Please note!
     Listed below are questions submitted over about 14 years by users of "From Stargazers to Starships," posted together with their answers. This is just a selection from the many questions that arrive.  They were included because either they are the sort that keeps being asked again and again, or else the answers make a special point, often going into details which might interest many users. 
   This is a complete list, over 500 items (so far), and because of its length it is given here separately, in the order submitted.  A complete list sorted by topic area is in file               http://www.phy6.org/stargaze/StarFSubj.htm
.  Either list is linked to all the messages, collected in 26 separate files to speed up access.
                                                       David P. Stern       25 February 2012
 
 
- About asteroids hitting Earth.
 
- The swirling of water in a draining tub.
 
- Dispensing water at zero-g.
 
- Robert Goddard and World War II.
 
- Asymmetry of the Moon's orbit.
 
- Measuring distance from the Sun.
 
- Who owns the Moon?
 
- Acceleration of a rocket.
 
- Rebounding ping pong balls (re. #35)
 
- Rebounding ping pong balls and gravity-assist
 
- Why don't we feel the Sun's gravity pull?
 
- How hot are red, white and blue (etc.) stars? 
 
- How does the solar wind move? 
 
- The shape of the orbit of Mars
 
- What if the Earth's axis were tilted 90° to the ecliptic?
 
  
-  Mars and Venus 
 
-  Where is the boundary between summer and winter?
 
-  The Ozone Hole 
 
-  What keeps the Sun from blowing up?
 
-  Those glorious Southern Skies!
 
- Should we fear big solar outbursts?
 
- Planetary line-up and the sunspot cycle
 
- What are comet tails made of?
 
- If light speed sets the limit, why fly into space?
 
- Does precession mis-align ancient monuments?
 
- Why does the Earth rotate? Why is it a sphere?
 
- What's so hard about reaching the Sun?
 
  
- Where does space begin?
 
- Gravity at the Earth's Center 
 
- Radiation hazard in space (3 queries)
 
- "Danger, falling satellites"?
 
- The Lagrangian L3 point
 
-  Distance to the Horizon on an Asteroid 
 
-  Overtaking Planets 
 
-  Falling Towards the Sun 
 
-  The Polar Bear 
 
-  Are the Sun's Rays Parallel?
 
-  More thrust in reverse than going forward?
 
-  The varying distance between Earth and Sun 
 
-  Mission to Mars 
 
- Kepler's calculation
 
-  The Appearance (Phase) of the Moon
 
  
-  Stability of Lagrangian points 
 
-  Can an Asteroid Impact Change the Earth's Orbit?
 -  Can Gravity Increase with Depth?
 
-  Lightspeed, Hyperspace and Wormholes
 
-  Why do Rockets Spin?
 
-  Around What does the Sun Revolve? 
 
-  Why are planets in nearly the same plane?
 
-  The Shapes of Rockets and Spacecraft 
 
- Space Debris 
 
- Teaching Nuclear Fusion 
 
- Contribution of different elements to Sunlight 
 
- Jewish Calendar 
 
- Spaceflight Without Escape Velocity?
 
- Who first proposed a round Earth? 
 
- Does Precession change the Length of a Year? 
 
- The Analemma 
 
- Changes of the Polar Axis of Earth 
 
- Van Allen Belt and Spaceflight 
 
- Nearest Star Outside Our Galaxy
 
- (a) Why are Satellites Launched Eastward? 
 
      What is a "Sun Synchronous" orbit?  
 (b) Why are satellites launched from near the equator?
  
-  How Tall Can People Get? 
 
-  Gunpowder and Rockets 
 
-  Precession 
 
-  Solar Sails 
 
- (a) Distance to the Big Dipper 
 
 (b) Big Dipper star names 
 
  
-  Was Moon landing a hoax? 
 
-  Clockwise or counter-clockwise? 
 
-  Isotopes in Center of Earth 
 
-  Density of the Sun's corona and the "Scale Height"
 
-  Did Tesla extract free energy from thin air? 
 
