Meteor Strike

Watch Meteor Strike on PBS. See more from NOVA.

Chris McGown's Midterm

Amber Reed's Notes

10.1 A closer look at the sun

Why does the sun shine?

Chemical energy content~10,000 years
Luminosity 

Gravitational potently energy~25 billion years 
Luminosity 

Nuclear potential energy (core)~ 10 billion years 
Luminosity  

-Weight of upper layers compress lower layers
-Gravitational equilibrium : gravity pulling in balances pressure pushing out
-energy balance : thermal energy released by fusion in core balances radiative energy lost from surface 
-gravitational contraction provided energy that heated the core of the sun 

What is the structure of the sun??

-Solar wind: flow of charged particles
-Corona: outermost layer of solar atmosphere~1million K
-Chromosphere: middle layer if solar atmosphere ~10^4-10^5 K
-Photosphere: visible surface of the sun ~6000 K
-Convection zone: energy transported upward by rising hot gas
-Radiation zone: energy transported upward by photons
-Core: energy generated by nuclear fusion ~15 million K

10.2 nuclear fusion in the sun 

How does nuclear fusion occur in the sun?

-Fission: big nucleus splits into smaller pieces ( nuclear power plants)
-Fusion: small nuclei stick together to make a bigger one ( sun and stars)
-High temps enable nuclear fusion to happen in the core 
-The sun releases energy by fusing four hydrogen nuclei into one helium nucleus 
Proton-proton chain is how hydrogen fuses into helium in the sun
In=4 protons
Out=He nucleus, 2 gamma rays , 2 positrons , 2 neutrinos
Mass is lower than .7%

Solar thermostat :
Decline in core temp causes fusion rate to drop, so core contracts and heats up
Rise in core temp causes fusion rate to rise, so core expands and cools down 

How does the energy form fusion get out of the sun?
-Energy gradually leaks out of the radiation zone in the form of randomly  bouncing photons 
-convection (rising hot gas) energy to the surface 

How do we know what is happening inside the sun?

-Making mathematical models
-Observing solar vibrations
-Observing solar neutrinos 

-Patterns of vibration on the surface tell us abut what the sun is like inside 
-data on solar vibrations agree with mathematical models of solar interior
-neutrinos created during fusion fly directly through the sun
-observations of these solar neutrinos can tell us whats happening in the core

Solar neutrino problem :
- early searches for solar  neutrinos failed to find the predicted number 
-More recent observations find the right number of neutrinos but some have changed  

10.3 the sun-earth connection

What causes solar activity?
-solar activity is like "weather" on earth
-sunspots : are cooler than other parts of the sun's surface (4000K). Are regions with strong magnetic fields
-solar flares:
-solar prominences
( all these phenomena are related to magnetic fields )

-Zeeman effect: we can measure magnetic fields in sunspots by observing the splitting of spectral lines 
-Loops of bright gas often connect sunspot pairs
-Magnetic activity also causes solar prominences that erupt high above the sun's surface 
-The corona appears bright in x-ray photos in places where magnetic fields trap hot gas

Coronal mass ejections: send bursts of energetic charged particles out to the solar system 
-charged particles streaming from the sun can distrust electrical power grids and disable communications satellites 

How does solar activity vary with time?

-The number is sunspots rises and falls in 11 year cycles
-the sunspot cycle has something to do with the winding and twisting of the sun's magnetic field 


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We start today the study of stars.

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Amber Reed Quiz

Why is there an asteroid belt? 

Orbital resonances are asteroids in orbital resonance with Jupiter experience periodic nudges. Eventually those nudges move asteroids out of resonant orbits leaving gaps in the belt .

How are meteorites related to asteroids? 
Most meteorites are pieces of asteroids. Meteorites is a air k from Alsace that falls through earths atmosphere. Meteor is the bright trail left by meteorite.

How do comets get their tails? 

Formed beyond the frost line, comets are icy counterparts to asteroids.  Also the nucleus of a comet is Ike a " dirty snowball". Most comets do not have tails. Comets remain perpetually for sun in outer solar system. Only comets that enter in inner solar system grow tails .


How big can a comet be?
Pluto's orbit is tilted and significantly elliptical. Neptune orbits three times during the time Pluto  orbits twice.


