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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
  1. About asteroids hitting Earth.
  2. The swirling of water in a draining tub.
  3. Dispensing water at zero-g.
  4. Robert Goddard and World War II.
  5. Asymmetry of the Moon's orbit.
  6. Measuring distance from the Sun.
  7. Who owns the Moon?
  8. Acceleration of a rocket.
  9. Rebounding ping pong balls (re. #35)
  10. Rebounding ping pong balls and gravity-assist
  11. Why don't we feel the Sun's gravity pull?
  12. How hot are red, white and blue (etc.) stars?
  13. How does the solar wind move?
  14. The shape of the orbit of Mars
  15. What if the Earth's axis were tilted 90° to the ecliptic?

  16. Mars and Venus
  17. Where is the boundary between summer and winter?
  18. The Ozone Hole
  19. What keeps the Sun from blowing up?
  20. Those glorious Southern Skies!
  21. Should we fear big solar outbursts?
  22. Planetary line-up and the sunspot cycle
  23. What are comet tails made of?
  24. If light speed sets the limit, why fly into space?
  25. Does precession mis-align ancient monuments?
  26. Why does the Earth rotate? Why is it a sphere?
  27. What's so hard about reaching the Sun?

  28. Where does space begin?
  29. Gravity at the Earth's Center
  30. Radiation hazard in space (3 queries)
  31. "Danger, falling satellites"?
  32. The Lagrangian L3 point
  33. Distance to the Horizon on an Asteroid
  34. Overtaking Planets
  35. Falling Towards the Sun
  36. The Polar Bear
  37. Are the Sun's Rays Parallel?
  38. More thrust in reverse than going forward?
  39. The varying distance between Earth and Sun
  40. Mission to Mars
  41. Kepler's calculation
  42. The Appearance (Phase) of the Moon

  43. Stability of Lagrangian points
  44. Can an Asteroid Impact Change the Earth's Orbit?
  45. Can Gravity Increase with Depth?
  46. Lightspeed, Hyperspace and Wormholes
  47. Why do Rockets Spin?
  48. Around What does the Sun Revolve?
  49. Why are planets in nearly the same plane?
  50. The Shapes of Rockets and Spacecraft
  51. Space Debris
  52. Teaching Nuclear Fusion
  53. Contribution of different elements to Sunlight
  54. Jewish Calendar
  55. Spaceflight Without Escape Velocity?
  56. Who first proposed a round Earth?
  57. Does Precession change the Length of a Year?
  58. The Analemma
  59. Changes of the Polar Axis of Earth
  60. Van Allen Belt and Spaceflight
  61. Nearest Star Outside Our Galaxy
  62. (a) Why are Satellites Launched Eastward?
          What is a "Sun Synchronous" orbit?
     (b) Why are satellites launched from near the equator?
  63. How Tall Can People Get?
  64. Gunpowder and Rockets
  65. Precession
  66. Solar Sails
  67. (a) Distance to the Big Dipper
     (b) Big Dipper star names

  68. Was Moon landing a hoax?
  69. Clockwise or counter-clockwise?
  70. Isotopes in Center of Earth
  71. Density of the Sun's corona and the "Scale Height"
  72. Did Tesla extract free energy from thin air?
  73. What does "lapse rate" mean?
  74. Motion of the Sun through space
  75. Teaching about tides
  76. Distance to the Horizon
  77. Can geocentrist theory still be possible?
  78. Can Earth's rotation reverse, like its magnetic polarity?
  79. Why is the Earth round?
  80. The De Laval Nozzle
  81. Why 23.5 degrees?
  82. What is Gravitational Collapse?
  83. Can Earth capture a second moon?

  84. How far does the Earth's gravity extend?
  85. How far is the Moon?
  86. Twinkle, twinkle little star-- How I wonder, what you are.
  87. Teaching about seasons
  88. Space Launches by Cannon--A
  89. Space Launches by Cannon--B
  90. The Southern Pole of the Sky
  91. Do Astrologers use Wrong Positions for Planets?
  92. Why does the Moon have bigger craters?
  93. Why does Gravity Exist?
  94. Atmospheric "Thermals"--Triggered by Electric Forces?
  95. What would happen if Earth rotated faster?
  96. Where do gravity of Earth and Sun balance?
  97. The Ultimate Astronomy Tool
  98. High Temperature in Cold Outer Space