- What does "lapse rate" mean? 
 
- Motion of the Sun through space 
 
- Teaching about tides 
 
- Distance to the Horizon 
 
- Can  geocentrist theory still be possible? 
 
- Can Earth's rotation reverse, like its magnetic polarity?  
 
- Why  is the Earth round?  
 
-  The De Laval Nozzle  
 
-  Why 23.5 degrees?  
 
-  What is Gravitational Collapse?  
 
-  Can Earth capture a second moon?
 
  
- How far does the Earth's gravity extend?  
 
-  How far is the Moon?
 
-  Twinkle, twinkle little star--
How I wonder, what you are.
 
-  Teaching about seasons 
 
-  Space Launches by Cannon--A 
 
-  Space Launches by Cannon--B 
 
-  The Southern Pole of the Sky 
 
-  Do Astrologers use Wrong Positions for Planets?  
 
-  Why does the Moon have bigger craters?  
 
-  Why does Gravity Exist? 
 
-  Atmospheric "Thermals"--Triggered by Electric Forces?
 
-  What would happen if Earth rotated faster?
 
-  Where do gravity of Earth and Sun balance?
 
-  The Ultimate Astronomy Tool 
 
-  High Temperature in Cold Outer Space 
 
  
-    Refraction of sunlight and starlight by the atmosphere 
 
-     Advice to a would-be astronomer 
 
-    The effect of the Color of Light on the Output of Solar Cells 
 
-    What is "radiation"?
 
-    Height of the Atmosphere  
 
-    How does the upper atmosphere get so hot?     
 
-    History of the use of De Laval's nozzle on rockets 
 
-    Why don't Space Rockets use Wings?   
 
- Distance of horizon on Mars 
 
- Stopping the rotation of Earth?
 
- The equation of a parabola
 
- When does Jewish Sabbath start in the far north?
 
- Where is the center of the global landmass?
 
- What if our Sun was a much hotter star?
 
- Finding the north direction 
 
  
-  Why not use a heat shield going up?
 
- When and where can rainbows be seen?
 
-  The unusual rotation of the planet Venus 
 
-  Why not use nuclear power for spaceflight?
 
- "Doesn't heat rise?"
 
- Have any changes been observed on the Moon?
 
-  Why isn't our atmosphere flung off by the Earth's rotation?
 
- Can kinetic energy be reconverted to work?  
 
- Does any location get the same number of sunshine hours per year?
 
-  Speed of toy car rolling off an inclined ramp
 
-  Acceleration due to gravity 
 
  
- Re-entry from Space 
 
- Balancing a Bicycle
 
- Is Absolute Zero reached on the Moon?
 
-  Why isn't Longitude measured from 0° to 360°? "Constellation" or "Asterism"?
 
- "Position of the Stars when I was Born"
 
- Rotation of the Earth's Core"
 
- How hot is the Sun?
 
- How much weaker is gravity higher up?
 
- Eclipse of Venus?
 
- The Big Bang
 
  
- Thanks for the "Math Refresher" in Spanish 
 
- The Pressure of Sunlight
 
- How is the instant the seasons change determined?
 
- Operation of Ion Rockets
 
- Physical Librations of the Moon
 
- The De-Laval Nozzle
 
- Why does the space shuttle rotate at take-off?
 
- Cold Fusion
 
- What if a Neutron Star hit the Sun?
 Why did the Moon appear Red? 
-  Centrifuge for Whirling Astronauts 
 
- What Holds Galaxies Together?
 
- View of Earth and Moon from Mars
 
- Appearance of the Moon (1)
 
- Appearance of the Moon (2): Does it "roll around"?
 
- Altitude of the tail of the Big Dipper  
 
- Sudden decompression, 5 miles up 
 
  
- Do Negative Ions make you Feel Good? 
 
- Shape of the Earth's Orbit 
 
- Questions about the Solar Corona: 
 
                  
(1) Why don't its particles separate by weight? 
                  
