You are here:

Astronomy/During Ptolemy's time the universe was geocentric: What makes this statement valid?


During Ptolemy's time the universe was geocentric. Write a convincing argument that this statement is valid.

First, it is intuitively obvious (to the uninformed back then) that the Earth was flat, solid,  unmoving, and in the center as it seems that everything revolves around the Earth... the night sky, moon, and sun... on a big inverted bowl or dome, overhead. The successful argument can be used that if the Earth was moving, the winds would be so strong that no one would survive.  Thus nature easily "fooled" them into thinking that the Earth was solid, flat, stationary, and in the center of everything, as everything "appeared" to revolve around the stationary Earth.  Of course, we know today that not one of those items above are true.  Nature can really fool us, even today. It's only been about 15 years that we discovered that spacial expansion is actually accelerating outward, and not slowing or decelerating, as we thought until 1998!
(And this leads to the invention of Dark Energy, but that's another story).
 And this geocentric unmoving Earth concept held sway until Copernicus in the 16th century, so it was a very powerful argument... but of course, wrong.
Plus, the Bible, in a way, substantiated the central, unmoving Earth... I believe it was Joshua that asked the Lord to make the SUN stand still at the battle of (?)... and not the Earth.
There is a Psalm that states, in so many words, that the foundations of the Earth are laid that it be unmoved forever.
There is also a biblical reference about the Earth hanging as on a string in nothing... implying a stationary aspect to the Earth itself, but I slept through that theological class.
Hope this helps,  
Clear Skies,
Tom Whiting
Erie, PA  


All Answers

Answers by Expert:

Ask Experts


Tom Whiting


Astronomy has been my hobby/pasttime for over 50 years.  Currently own 3 telescopes, the largest of which is a 30 inch Newtonian truss Dob that is portable.I taught Astronomy/Meteorology at the University Level for 13 years before retiring in 1995. Being retired and home most of the time, I am able to answer all questions relatively quickly, unless it's a new moon weekend with good observing conditions.  No astrology questions please, or questions about alleged UFO picture identifications.


Experience: Astronomy has been my hobby and study for over 50 years. We currently now own a 30 inch portable telescope (Updated - Pennsylvania`s largest portable telescope). It can be seen on our website at: and also attend several regional starparties during the year, and have been on 5 total solar eclipse expeditions.

Organizations: President, Erie County Mobile Observers Group for over 15 years.

Publications: Wrote the "Over Erie Skies" newspaper article in our local newspaper for 11 years (1975-86).

Education: Masters Degree- Taught at the University level for 13 years. Retired 20 years -USAF Pilot - KC-135 with 180 combat missions;  Also Eagle Scout, Philmont staff 2 Yrs, Order of Arrow Lodge Chief, Ham Radio (inactive).

Awards: two discoveries: The mini-coathanger asterism in Ursa Minor (the little dipper) And the mini-ladle- another asterism in the bowl of Ursa Minor. Clients: Currently President of the ECMOG as mentioned above.

BS  Metallurgical Engineering Grove City College, PAMaster's Degree, Gannon University, Erie, PA Also retired USAF pilot, 20 years.

©2017 All rights reserved.