  99.   Refraction of sunlight and starlight by the atmosphere
  100.   Advice to a would-be astronomer
  101.   The effect of the Color of Light on the Output of Solar Cells
  102.   What is "radiation"?
  103.   Height of the Atmosphere
  104.   How does the upper atmosphere get so hot?
  105.   History of the use of De Laval's nozzle on rockets
  106.   Why don't Space Rockets use Wings?
  107. Distance of horizon on Mars
  108. Stopping the rotation of Earth?
  109. The equation of a parabola
  110. When does Jewish Sabbath start in the far north?
  111. Where is the center of the global landmass?
  112. What if our Sun was a much hotter star?
  113. Finding the north direction

  114. Why not use a heat shield going up?
  115. When and where can rainbows be seen?
  116. The unusual rotation of the planet Venus
  117. Why not use nuclear power for spaceflight?
  118. "Doesn't heat rise?"
  119. Have any changes been observed on the Moon?
  120. Why isn't our atmosphere flung off by the Earth's rotation?
  121. Can kinetic energy be reconverted to work?
  122. Does any location get the same number of sunshine hours per year?
  123. Speed of toy car rolling off an inclined ramp
  124. Acceleration due to gravity

  125. Re-entry from Space
  126. Balancing a Bicycle
  127. Is Absolute Zero reached on the Moon?
  128. Why isn't Longitude measured from 0° to 360°? "Constellation" or "Asterism"?
  129. "Position of the Stars when I was Born"
  130. Rotation of the Earth's Core"
  131. How hot is the Sun?
  132. How much weaker is gravity higher up?
  133. Eclipse of Venus?
  134. The Big Bang

  135. Thanks for the "Math Refresher" in Spanish
  136. The Pressure of Sunlight
  137. How is the instant the seasons change determined?
  138. Operation of Ion Rockets
  139. Physical Librations of the Moon
  140. The De-Laval Nozzle
  141. Why does the space shuttle rotate at take-off?
  142. Cold Fusion
  143. What if a Neutron Star hit the Sun?
    Why did the Moon appear Red?
  144. Centrifuge for Whirling Astronauts
  145. What Holds Galaxies Together?
  146. View of Earth and Moon from Mars
  147. Appearance of the Moon (1)
  148. Appearance of the Moon (2): Does it "roll around"?
  149. Altitude of the tail of the Big Dipper
  150. Sudden decompression, 5 miles up

  151. Do Negative Ions make you Feel Good?
  152. Shape of the Earth's Orbit
  153. Questions about the Solar Corona:
  154.                    (1) Why don't its particles separate by weight?
                       (2) What accelerates the solar wind?
  155. Why does the rising Sun look so big?
  156. Drawing a Perpendicular Line in Rectangular Coordinates
  157. Unequal Seasons
  158. Is the Big Dipper visible from Viet Nam?
  159. Holes in a Solar Sail
  160. Consequences of no more solar X-rays
  161. Science Fair Project on the Size of the Earth
  162. Superposition of Waves
  163. The Sun and Seasons
  164. If the Earth's Rotation would   S t o p...     (1)
  165. If the Earth's Rotation would   C h a n g e...     (2)
  166. What if the Earth stopped in its orbit?
  167. Fast Trip to Mars     (1)
  168. Fast Trip to Mars     (2)

  169. Spacecraft Attitude
  170. What makes the Earth rotate?
  171. Energy from the Earth's Rotation?
  172. How were planets created?
  173. Does Precession of the Equinoxes shift our Seasons?
  174. "Zenial Days" on Hawaii
  175. Sun's Temperature and Energy Density of Sunlight
  176. Teaching about energy in 8th grade
  177. About the jetstream
  178. What would a breach in a space station do?
  179. Gravity at the Earth's center
  180. Freak waves on the ocean
  181. Citation on "Bad Greenhouse" web page
  182. How can radio waves carry sound?
  183. Do Cosmic Rays produce lightning?
  184. Star positions shifted by the atmosphere
  185. The equation of time
  186. Launch window of the Space Shuttle

  187. No "Man in the Moon" from Australia?
  188. Picturing the Sun from a different distance
  189. What makes the sun shine so brightly?
  190. Re-entry from orbit
  191. Effects of weightlessness on one's body
  192. Blimps on Mars
  193. Planet Mars "huge" in the sky, in August 2005?
  194. Astronomy and telescopes for ones' own children
  195. Does the solar wind have escape velocity
  196. Astronomy for cliff-dwellers of New York City
  197. Portable star finder
  198. What if the Moon was closer? (2 questions)
  199. Why doesn't the Moon have an atmosphere?
  200. Telling a 3-year old about the atmosphere (2 questions)
  201. Three-color vision