What are Pluto and other large objects of the Kuiper belt like? 
It's largest moon, Charon us nearly as large as Pluto itself .Pluto is very cold (40k)and also has a thin nitrogen atmosphere that refreezes onto the surface as pluto's orbit takes it farther from the sun.


Have we ever witnessed a major impact?
Comet SL9 caused a string of violent impacts on Jupiter in 1994 reminding us that catastrophic collisions still happen. Also tidal forces tore it apart during a previous encounter with Jupiter.

Did an impact kill the dinosaurs?
Fossil record shows occasional large dips in the diversity of species:mass extinctions. The most recent was 65million years ago, ending the reign of the dinosaurs. Iridium  is very rare in earth surface rocks but is often found in meteorites. Luis and Walter Alvarez found a worldwide layer containing iridium laid down 65 million years ago probably by a meteorite impact. Dinosaur fossils all lie below this layer.

Is the impact threat a real danger or just media hype? 
Asteroids and comets have hit Earth.  Some major impact is only a matter of time:not IF but WHEN.  Yet major impacts are very rare. Extinction level events~millions of years.  Major damage ~tens to hundreds of years.

How do other planets affect impact rates and life on Earth? 
The Influence of Jovian planets are the gravity of a Jovian planet (especially Jupiter) can redirect a comet . Jupiter has directed some comets towards Earth but has ejected many more into the Oort Cloud. 

Amber Reed

Midterm Jessica Brandon

Midterm

1.Have we ever witnessed a major impact?

a) The most recent major impact happened in 1994, when fragments of comet SL9 hit Jupiter

2. Why are Jupiter's Galilean moons geologically active?

b) Tidal heating drives activity, leading to Io's volcanoes and ice geology

3. What geological processes shape Earth's surface?

c) Impact cratering, volcanism, tectonics, and erosion

4. What theory best explains the features of our solar system?

d) The nebular theory, which holds that our solar system formed from a cloud of interstellar gas, explains the general features of our solar system 

 5. Where did asteroids and comets come from?

a) They are leftover planetesimals, according to the nebular theory

 6. What is matter?

b) Ordinary matter is made of atoms, which are made of protons, neutrons, and electrons

 7. What are the three basic types of spectra?

c) Continuous spectrum, emission line spectrum, and absorption line spectrum

  8. What keeps a planet rotating and orbiting the Sun?

d) Conservation of angular momentum

9. Write down Newton's formula for the force of gravity.

A 

10.  How did astronomical observations benefit ancient societies?

b) Keeping track of time and seasons; navigation

Midterm: Olivia Ward

1. Have we ever witnessed a major impact?

a) The most recent major impact happened in 1994, when fragments of comet SL9 hit Jupiter

b) No

c) Sixty five millions years ago a meteorite killed the dinosaurs

d) A huge impact caused the Moon to form

    2. Why are Jupiter's Galilean moons geologically active?

a) They have continental drift

b) Tidal heating drives activity, leading to Io's volcanoes and ice geology on other moons

c) The cores of these moons are highly radioactive

d) Meteorites produce volcanoes

  3. What geological processes shape Earth's surface?

a) Only water flow

b) Only the wind

c) Impact cratering, volcanism, tectonics, and erosion

d) Only impacts

 4. What theory best explains the features of our solar system?

a) The evolution theory of Charles Darwin

b) The Bohr model

c) The nebular theory, which holds that our solar system formed from a cloud of planets, and a star

d) The nebular theory, which holds that our solar system formed from a cloud of interstellar gas, explains the general features of our solar system 

 5. Where did asteroids and comets come from?

a) They are leftover planetesimals, according to the nebular theory

b) They are extinct planets

c) They are extinct stars

d) They are remnants of a Black Hole

 6. What is matter?

a) Made mainly of neutrinos 

b) Ordinary matter is made of atoms, which are made of protons, neutrons, and electrons

c) Made of tachyons

d) Made of axions 

 7. What are the three basic types of spectra?

a) Convection, conduction, and radiation

b) Red, green, and blue

c) Continuous spectrum, emission line spectrum, and absorption line spectrum

d) Hydrogen, Helium, and Lithium

  8. What keeps a planet rotating and orbiting the Sun?

a) The mass of the Sun

b) The mass of the planet

c) The law of inertia

d) Conservation of angular momentum

  9. Write down Newton's formula for the force of gravity.

a)

b)                                                                 

c)                                                               

d)                                                               

  10.  How did astronomical observations benefit ancient societies?

a) Allow them to predict war winners

b) Keeping track of time and seasons; navigation

c) Allow them to know the future names of kings

d) That way they knew the numbers of the winning lottery tickets

Chapter 9 Quiz: Olivia Ward

1. Why is there an asteroid belt?
   
   There is an asteroid belt due to orbital resonance. Orbital resonance with Jupiter disrupted the orbits of planetesimals, located in the asteroid belt, which prevented them from forming into a terrestrial planet. Many planetesimals were ejected, but some remained. These make up the asteroid belt today. Most of the asteroids, which were located in other areas of the inner solar system, have crashed into one of the planets.
   