(2) What accelerates the solar wind?
- Why does the rising Sun look so big? 
 
- Drawing a Perpendicular Line in Rectangular Coordinates 
 
- Unequal Seasons 
 
- Is the Big Dipper visible from Viet Nam? 
 
- Holes in a Solar Sail 
 
- Consequences of no more solar X-rays 
 
- Science Fair Project on the Size of the Earth
 
- Superposition of Waves 
 
- The Sun and Seasons 
 
- If the Earth's Rotation would   S t o p...       (1) 
 
- If the Earth's Rotation would   C h a n g e...       (2) 
 
- What if the Earth stopped in its orbit? 
 
- Fast Trip to Mars      (1) 
 
- Fast Trip to Mars      (2) 
 
  
- Spacecraft Attitude
 
- What makes the Earth rotate?
 
- Energy from the Earth's Rotation?
 
- How were planets created?
 
- Does Precession of the Equinoxes shift our Seasons?
 
- "Zenial Days" on Hawaii
 
- Sun's Temperature and Energy Density of Sunlight
 
- Teaching about energy in 8th grade
 
- About the jetstream 
 
- What would a breach in a space station do? 
 
- Gravity at the Earth's center  
 
- Freak waves on the ocean  
 
- Citation on "Bad Greenhouse" web page 
 
- How can radio waves carry sound? 
 
- Do Cosmic Rays produce lightning? 
 
- Star positions shifted by the atmosphere 
 
-  The equation of time  
 
- Launch window of the Space Shuttle 
 
  
- No "Man in the Moon" from Australia? 
 
- Picturing the Sun from a different distance 
 
- What makes the sun shine so brightly? 
 
- Re-entry from orbit 
 
- Effects of weightlessness on one's body 
 
- Blimps on Mars 
 
- Planet Mars "huge" in the sky, in August 2005? 
 
- Astronomy and telescopes for ones' own children 
 
- Does the solar wind have escape velocity 
 
- Astronomy for cliff-dwellers of New York City  
 
- Portable star finder 
 
- What if the Moon was closer? (2 questions) 
 
- Why doesn't the Moon have an atmosphere? 
 
- Telling a 3-year old about the atmosphere  (2 questions) 
 - Three-color vision 
 
  
- Superconductors work, universe expands--with no energy input. Why? 
 
- Shuttle orbit and Earth rotation 
 
- Worrying about Wormholes and Black Holes 
 
- What should I study? 
 
- The greenhouse effect 
 
- Separation between lines of latitude and longitude 
 
- Motion of air: hot to cold, or high pressure to low? 
 
- Removing "Killer Asteroids" 
 
- Strange light seen from Hawaii 
 
- Is the Sun attached to another star? 
 
- What if the Sun turned into a black hole? 
 
- Do absorption lines have a Doppler shift? 
 
- What are "Electromagnetic Waves"? 
 
- Why are the two daily tides unequal? 
 
- Why air gets cold higher up--a wrong explanation 
 
  
- Any limits to Newton's 2nd Law 
 
- Gravity at the Earth's center 
 
- Does the Earth follow a "squiggly" orbit? 
 
- Third grader asks: how far to zero gravity? 
 
- "How does inertia affect a rolling ball"? 
 
- What determines the quality of a telescope? 
 
- Why design maps around curved lines? 
 
- "Drag" by the Sun on the Earth's motion 
 
 
- Does precession affect the time of summer? (2 questions) 
 
- Newton's law or Bernoulli's? 
 
- Does the universe have an axis? 
 
- Frictional electricity 
 
- Syllabus for catching up on physics 
 
- Parabolic reflector 
 
- At what distance does Earth start looking spherical? 
 
- Is the Sun on fire? 
 
- Confusion about the "Big Bang" 
 
- How did Tycho calibrate his instruments? 
 
  
- Gases that fill balloons 
 
- Asian tradition on the start of winter 
 
- Why our year starts at January 1 
 
- Sticking a hand out of a window... 
 