  202. Superconductors work, universe expands--with no energy input. Why?
  203. Shuttle orbit and Earth rotation
  204. Worrying about Wormholes and Black Holes
  205. What should I study?
  206. The greenhouse effect
  207. Separation between lines of latitude and longitude
  208. Motion of air: hot to cold, or high pressure to low?
  209. Removing "Killer Asteroids"
  210. Strange light seen from Hawaii
  211. Is the Sun attached to another star?
  212. What if the Sun turned into a black hole?
  213. Do absorption lines have a Doppler shift?
  214. What are "Electromagnetic Waves"?
  215. Why are the two daily tides unequal?
  216. Why air gets cold higher up--a wrong explanation

  217. Any limits to Newton's 2nd Law
  218. Gravity at the Earth's center
  219. Does the Earth follow a "squiggly" orbit?
  220. Third grader asks: how far to zero gravity?
  221. "How does inertia affect a rolling ball"?
  222. What determines the quality of a telescope?
  223. Why design maps around curved lines?
  224. "Drag" by the Sun on the Earth's motion

  225. Does precession affect the time of summer? (2 questions)
  226. Newton's law or Bernoulli's?
  227. Does the universe have an axis?
  228. Frictional electricity
  229. Syllabus for catching up on physics
  230. Parabolic reflector
  231. At what distance does Earth start looking spherical?
  232. Is the Sun on fire?
  233. Confusion about the "Big Bang"
  234. How did Tycho calibrate his instruments?

  235. Gases that fill balloons
  236. Asian tradition on the start of winter
  237. Why our year starts at January 1
  238. Sticking a hand out of a window...
  239. One year of continuous sunlight?
  240. Shielding out radio waves
  241. The way gravity changes with depth
  242. The Sun's Axis
  243. "Gravity Particles"?
  244. A "short stay on Mars"
  245. Weight and mass
  246. "The Moon Hoax"
  247. Shuttle re-entry from space
  248. Energy levels: plus or minus?
  249. How can such small targets be accurately hit so far away?
  250. A teacher asks about compiling lesson plans
  251. Why the Moon has its phases
  252. How can a spacecraft self-rotate?
  253. Stability during a rocket launch
  254. Boiling point of water in space

  255. Konstantin Tsiolkovsky
  256. The Color Indigo
  257. Electromagnetic Waves and Electromagnetic Induction
  258. Why do orbits curve?
  259. The "Sundial Bridge" in Redding
  260. (a) Temperature in space
      (b) Exposure to the space environment: Freeze or burn?
  261. Remote sensing of Thunderstorms
  262. What keeps Electrons away from the Atomic Nucleus?
  263. The Stars on the Winter Solstice of 2012
  264. Mars Sunset
  265. Gravity at the Center of Earth
  266. The Big Bang
  267. "How Often are Stars Born?"
  268. The Path of Lightning
  269. Launching a Rocket from an Airplane
  270. The Equation of Continuity
  271. The Four Corners Monument
  272. Which among the brightest stars is closest to N Pole?
  273. Gravity Assist
  274. Is the Centrifugal Force "Real"?
  275. How do we know Earth is bigger than the Moon?
  276. Sound Waves on the Sun?
  277. What if we had to give up use of Satellites?
  278. Rotation of Venus
  279. "Proper Motion" of Stars
  280. Doppler Shift from the Big Bang
  281. Science Fiction scenario for a Flight to Mars
  282. Motion of the Moon

  283. "Iridium" flares
  284. Discovering Planets outside the Solar System
  285. Landing speed of airplane
  286. The Hubble Constant
  287. Are Summer Nights Darker?
  288. "Space Elevator"
  289. Black Holes
  1. Don't use Diesel fuel in a gasoline car!
  2. How bright is our Sun when seen from space?
  3. What is a "field"?
  4. Outer limits of the Solar System
  5. Gravitational Energy
  6. Stresses on a Railroad Bridge
  7. The constellation of Cassiopeia
  8. Tracking of radioactivity carried by winds
  9. Why can't the space shuttle reenter "slowly"?
  10. "The Standard Model of the Universe"
  11. About the Maya Calendar
  12. Are light sabers possible?
  13. Can the heat of sunshine make the Earth expand?