2. How are meteorites related to asteroids?
   
   Most meteorites are pieces of asteroids. Primitive meteorites have no experienced changes since the birth of the solar system. Processed meteorites are fragments of larger asteroids that have gone through differentiation.
   
3. How do comets get their tails?
   Comets get their tails from sublimation. Comets are the icy leftovers of planet formation. If a comet comes near the Sun, the nucleus heats up and its ice undergoes sublimation. The escaping gases carry along with dust. This forms a coma and two tails: a plasma tail of ionized gas, and a dust tail.
   
4. Where do comets come from?
   
   Comets come from either the Kuiper Belt or the Oort Cloud. The Kuiper Belt comets are still located in a region beyond Neptune, where they formed. The Oort Cloud comets formed between the jovian planets and were kicked out by gravitational encounters with these planets.
   
5. How big can a comet be?
   
   Icy planetesimals in the Kuiper Belt were able to grow up to thousands of km in size. Eris is the largest known of these objects. Pluto is the second largest.
   
   
6. What are Pluto and other large objects of the Kuiper belt like?
   
   Pluto and other large objects of the Kuiper Belt are ice-rich. They orbit the Sun between the orbit of Neptune and twice that distance from the Sun. Their orbits tend to be elliptical and more inclined than those of terrestrial and jovian planets.
   
7. Have we ever witnessed a major impact?
   
   In 1994, fragmented Comet Shoemaker-Levy 9 impacted Jupiter which scarred its atmosphere for months. In 2009, there was another impact on Jupiter.
   
   
8. Did an impact kill the dinosaurs?
   
   A major impact may not have been the only cause for extinction of dinosaurs, but mass extinction coincides with the major impact. This occurred 65 million years ago. Sediments from this time contain Iridium. An impact crater of the same age is located along the coast of Mexico.
   
9. Is the impact threat a real danger or just media hype?
   
   Impacts are a threat, but the probability of a major impact happening in our lifetimes is low. It's not a matter of if a major impact will happen, it's a matter of when. Major impacts may occur every few hundred years.
   
10. How do other planets affect impact rates and life on Earth?
    
    Impacts are always linked to the gravitational influence of Jupiter and other jovian planets. These influences have shaped the asteroid belt, the Kuiper belt, and the Oort Cloud. The influences also continue to determine when objects are flung in our direction.

Chapter 9 Notes: Olivia Ward

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

9.1 Asteroids and Meteorites
Why is there an asteroid belt?

• Discovering Asteroids
  
  • Asteroids leave trails in long-exposure images because of their orbital motion around the Sun.
• Asteroid Facts
  
  • Rocky leftovers of planet formation
  • The largest is Ceres (diameter of about 1000 km).
  • There are 150,000 listed in catalogs and probably over a million with diameters > 1 km.
  • Small asteroids are more common than large asteroids.
  • All the asteroids in the solar system wouldn't add up to the size of a small terrestrial planet.
  • Asteroids are cratered and not round.
• Asteroids with Moons
  • Some large asteroids have their own moons.
  • Asteroid Ida has a moon named Dactyl.
• Asteroid Orbits
  
  • Most asteroids orbit in a belt between Mars and Jupiter.
  • They are not the debris of previous planets.
  • Trojan asteroids follow Jupiter's orbit.
  • Orbits of near-Earth asteroids cross Earth's orbit.
  • The belt is where all the asteroids happened to survive (resonance).
• Orbit Resonance
  
  • Asteroids in orbital resonance with Jupiter experience periodic nudges.
  • Eventually those nudges move asteroids out of resonant orbits, leaving gaps in the belt.
• Origin of Asteroid Belt
  
  • Rocky planetesimals between Mars and Jupiter did not form into a planet.
  • Jupiter's gravity through influence of orbital resonances, stirred up asteroid orbits and prevented their accretion into a planet.

