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Where did Ptolemy compare the Earth to the distance of fixed stars?
Planned maintenance scheduled April 23, 2019 at 23:30 UTC (7:30pm US/Eastern)
Announcing the arrival of Valued Associate #679: Cesar Manara
Unicorn Meta Zoo #1: Why another podcast?When was the airless void above the earth discovered?Who first distinguished planets from the stars?How Long Did It Take To Prove That The Earth Revolves Around The SunPlanets/stars as more than points of lightWhen did the estimates of planetary distances made between Ptolemy and Copernicus produce the pattern suggesting heliocentrism?Did the ancient Chinese know the earth is a sphere?When was it discovered that the Earth wasn't round?Historical knowledge of Distance of Earth from SunWhen did astronomy first discover that the stars are bigger than the moon?How did Ptolemy calculate the distance to the moon
$begingroup$
I read the following in C. S. Lewis, Miracles (page 77-8)
The immensity of the universe is not a recent discovery. More than seventeen hundred years ago Ptolemy taught that in relation to the distance of the fixed stars the whole Earth must be regarded as a point with no magnitude.
There was no reference given, but I assume this would be in the Almagest. However, I don't know where in that work (or elsewhere) Ptolemy discussed this. I want to read his explanation for that view.
Hence the question: Where did Ptolemy compare the Earth to the distance of fixed stars?
astronomy
New contributor
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add a comment |
$begingroup$
I read the following in C. S. Lewis, Miracles (page 77-8)
The immensity of the universe is not a recent discovery. More than seventeen hundred years ago Ptolemy taught that in relation to the distance of the fixed stars the whole Earth must be regarded as a point with no magnitude.
There was no reference given, but I assume this would be in the Almagest. However, I don't know where in that work (or elsewhere) Ptolemy discussed this. I want to read his explanation for that view.
Hence the question: Where did Ptolemy compare the Earth to the distance of fixed stars?
astronomy
New contributor
$endgroup$
add a comment |
$begingroup$
I read the following in C. S. Lewis, Miracles (page 77-8)
The immensity of the universe is not a recent discovery. More than seventeen hundred years ago Ptolemy taught that in relation to the distance of the fixed stars the whole Earth must be regarded as a point with no magnitude.
There was no reference given, but I assume this would be in the Almagest. However, I don't know where in that work (or elsewhere) Ptolemy discussed this. I want to read his explanation for that view.
Hence the question: Where did Ptolemy compare the Earth to the distance of fixed stars?
astronomy
New contributor
$endgroup$
I read the following in C. S. Lewis, Miracles (page 77-8)
The immensity of the universe is not a recent discovery. More than seventeen hundred years ago Ptolemy taught that in relation to the distance of the fixed stars the whole Earth must be regarded as a point with no magnitude.
There was no reference given, but I assume this would be in the Almagest. However, I don't know where in that work (or elsewhere) Ptolemy discussed this. I want to read his explanation for that view.
Hence the question: Where did Ptolemy compare the Earth to the distance of fixed stars?
astronomy
astronomy
New contributor
New contributor
New contributor
asked 7 hours ago
Frank HubenyFrank Hubeny
11316
11316
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2 Answers
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$begingroup$
Almagest, Book 1, chap. 5 ................
$endgroup$
$begingroup$
This basically answered my question where in the Almagest I need to look.
$endgroup$
– Frank Hubeny
1 hour ago
add a comment |
$begingroup$
Ptolemy's argument can be simply explained in plain English. If the distance to stars
was comparable to the size of the Earth, the stars would experience a diurnal parallax, that is the visible relative positions of the stars in the sky would change during one night. But this is not observed.
By the way, a similar argument will imply that if the Earth is rotating about the Sun
(or moves in some other way), the distance to the stars must be much larger than the size of this motion. In particular the diameter of the orbit of the Earth around the Sun is negligible in comparison to the distance to the stars.
This was the most serious argument against the Heliocentric system, and it is also
due to Ptolemy. Until the acceptance of Copernicus theory, people just could not believe that the distance to the stars can be so large.
$endgroup$
$begingroup$
Thank you for confirming that it was parallax and for connecting this to questions about the Heliocentric system.
$endgroup$
– Frank Hubeny
1 hour ago
add a comment |
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2 Answers
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$begingroup$
Almagest, Book 1, chap. 5 ................
$endgroup$
$begingroup$
This basically answered my question where in the Almagest I need to look.
$endgroup$
– Frank Hubeny
1 hour ago
add a comment |
$begingroup$
Almagest, Book 1, chap. 5 ................
$endgroup$
$begingroup$
This basically answered my question where in the Almagest I need to look.
$endgroup$
– Frank Hubeny
1 hour ago
add a comment |
$begingroup$
Almagest, Book 1, chap. 5 ................