- One year of continuous sunlight?
 
- Shielding out radio waves 
 
- The way gravity changes with depth 
 
- The Sun's Axis 
 
- "Gravity Particles"? 
 
- A "short stay on Mars" 
 
- Weight and mass 
 
- "The Moon Hoax" 
 
- Shuttle re-entry from space 
 
- Energy levels: plus or minus? 
 
- How can such small targets be accurately hit
so far away? 
 
- A teacher asks about compiling lesson plans 
 
- Why the Moon has its phases 
 
- How can a spacecraft self-rotate? 
 
- Stability during a rocket launch 
 
- Boiling point of water in space 
 
 
 - Konstantin Tsiolkovsky 
 
 - The Color Indigo 
 
 - Electromagnetic Waves and Electromagnetic Induction 
 
 - Why do orbits curve? 
 
 - The "Sundial Bridge" in Redding 
 
 - (a) Temperature in space 
 
  
(b) Exposure to the space environment: Freeze or burn? 
 - Remote sensing of Thunderstorms 
 
 - What keeps Electrons away from the Atomic Nucleus? 
 
 - The Stars on the Winter Solstice of 2012 
 
 - Mars Sunset 
 
 - Gravity at the Center of Earth 
 
 - The Big Bang 
 
 - "How Often are Stars Born?" 
 
 - The Path of Lightning 
 
 - Launching a Rocket from an Airplane 
 
 - The Equation of Continuity 
 
 - The Four Corners Monument 
 
 - Which among the brightest stars is closest to N Pole? 
 
 - Gravity Assist 
 
 - Is the Centrifugal Force "Real"? 
 
 - How do we know Earth is bigger than the Moon? 
 
 - Sound Waves on the Sun? 
 
 - What if we had to give up use of Satellites? 
 
 - Rotation of Venus 
 
 - "Proper Motion" of Stars 
 
 - Doppler Shift from the Big Bang 
 
 - Science Fiction scenario for a Flight to Mars 
 
 - Motion of the Moon 
 
  
 - "Iridium" flares 
 
 - Discovering Planets outside the Solar System 
 
 - Landing speed of airplane 
 
 - The Hubble Constant 
 
 - Are Summer Nights Darker? 
 
 - "Space Elevator" 
 
 - Black Holes 
 
  
- Don't use Diesel fuel in a gasoline car! 
 
 - How bright is our Sun when seen from space? 
 
 - What is a "field"? 
 
 -  Outer limits of the Solar System  
 
 - Gravitational Energy
 
 - Stresses on a Railroad Bridge 
 
 - The constellation of Cassiopeia 
 
 - Tracking of radioactivity carried by winds 
 
 - Why can't the space shuttle reenter "slowly"? 
 
 - "The Standard Model of the Universe" 
 
 - About the Maya Calendar 
 
 - Are light sabers possible? 
 
 - Can the heat of sunshine make the Earth expand? 
 
 
 - About Mountains 
 
 - "Will the World end in 2012?" (a,b)
 
 - Advice to graduating High School Student 
 
 - Could a (heat resistant!) ship float on the Sun?
 
 - Reducing the fuel weight of the Space Shuttle?
 
 - How do Rockets Land?
 
 - The Earth's Spin reduced by Global Warming
 
 - Circumnavigation of the Sun
 
 - Are nuclear forces merely gravity at very close distance?
 
 - Changing the Earth's Rotation
 
 - Why are planetary orbits eccentric?
 
 - Forces on Comet-dwellers
 
 - Nuclear reactors and bombs
 
 - Why doesn't magnetism affect electro-magnetic waves?
 
 - Is humanity changing the climate, or is it the Sun and the Earth's magnetism?
 
 - Advice to home-schooling parent
 
 - Science of Clothing
 
 - Calculating a Collision
 
 - The Coriolis force and more
 
 - Why isn't the solar system stratified by density?
 
 
 - Tapping Atmospheric Electricity
 
 - Global Disaster in 2012?
 
 - What's the difference between speed and velocity?
 
