt/phy1050/?page=week6
Hubble
deep field
Video
https://www.youtube.com/watch?v=3tHY3XmlNSA
Homework
Read pgs. 313-317
Do questions on pg. 317
Read pg. 385-391
Do questions on pg. 391.