  14. About Mountains
  15. "Will the World end in 2012?" (a,b)
  16. Advice to graduating High School Student
  17. Could a (heat resistant!) ship float on the Sun?
  18. Reducing the fuel weight of the Space Shuttle?
  19. How do Rockets Land?
  20. The Earth's Spin reduced by Global Warming
  21. Circumnavigation of the Sun
  22. Are nuclear forces merely gravity at very close distance?
  23. Changing the Earth's Rotation
  24. Why are planetary orbits eccentric?
  25. Forces on Comet-dwellers
  26. Nuclear reactors and bombs
  27. Why doesn't magnetism affect electro-magnetic waves?
  28. Is humanity changing the climate, or is it the Sun and the Earth's magnetism?
  29. Advice to home-schooling parent
  30. Science of Clothing
  31. Calculating a Collision
  32. The Coriolis force and more
  33. Why isn't the solar system stratified by density?

  34. Tapping Atmospheric Electricity
  35. Global Disaster in 2012?
  36. What's the difference between speed and velocity?
  37. Effect of Gravity on Electromagnetic Waves
  38. Why is North the reference, not South?
  39. The lowest 700 km of our Atmosphere
  40. Doomsday 2012?
  41. Where does a Flying Bird get its Support?
  42. Why does Sun seem to move?
  43. Why don't waves disturb each other?
  44. Does the Moon's motion Change?
  45. Big Dipper and Weather
  46. What IS the Ecliptic?
  47. Precession, Greenhouse and more...
  48. Latest Sunrise, Earliest Sunset
  49. Falling off the Earth's Bottom?
  50. Rolling down a slope
  51. Pelton Wheel Efficiency
  52. Energy loss rate of our Sun
  53. The Sun's distance
  54. Why does sunlight have a continuous spectrum?

  55. Harry Paul Sprain's perpetual Motion Device
  56. Can the plasma that fills space help spaceflight?
  57. Spiral arms of our galaxy
  58. What powers a glider?
  59. UFOs
  60. Maximum speed for propeller-driven airplane?
  61. The speed at which gravity spreads
  62. Layers of the Earth
  63. Why doesn't the sky fall on us?
  64. Imagine a non-rotating Earth
  65. Flying east with a 1° error
  66. US Flag on the Moon
  67. Rope stretched across a long lake...
  68. About studying electronics in the USA
  69. Publish Stargazers as a book?
  70. Charging of Earth by lightning:   +   or   –  ?
  71. If no stars were seen--could Earth's orbital motion be discovered?
  72. Local Solar Time in Iceland
  73. Is orbital motion same as free fall?
  74. Build a straight tower in warped space?

  75. The 2011-2 sunspot maximum
  76. Is Earth adding mass?
  77. Shape of a "bottle rocket"
  78. Fantasy spaceflight vs. reality
  79. Telling a 7-year old about stars "dying"
  80. (1) Why is lightning jagged?     (2) What did Tesla do?
  81. How can the north wall of my house be in sunlight?
  82. Heating the inside of Earth
  83. Dawning of the Age of Aquarius
  84. Why is hydrogen the fuel of choice?
  85. Gamma ray bursts
  86. Counter-clockwise swirling motion in the atmosphere
  87. Leap years on the Jewish calendar
  88. Earth axis tilt and climate (1)
  89. Earth axis tilt and climate (2)
  90. Does the Sun move?
  91. Can the Sun interfere with the visibility of the Big Dipper?
  92. Why can't we feel the Earth's rotation?
  93. Is our galaxy held together by a central black hole?
  94. Why don't gas planets just evaporate?
  95. Source of the Sun's energy
  96. Point of gravity equilibrium
  97. Solar system motion through the Galaxy
  98. Spaceflight by waiting for the Earth to turn?
  99. Does Earth rotation affect size of creatures?
  100. The year 2012
  101. Are our galactic arms winding up or opening up?
  102. Advice to a home-schooling mother
  103. Are all stars we see suns?