 - Effect of Gravity on Electromagnetic Waves 
 
 - Why is North the reference, not South?   
 
 - The lowest 700 km of our Atmosphere 
 
 - Doomsday 2012?
 
 - Where does a Flying Bird get its Support?
 
 - Why does Sun seem to move?
 
 -  Why don't waves disturb each other?
 
 - Does the Moon's motion Change?
 
 - Big Dipper and Weather
 
 - What IS the Ecliptic?
 
 - Precession, Greenhouse and more...   
 
 - Latest Sunrise, Earliest Sunset
 
 - Falling off the Earth's Bottom?
 
 - Rolling down a slope
 
 - Pelton Wheel Efficiency
 
 - Energy loss rate of our Sun
 
 - The Sun's distance
 
 - Why does sunlight have a continuous spectrum?
  
 - Harry Paul Sprain's perpetual Motion Device
 
 - Can the plasma that fills space help spaceflight?
 
 - Spiral arms of our galaxy
 
 - What powers a glider? 
 
 - UFOs
 
 - Maximum speed for propeller-driven airplane?
 
 - The speed at which gravity spreads  
 
 - Layers of the Earth
 
 - Why doesn't the sky fall on us?
 
 - Imagine a non-rotating Earth
 
 - Flying east with a 1° error
 
 - US Flag on the Moon 
 
 - Rope stretched across a long lake...
 
 - About studying electronics in the USA
 
 - Publish Stargazers as a book?
 
 - Charging of Earth by lightning:    +   or   –  ?
 
 - If no stars were seen--could Earth's orbital motion be discovered?
 
 - Local Solar Time in Iceland
 
 - Is orbital motion same as free fall?
 
 - Build a straight tower in warped space?
 
  
 - The 2011-2 sunspot maximum
 
 - Is Earth adding mass?
 
 - Shape of a "bottle rocket"
 
 - Fantasy spaceflight vs. reality
 
 - Telling a 7-year old about stars "dying"  
 
 - (1) Why is lightning jagged?     (2) What did Tesla do?
 
 - How can the north wall of my house be in sunlight?
 
 - Heating the inside of Earth
 
 - Dawning of the Age of Aquarius
 
 - Why is hydrogen the fuel of choice?
 
 - Gamma ray bursts
 
 - Counter-clockwise swirling motion in the atmosphere
 
 - Leap years on the Jewish calendar
 
 - Earth axis tilt and climate (1)
 
 - Earth axis tilt and climate (2)
 
 - Does the Sun move?
 
 - Can the Sun interfere with the visibility of the Big Dipper?
 
 - Why can't we feel the Earth's rotation?
 
 - Is our galaxy held together by a central black hole?
 
 - Why don't gas planets just evaporate?
 
 - Source of the Sun's energy
 
 - Point of gravity equilibrium
 
 - Solar system motion through the Galaxy 
 
 -  Spaceflight by waiting for the Earth to turn?
 
 - Does Earth rotation affect size of creatures?
 
 - The year 2012
 
 - Are our galactic arms winding up or opening up?
 
 -  Advice to a home-schooling mother 
 
 -  Are all stars we see suns?
 
 
 - Newton's 3rd law
 
  
   396A Posssibility of Asteroid Hitting Earth (1) 
  396B Posssibility of Asteroid Hitting Earth (2) 
- Author's IQ
 
 - Global Warming caused by Sun getting nearer?
 
 - The year 2012
 
 - Empty space behind North Star?
 
 - The year 2012 and the 26,000 year cycle
 
 - "Quarter Squares"
 
 - Do Rockets need "something to push against"?
 
 - Sunrise-Sunset asymmetry
 
 - Re-entry from orbit
 
 - Earth Axis and Gravity
 
 - The year 2012
 
 - Choosing an Aerospace Career
 
 - Advice for "new" physics teacher
 
 - Paradox of Time Travel
 
 - Is 7th grade Earth science boring?
 