How are meteorites related to asteroids?

•  Origin of Meteorites
  
  • Most meteorites are pieces of asteroids.
• Meteor Terminology
  
  • Meteorite: A rock from space that falls through Earth's atmosphere.
  • Meteor: The bright tail left by a meteorite.
• Meteor Types
  
  • Primitive: Unchanged in composition since they first formed 4.6 billion years ago. 
  • Strong Primitive Meteorite: Made of rocky material embedded with shiny metal flakes.
  • Carbon-rich Primitive Meteorite: Also rock with dark carbon compounds and small whitish spheres.
  • Processed: Younger, have experienced processes such as volcanism or differentiation.
  • Metal-rich Processed Meteorite: Made of iron and other metals that came from a shattered asteroid's core.
  • Rocky Processed Meteorite: Resembles volcanic rocks found on Earth.
• Meteorites from the Moon and Mars
  
  • A few meteorites arrive on Earth from the Moon and Mars.
  • Composition differs from the asteroid fragments.
  • This is a cheap (but slow) way to acquire Moon rocks and Mars rocks.

9.2 Comets
Was there every geological activity on the Moon or Mercury?

• Comet Facts
  • Formed beyond the frost line, comets are icy counter parts to asteroids.
  • The nucleus of a comet is like a "dirty snowball."
  • Most comets do not have tails.
  • Most comets remain perpetually frozen in the outer solar system.
  • Only comets that enter the inner solar system grow tails (cold to hot causes tails).
• Nucleus of a Comet
  
  • A "dirty snowball"
  • Source of material for comet's trail (dust tail, plasma tail)
• Anatomy of a Comet
  
  • Coma is atmosphere that comes from heated nucleus.
  • Plasma tails: gas escaping from coma, pushed by solar winds.
  • Dust tails are pushed by protons.
• Deep Impact
  
  • Mission to study nucleus of Comet Tempel 1
  • Projectile hit surface on 4 July 2005
  • Many telescopes studied the aftermath of impact
  • Comets eject small particles that follow the comet around in its orbit and cause meteor showers when Earth crosses the comet's orbit.

Where do comets come from?

• Only a tiny number of comets enter the inner solar system: most stay far from the Sun.
  
  • Oort Cloud: comets on random orbits extending to about 50,000 AU
  • Kuiper Belt: Comets on orderly orbits at 30-100 AU in disk of solar system
• How did they get there?
  • Kuiper Belt comets formed in the Kuiper Belt.
    
    • Flat plane aligned with the plane of planetary orbits
    • Orbiting in the same direction as planets.
  • Oort Cloud comets were once closer to the Sun, but they were kicked father out by gravitational interactions with Jovian planets.
    
    • Spherical distribution
    • Orbiting in any direction

9.3 Pluto: Lone Dog No More
How big can a comet be?

• Pluto's Orbit
  
  • Pluto's orbit is tilted and significantly elliptical.
  • Neptune orbits 3 times during the time Pluto orbits twice - resonance prevents a collision.
• Is Pluto a Planet?
  • Much smaller than the 8 major planets
  • Not a gas giant like the outer planets
  • Has very elliptical inclined orbit
  • Pluto has more in common with comets than the 8 major planets.
  • 2006: Pluto was named a dwarf planet.
• Discovering Large Ice Balls
  • Summer 2006: Astronomers discovered Eris, an ice ball larger than Pluto.
    
    • Eris has a moon: Dysnomia
• Other Icy Bodies
  
  • There are many icy objects like Pluto on elliptical, included orbits beyond Neptune.
  • The largest ones are comparable in size to Earth's moon.
• Kupier Belt Objects
  
  • These large, icy objects have orbits similar to the smaller objects in the Kuiper Belt that become short period comets.

What are Pluto and other large objects of the Kuiper Belt like?

• What is Pluto like?
  
  • Its largest moon, Charon, is nearly as large as Pluto itself.
  • Pluto is very cold (40 degrees K).
  • Pluto has a thin nitrogen atmosphere that refreezes onto the surface as Pluto's orbit takes it farther from the Sun.
• Other Kuiper Belt Objects
  
  • Most have been discovered very recently and little is known about them.
  • NASA's New Horizons mission will study Pluto and a few other Kuiper Belt objects.

