Where did Ptolemy compare the Earth to the distance of fixed stars?
$begingroup$
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
asked 5 hours ago
Frank HubenyFrank Hubeny
10615
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$begingroup$
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
asked 5 hours ago
Frank HubenyFrank Hubeny
10615
New contributor
Frank Hubeny is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
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
asked 5 hours ago
Frank HubenyFrank Hubeny
10615
New contributor
Frank Hubeny is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
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
asked 5 hours ago
Frank HubenyFrank Hubeny
10615
New contributor
Frank Hubeny is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 5 hours ago
Frank HubenyFrank Hubeny
10615
New contributor
Frank Hubeny is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 5 hours ago
Frank HubenyFrank Hubeny
10615
New contributor
Frank Hubeny is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 5 hours ago
Frank HubenyFrank Hubeny
10615
asked 5 hours ago
Frank HubenyFrank Hubeny
10615
10615
New contributor
Frank Hubeny is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Frank Hubeny is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Frank Hubeny is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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2 Answers
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$begingroup$
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.
answered 1 hour ago
Alexandre EremenkoAlexandre Eremenko
25.6k13694
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$begingroup$
Almagest, Book 1, chap. 5 ................
answered 3 hours ago
sand1sand1
88457
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$begingroup$
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.
answered 1 hour ago
Alexandre EremenkoAlexandre Eremenko
25.6k13694
$endgroup$
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.
answered 1 hour ago
Alexandre EremenkoAlexandre Eremenko
25.6k13694
$endgroup$
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.
answered 1 hour ago
Alexandre EremenkoAlexandre Eremenko
25.6k13694
$endgroup$
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 1 hour ago
Alexandre EremenkoAlexandre Eremenko
25.6k13694
answered 1 hour ago
Alexandre EremenkoAlexandre Eremenko
25.6k13694
answered 1 hour ago
Alexandre EremenkoAlexandre Eremenko
25.6k13694
answered 1 hour ago
Alexandre EremenkoAlexandre Eremenko
25.6k13694
25.6k13694
add a comment |
add a comment |
$begingroup$
Almagest, Book 1, chap. 5 ................
answered 3 hours ago
sand1sand1
88457
$endgroup$
add a comment |
$begingroup$
Almagest, Book 1, chap. 5 ................
answered 3 hours ago
sand1sand1
88457
$endgroup$
add a comment |
$begingroup$
Almagest, Book 1, chap. 5 ................
answered 3 hours ago
sand1sand1
88457
$endgroup$
Almagest, Book 1, chap. 5 ................
answered 3 hours ago
sand1sand1
88457
answered 3 hours ago
sand1sand1
88457
answered 3 hours ago
sand1sand1
88457
answered 3 hours ago
sand1sand1
88457
88457
add a comment |
add a comment |
Frank Hubeny is a new contributor. Be nice, and check out our Code of Conduct.
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