 - Air Resistance
 
 - Experimenting with Microwave Oven
 
 - Is the Sun losing mass?
 
 - Sun's position at noon, south of equator
 
 - Fred Hoyle's theory of the Sun's Corona
 
 - Why don't Protons and Electrons combine?
 
 - Days in a Year
 
 - Position of the Moon in the sky
 
 
 - Earth crossing Galactic Equator?
 
 - Is the geocentric theory ruled out?
 
 - Does the Southern Sky have a Pole Star?
 
 - What is the fate of starlight energy?  
 
 - Double-slit diffraction of particles 
 
 - Does the Sun overhead reduce effective weight?
 
 -  Evidence for Global Warming ?  
 
 - Distances to the Equator 
 
 - Weight on the Equator and at the Pole 
 
 - Why doesn't gravity overcome buoyancy? 
 
 - The Prime Meridian 
 
 - Is L2 in the Earth's Shadow? 
 
 - In what direction is Israel from NY?
 
 - Is the World Overpopulated?   
 
 - Magnetic Energy
 
 - Magnetic Carnot Cycle
 
 - Defining the Equator
 
 
 - Second Moon for Earth?
 
 - The year 2012 and a distant companion of our Sun
 
 - Distance between two points on a sphere
 
 - Getting sucked n by Gravity
 
 - The work of Nikola Tesla
 
 - Firing a cannon straight up
 
 - Does one see half the sky--or more, or less?
 
 - Why are nights dark?
 
 - The origin of the Solar System
 
 - Flying to other planets
 
 - The heat of the Sun's corona
 
 - Crossing our galaxy's equator
 
 - Newton's 3rd law--in statics and dynamics
 
 - Barycenter of Earth-Moon system
 
 - What if Earth rotated in only 10 hours
 
 
 - What Book covers material of "Stargazers"? 
 
 - Climate Change
 
 - A classroom Demonstration
 
 - Why doesn't the Solar System Collapse? 
 
 - A Diamond Core for Jupiter? 
 
 - Why no "artificial gravity" on the space station? 
 
 - Precession of the axis of Mars
 
 - Does the axis of the Sun precess? 
 
 - Can a microwave oven produce 900 deg Celsius? 
 
 - Beaming energy through space
 
 - The year 2012
 
 - The Earth's Precession Cycle
 
 - The empty space inside an atom
 
 
 
 - Rotation of Galaxies
 
 - Sailplane flight
 
 - How far to the Pole Star?
 
 - Missed Discoveries
 
 - Independent study for bright students
 
 - Double slit interference experiment in space
 
 - Ionizing Radiation and the Origin of Life
 
 - On Earth's spin and Moon's appearance
 
 - Back to the Geocentric Universe?
 
 - Radiation risks from uranium counterweights
 
 - The centrifugal force from Earth's rotation
 
 - Earth's rotation and human lifespan
 
 - Dependence of cosmic redshifts on direction
 
 - Difference between Gravity and Magnetism
 
 - SciFi world with ahort days and long nights
 
 - Celestial Equator and Ecliptic Equator
 
 - Cavendish gravity constant G drops out
 
 - Teacher seeks material
 
 - Solar Sails
 
 - Life under stronger gravity
 
 - Message from Kansas
 
 - Finding true north in an underground mine
 
 - Aristarchus
 
 - Calculation of Gravity
 
 - Message from Michigan
 
 - Confused about "Temperature"
 
 - "Negative work" and energy
 
 - The Coriolis force on a moving air mass
 
 - Recent change in sunset?
 
 - Space and Dark Matter
 
 - Newton's 3rd law
 
 - Shift of Earth Axis in 2012?
 
 - Ptolemaic Theory of Planet Motion
 
 - Electricity from Earth's Rotation?
 
 - Change in Earth's gravity after Tsunamis
 
 - Science fair expt. on light output of CFLs
 
 - Does iron 56Fe have the most stable nucleus?
 
 - "Black Light Telescope"
 
 - Message from New Jersey
 
 
  
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