9.4 Cosmic Collision: Small Bodies Vs. The Planets
Have we ever witnessed major impact?

• Comet SL9 caused a strong of violent impacts on Jupiter in 1994, reminding us that catastrophic collisions still happen.
  • Tidal forces tore it apart during a previous encounter with Jupiter.

Did an impact kill the dinosaurs?

• Mass Extinctions
  
  • Fossil records show occasional large dips in the diversity of species: mass extinction
  • The most recent was 65 million years ago, ending the reign of the dinosaurs.
• Iridium: Evidence of an Impact
  
  • Iridium is very rare in Earth's surface rocks but is often found in meteorites.
  • Luis and Walter Alvarez found a worldwide layer containing Iridium, laid down 65 million years ago, probably by a meteorite impact.
  • Dinosaur fossils are all below this layer.
• Iridium Layer
  
  • No dinosaur fossils in upper rock layers
  • Thin layer containing the rare element Iridium
  • Dinosaur fossils in lower rock layer
• Consequences of an Impact
  
  • A meteorite 10 km in size would send large amounts of debris into the atmosphere.
  • Debris would reduce the amount of sunlight reaching Earth's surface.
• Likely Impact Site
  
  • Geologists found a large subsurface crater about 65 million years old in Mexico.
  • Size of crater suggests impacting object was about 10 km in diameter.
  • Impact of such a large object would have ejected debris high into Earth's atmosphere.

Is the impact threat a real danger or just media hype?

• Facts About Impacts
  
  • Asteroids and comets have hit Earth.
  • A major impact is only a matter of time. It's not 'If', but 'When'
  • Major impacts are very rare.
  • Extinction level events can be expected in millions of years.
  • Major damage can be expected in tens of hundreds of years.
• Frequency of Impacts
  
  • Small impacts happen almost daily.
  • Impacts large enough to cause mass extinction are many million years apart.
• The Asteroid With Our Name on It
  
  • We haven't seen it yet.
  • Deflection is more probable with years of advanced warning.
  • Control is critical: Breaking a big asteroid into a bunch of little asteroids is likely to help.
  • We get less advanced warning of a killer comet.

How do other planets affect impact rates?

• Influence of Jovian Planets
  
  • The gravity of a jovian planet (especially Jupiter) can redirect a comet.
  • Jupiter has directed some comets.

Allison Thompson Midterm

1. Have we ever witnessed a major impact?
1. A) The most recent major impact happened in 1994, when fragments of comet SL9 hit Jupiter
2.  Why are Jupiter's Galilean moons geologically active?
1.  B) Tidal heating drives activity, leading to Io's volcanoes and ice geology on other moons
3.  What geological processes shape Earth's surface? 
1.  C) Impact cratering, volcanism, tectonics, and erosion
4.  What theory best explains the features of our solar system?
1. D) The nebular theory, which holds that our solar system formed from a cloud of interstellar gas, explains the general features of our solar system
5.  Where did asteroids and comets come from?
1.  A) They are leftover planetesimals, according to the nebular theory 
6.  What is matter?
1.  B) Ordinary matter is made of atoms, which are made of protons, neutrons, and electrons
7. What are the three basic types of spectra?
1.  C) Continuous spectrum, emission line spectrum, and absorption line spectrum
8.  What keeps a planet rotating and orbiting the Sun?
1.  a) The mass of the Sun
9.  Write down Newton's formula for the force of gravity.
1.  

 10.How did astronomical observations benefit ancient societies?
                1.  B) Keeping track of time and seasons; navigation

Jessica Horn's Midterm

1. Have we ever witnessed a major impact?

a) The most recent major impact happened in 1994, when fragments of comet SL9 hit Jupiter

b) No

c) Sixty five millions years ago a meteorite killed the dinosaurs

d) A huge impact caused the Moon to form

    2. Why are Jupiter's Galilean moons geologically active?

a) They have continental drift

b) Tidal heating drives activity, leading to Io's volcanoes and ice geology on other moons

c) The cores of these moons are highly radioactive

d) Meteorites produce volcanoes

  3. What geological processes shape Earth's surface?

a) Only water flow

b) Only the wind

c) Impact cratering, volcanism, tectonics, and erosion

d) Only impacts

 4. What theory best explains the features of our solar system?

a) The evolution theory of Charles Darwin

b) The Bohr model

c) The nebular theory, which holds that our solar system formed from a cloud of planets, and a star

d) The nebular theory, which holds that our solar system formed from a cloud of interstellar gas, explains the general features of our solar system 