  104. Newton's 3rd law
  396A Posssibility of Asteroid Hitting Earth (1)
  396B Posssibility of Asteroid Hitting Earth (2)
  1. Author's IQ
  2. Global Warming caused by Sun getting nearer?
  3. The year 2012
  4. Empty space behind North Star?
  5. The year 2012 and the 26,000 year cycle
  6. "Quarter Squares"
  7. Do Rockets need "something to push against"?
  8. Sunrise-Sunset asymmetry
  9. Re-entry from orbit
  10. Earth Axis and Gravity
  11. The year 2012
  12. Choosing an Aerospace Career
  13. Advice for "new" physics teacher
  14. Paradox of Time Travel
  15. Is 7th grade Earth science boring?
  16. Air Resistance
  17. Experimenting with Microwave Oven
  18. Is the Sun losing mass?
  19. Sun's position at noon, south of equator
  20. Fred Hoyle's theory of the Sun's Corona
  21. Why don't Protons and Electrons combine?
  22. Days in a Year
  23. Position of the Moon in the sky

  24. Earth crossing Galactic Equator?
  25. Is the geocentric theory ruled out?
  26. Does the Southern Sky have a Pole Star?
  27. What is the fate of starlight energy?
  28. Double-slit diffraction of particles
  29. Does the Sun overhead reduce effective weight?
  30. Evidence for Global Warming ?
  31. Distances to the Equator
  32. Weight on the Equator and at the Pole
  33. Why doesn't gravity overcome buoyancy?
  34. The Prime Meridian
  35. Is L2 in the Earth's Shadow?
  36. In what direction is Israel from NY?
  37. Is the World Overpopulated?
    Magnetic Energy
  38. Magnetic Carnot Cycle
  39. Defining the Equator

  40. Second Moon for Earth?
  41. The year 2012 and a distant companion of our Sun
  42. Distance between two points on a sphere
  43. Getting sucked n by Gravity
  44. The work of Nikola Tesla
  45. Firing a cannon straight up
  46. Does one see half the sky--or more, or less?
  47. Why are nights dark?
  48. The origin of the Solar System
  49. Flying to other planets
  50. The heat of the Sun's corona
  51. Crossing our galaxy's equator
  52. Newton's 3rd law--in statics and dynamics
  53. Barycenter of Earth-Moon system
  54. What if Earth rotated in only 10 hours

  55. What Book covers material of "Stargazers"?
  56. Climate Change
  57. A classroom Demonstration
  58. Why doesn't the Solar System Collapse?
  59. A Diamond Core for Jupiter?
  60. Why no "artificial gravity" on the space station?
  61. Precession of the axis of Mars
  62. Does the axis of the Sun precess?
  63. Can a microwave oven produce 900 deg Celsius?
  64. Beaming energy through space
  65. The year 2012
  66. The Earth's Precession Cycle
  67. The empty space inside an atom

  68. Rotation of Galaxies
  69. Sailplane flight
  70. How far to the Pole Star?
  71. Missed Discoveries
  72. Independent study for bright students
  73. Double slit interference experiment in space
  74. Ionizing Radiation and the Origin of Life
  75. On Earth's spin and Moon's appearance
  76. Back to the Geocentric Universe?
  77. Radiation risks from uranium counterweights
  78. The centrifugal force from Earth's rotation
  79. Earth's rotation and human lifespan
    Dependence of cosmic redshifts on direction
  80. Difference between Gravity and Magnetism
  81. SciFi world with ahort days and long nights
  82. Celestial Equator and Ecliptic Equator
  83. Cavendish gravity constant G drops out
  84. Teacher seeks material
  85. Solar Sails
  86. Life under stronger gravity
  87. Message from Kansas
    Finding true north in an underground mine
  88. Aristarchus
  89. Calculation of Gravity
  90. Message from Michigan
  91. Confused about "Temperature"
  92. "Negative work" and energy
  93. The Coriolis force on a moving air mass
  94. Recent change in sunset?
  95. Space and Dark Matter
  96. Newton's 3rd law
  97. Shift of Earth Axis in 2012?
    Ptolemaic Theory of Planet Motion
  98. Electricity from Earth's Rotation?
  99. Change in Earth's gravity after Tsunamis
  100. Science fair expt. on light output of CFLs
  101. Does iron 56Fe have the most stable nucleus?
  102. "Black Light Telescope"
  103. Message from New Jersey

Go to main list of questions   (by topic)

Author and Curator:   Dr. David P. Stern
     Mail to Dr.Stern:   stargaze("at" symbol)phy6.org .

Last updated 2-25-2012

Above is background material for archival reference only.

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