$endgroup$
Almagest, Book 1, chap. 5 ................
answered 5 hours ago
sand1sand1
90957
90957
$begingroup$
This basically answered my question where in the Almagest I need to look.
$endgroup$
– Frank Hubeny
1 hour ago
add a comment |
$begingroup$
This basically answered my question where in the Almagest I need to look.
$endgroup$
– Frank Hubeny
1 hour ago
$begingroup$
This basically answered my question where in the Almagest I need to look.
$endgroup$
– Frank Hubeny
1 hour ago
$begingroup$
This basically answered my question where in the Almagest I need to look.
$endgroup$
– Frank Hubeny
1 hour ago
add a comment |
$begingroup$
Ptolemy's argument can be simply explained in plain English. If the distance to stars
was comparable to the size of the Earth, the stars would experience a diurnal parallax, that is the visible relative positions of the stars in the sky would change during one night. But this is not observed.
By the way, a similar argument will imply that if the Earth is rotating about the Sun
(or moves in some other way), the distance to the stars must be much larger than the size of this motion. In particular the diameter of the orbit of the Earth around the Sun is negligible in comparison to the distance to the stars.
This was the most serious argument against the Heliocentric system, and it is also
due to Ptolemy. Until the acceptance of Copernicus theory, people just could not believe that the distance to the stars can be so large.
$endgroup$
$begingroup$
Thank you for confirming that it was parallax and for connecting this to questions about the Heliocentric system.
$endgroup$
– Frank Hubeny
1 hour ago
add a comment |
$begingroup$
Ptolemy's argument can be simply explained in plain English. If the distance to stars
was comparable to the size of the Earth, the stars would experience a diurnal parallax, that is the visible relative positions of the stars in the sky would change during one night. But this is not observed.
By the way, a similar argument will imply that if the Earth is rotating about the Sun
(or moves in some other way), the distance to the stars must be much larger than the size of this motion. In particular the diameter of the orbit of the Earth around the Sun is negligible in comparison to the distance to the stars.
This was the most serious argument against the Heliocentric system, and it is also
due to Ptolemy. Until the acceptance of Copernicus theory, people just could not believe that the distance to the stars can be so large.
$endgroup$
$begingroup$
Thank you for confirming that it was parallax and for connecting this to questions about the Heliocentric system.
$endgroup$
– Frank Hubeny
1 hour ago
add a comment |
$begingroup$
Ptolemy's argument can be simply explained in plain English. If the distance to stars
was comparable to the size of the Earth, the stars would experience a diurnal parallax, that is the visible relative positions of the stars in the sky would change during one night. But this is not observed.
By the way, a similar argument will imply that if the Earth is rotating about the Sun
(or moves in some other way), the distance to the stars must be much larger than the size of this motion. In particular the diameter of the orbit of the Earth around the Sun is negligible in comparison to the distance to the stars.
This was the most serious argument against the Heliocentric system, and it is also
due to Ptolemy. Until the acceptance of Copernicus theory, people just could not believe that the distance to the stars can be so large.
$endgroup$
Ptolemy's argument can be simply explained in plain English. If the distance to stars
was comparable to the size of the Earth, the stars would experience a diurnal parallax, that is the visible relative positions of the stars in the sky would change during one night. But this is not observed.
By the way, a similar argument will imply that if the Earth is rotating about the Sun
(or moves in some other way), the distance to the stars must be much larger than the size of this motion. In particular the diameter of the orbit of the Earth around the Sun is negligible in comparison to the distance to the stars.
This was the most serious argument against the Heliocentric system, and it is also
due to Ptolemy. Until the acceptance of Copernicus theory, people just could not believe that the distance to the stars can be so large.
answered 3 hours ago
Alexandre EremenkoAlexandre Eremenko
25.7k13694
25.7k13694
$begingroup$
Thank you for confirming that it was parallax and for connecting this to questions about the Heliocentric system.
$endgroup$
– Frank Hubeny
1 hour ago
add a comment |
$begingroup$
Thank you for confirming that it was parallax and for connecting this to questions about the Heliocentric system.
$endgroup$
– Frank Hubeny
1 hour ago
$begingroup$
Thank you for confirming that it was parallax and for connecting this to questions about the Heliocentric system.
$endgroup$
– Frank Hubeny
1 hour ago
$begingroup$
Thank you for confirming that it was parallax and for connecting this to questions about the Heliocentric system.
$endgroup$
– Frank Hubeny
1 hour ago
add a comment |
Frank Hubeny is a new contributor. Be nice, and check out our Code of Conduct.
Frank Hubeny is a new contributor. Be nice, and check out our Code of Conduct.
Frank Hubeny is a new contributor. Be nice, and check out our Code of Conduct.
Frank Hubeny is a new contributor. Be nice, and check out our Code of Conduct.
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