 5. Where did asteroids and comets come from?

a) They are leftover planetesimals, according to the nebular theory

b) They are extinct planets

c) They are extinct stars

d) They are remnants of a Black Hole

 6. What is matter?

a) Made mainly of neutrinos 

b) Ordinary matter is made of atoms, which are made of protons, neutrons, and electrons

c) Made of tachyons

d) Made of axions 

 7. What are the three basic types of spectra?

a) Convection, conduction, and radiation

b) Red, green, and blue

c) Continuous spectrum, emission line spectrum, and absorption line spectrum

d) Hydrogen, Helium, and Lithium

  8. What keeps a planet rotating and orbiting the Sun?

a) The mass of the Sun

b) The mass of the planet

c) The law of inertia

d) Conservation of angular momentum

  9. Write down Newton's formula for the force of gravity.

a)

b)                                                                 

c)                                                               

d)                                                               

  10.  How did astronomical observations benefit ancient societies?

a) Allow them to predict war winners

b) Keeping track of time and seasons; navigation

c) Allow them to know the future names of kings

d) That way they knew the numbers of the winning lottery tickets 

Michael Redmond Quiz

1. Why is there an asteroid belt? -Rocky planetismals survived in the asteroid belt between Mars and Jupiter because they did not accrete into a planet.
2. How are meteorites related to asteroids? they are asteroids that fall through earth's atmosphere.
3. How do comets get their tails? ice on it evaporated from the sun.
4. Where do comets come from? outside the frost line in the Oort Cloud or Kuiper Belt.
5. How big can a comet be? Eris was discovered to be slightly bigger than pluto.
6. What are Pluto and other large objects of the Kuiper belt like? they orbit in the same direction as planets and are icy.
7. Have we ever witnessed a major impact? yes on jupiter Comet SL9.
8. Did an impact kill the dinosaurs? Yes. 
9. Is the impact threat a real danger or just media hype? It is a real danger that can happen every 100 million years or so.
10. How do other planets affect impact rates and life on Earth? the gravity of jovian planets could redirect a comet.

Midterm

1. Have we ever witnessed a major impact?

a) The most recent major impact happened in 1994, when fragments of comet SL9 hit Jupiter

b) No

c) Sixty five millions years ago a meteorite killed the dinosaurs

d) A huge impact caused the Moon to form

    2. Why are Jupiter's Galilean moons geologically active?

a) They have continental drift

b) Tidal heating drives activity, leading to Io's volcanoes and ice geology on other moons

c) The cores of these moons are highly radioactive

d) Meteorites produce volcanoes

  3. What geological processes shape Earth's surface?

a) Only water flow

b) Only the wind

c) Impact cratering, volcanism, tectonics, and erosion

d) Only impacts

 4. What theory best explains the features of our solar system?

a) The evolution theory of Charles Darwin

b) The Bohr model

c) The nebular theory, which holds that our solar system formed from a cloud of planets, and a star

d) The nebular theory, which holds that our solar system formed from a cloud of interstellar gas, explains the general features of our solar system 

 5. Where did asteroids and comets come from?

a) They are leftover planetesimals, according to the nebular theory

b) They are extinct planets

c) They are extinct stars

d) They are remnants of a Black Hole

 6. What is matter?

a) Made mainly of neutrinos 

b) Ordinary matter is made of atoms, which are made of protons, neutrons, and electrons

c) Made of tachyons

d) Made of axions 

 7. What are the three basic types of spectra?

a) Convection, conduction, and radiation

b) Red, green, and blue

c) Continuous spectrum, emission line spectrum, and absorption line spectrum

d) Hydrogen, Helium, and Lithium

  8. What keeps a planet rotating and orbiting the Sun?

a) The mass of the Sun

b) The mass of the planet

c) The law of inertia

d) Conservation of angular momentum

  9. Write down Newton's formula for the force of gravity.

a)

b)                                                                 

c)                                                               

d)                                                               

  10.  How did astronomical observations benefit ancient societies?

a) Allow them to predict war winners

b) Keeping track of time and seasons; navigation

c) Allow them to know the future names of kings

d) That way they knew the numbers of the winning lottery tickets