Grade 9 Science Part 3Other Celestial Bodies

http://www.sci2.com/#!/videos/37

http://www.sci2.com/#!/browse

http://suite3d.com/painting/planetarysuite.shtml

1. Geocentric Model • Geo = earth, Centr= centre• Ptolemy during 2nd century AD (C.E)• Lasted 1500 years• Earth is the center of the solar system

(instead of the sun)

Models of the Solar System

2. Heliocentric model• Helio = sun, centr= centre• Nicolaus Copernicus (early 1500’s)• Orbits with perfect circles

3. Johannes Kepler (1571-1630) demonstrated elliptical orbits• Current model = heliocentric with elliptical

orbits

http://hendrianusthe.wordpress.com/2012/06/21/heliocentric-vs-geocentric/

Key TermsPlanet

• 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?

• 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/

Voyager 1 leaves the solar system!

http://voyager.jpl.nasa.gov/pdf/VoyagerPoster2010_Front.pdf

http://solarsystem.nasa.gov/planets/

IMAGE

Sun Inner planets = Terrestrial planets= Mercury, Venus, Earth, Mars

Asteroid belt

Outer planets = gas giants = Jupiter, Saturn, Uranus, Neptune

Kuiper belt

Layers

- 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!)

Asteroids and the Asteroid Belt

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 km2 (larger than Kingston, ON)• 120 ft across, 220-million pounds• Heated to 44,500 F• Explosion equal to 185 Hiroshima bombs

http://www.jpl.nasa.gov/news/news.php?release=2014-052

http://neo.jpl.nasa.gov/

Redirecting asteroids

- Millions of small objects

- Fragments left over from the formation of the solar system

- Pluto is now considered part of this

Kuiper Belt

- Small icy fragments of debris

- 50000 AU – 100000 AU from Sun

- Spherical!

Oort cloud

http://onlinephys.com/Kuiper-Belt-and-Oort-Cloud-of-the-Sun.jpg

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

Other Celestial Bodies

Hale-Bopp (long period: 2380 years/orbit)

The coma points away from the sun pushed by solar winds

http://amazing-space.stsci.edu/news/archive/2005/02/photo-01.php

Comet collision

• 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)

Meteoroids, Meteors, and Meteorites

The distance light travels in one Earth year.

1 light year = 9.46 x 1012 km

ALL electromagnetic radiation (light) travels at a constant speed:

Speed of light = 300 000 km/s

What is a light year?

GalaxiesA 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

• 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

The Milky Way Galaxy

http://en.wikipedia.org/wiki/File:Milky_Way_Night_Sky_Black_Rock_Desert_Nevada.jpg

Local Group

• Milky way is part of the LOCAL GROUP of ~40 galaxies

• Milky way and Andromeda are the largest in our local group

If Andromeda was brighter, this is what it would look like in the sky!

• 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

Star clusters

• 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

https://www.youtube.com/watch?v=3tHY3XmlNSA

Video

Read pgs. 313-317

Do questions on pg. 317

Read pg. 385-391

Do questions on pg. 391.

Homework