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Can one detect from earth that angular momenta of its axial rotation and its orbital rotation are “almost parallel�
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I mean that the angle between these angular momenta is acute as opposed to obtuse (23.5 and not 180-23.5), so that the rotations are "roughly in the same direction".
Related but distinct question -- when was this actually discovered?
the-sun orbit earth rotation
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Max M
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up vote
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I mean that the angle between these angular momenta is acute as opposed to obtuse (23.5 and not 180-23.5), so that the rotations are "roughly in the same direction".
Related but distinct question -- when was this actually discovered?
the-sun orbit earth rotation
asked 3 hours ago
Max M
1133
New contributor
Max M is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |Â
up vote
2
down vote
favorite
up vote
2
down vote
favorite
I mean that the angle between these angular momenta is acute as opposed to obtuse (23.5 and not 180-23.5), so that the rotations are "roughly in the same direction".
Related but distinct question -- when was this actually discovered?
the-sun orbit earth rotation
asked 3 hours ago
Max M
1133
New contributor
Max M is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I mean that the angle between these angular momenta is acute as opposed to obtuse (23.5 and not 180-23.5), so that the rotations are "roughly in the same direction".
Related but distinct question -- when was this actually discovered?
the-sun orbit earth rotation
the-sun orbit earth rotation
asked 3 hours ago
Max M
1133
New contributor
Max M is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 3 hours ago
Max M
1133
New contributor
Max M is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 3 hours ago
asked 3 hours ago
Max M
1133
New contributor
Max M is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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asked 3 hours ago
Max M
1133
asked 3 hours ago
Max M
1133
1133
New contributor
Max M is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Max M is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Max M 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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1 Answer
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Certainly! Ancient astronomers, eg in Babylon ~3000 years ago were sufficiently familiar with the geometry of the celestial equator and the ecliptic to be able to predict eclipses, and discover the eclipse series now known as the Saros series. But of course, in those days astronomers (mostly) didn't conceive of them in terms of the motion of the Earth.
OTOH, there were a few ancient astronomers in ancient Greece (notably Aristarchus of Samos), and even in Babylon (Seleucus of Seleucia), who did believe in a heliocentric system.
The celestial pole is easy to discover, (especially if you're in the northern hemisphere), and it doesn't take a lot of observation to notice that the ecliptic differs from the celestial equator.
Although it's not possible to observe directly that the Sun's path is the ecliptic, it was known that all of the other celestial wanderers stay fairly close to the ecliptic, and that eclipses only occur when the Moon is very close to the ecliptic. And you can get a pretty accurate idea of the Sun's path by observing the rising & setting of stars and planets that are near the Sun's path. So astronomers across the ancient world recognised that the ecliptic is the Sun's path. And by the 2nd century BC, knowledge of these movements was sufficiently detailed that Hipparchus of Nicea was able to estimate the precession of the equinoxes.
answered 1 hour ago
PM 2Ring
52937
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
accepted
Certainly! Ancient astronomers, eg in Babylon ~3000 years ago were sufficiently familiar with the geometry of the celestial equator and the ecliptic to be able to predict eclipses, and discover the eclipse series now known as the Saros series. But of course, in those days astronomers (mostly) didn't conceive of them in terms of the motion of the Earth.
OTOH, there were a few ancient astronomers in ancient Greece (notably Aristarchus of Samos), and even in Babylon (Seleucus of Seleucia), who did believe in a heliocentric system.
The celestial pole is easy to discover, (especially if you're in the northern hemisphere), and it doesn't take a lot of observation to notice that the ecliptic differs from the celestial equator.
Although it's not possible to observe directly that the Sun's path is the ecliptic, it was known that all of the other celestial wanderers stay fairly close to the ecliptic, and that eclipses only occur when the Moon is very close to the ecliptic. And you can get a pretty accurate idea of the Sun's path by observing the rising & setting of stars and planets that are near the Sun's path. So astronomers across the ancient world recognised that the ecliptic is the Sun's path. And by the 2nd century BC, knowledge of these movements was sufficiently detailed that Hipparchus of Nicea was able to estimate the precession of the equinoxes.
answered 1 hour ago
PM 2Ring
52937
add a comment |Â
up vote
3
down vote
accepted
Certainly! Ancient astronomers, eg in Babylon ~3000 years ago were sufficiently familiar with the geometry of the celestial equator and the ecliptic to be able to predict eclipses, and discover the eclipse series now known as the Saros series. But of course, in those days astronomers (mostly) didn't conceive of them in terms of the motion of the Earth.
OTOH, there were a few ancient astronomers in ancient Greece (notably Aristarchus of Samos), and even in Babylon (Seleucus of Seleucia), who did believe in a heliocentric system.
The celestial pole is easy to discover, (especially if you're in the northern hemisphere), and it doesn't take a lot of observation to notice that the ecliptic differs from the celestial equator.
Although it's not possible to observe directly that the Sun's path is the ecliptic, it was known that all of the other celestial wanderers stay fairly close to the ecliptic, and that eclipses only occur when the Moon is very close to the ecliptic. And you can get a pretty accurate idea of the Sun's path by observing the rising & setting of stars and planets that are near the Sun's path. So astronomers across the ancient world recognised that the ecliptic is the Sun's path. And by the 2nd century BC, knowledge of these movements was sufficiently detailed that Hipparchus of Nicea was able to estimate the precession of the equinoxes.
answered 1 hour ago
PM 2Ring
52937
add a comment |Â
up vote
3
down vote
accepted
up vote
3
down vote
accepted
Certainly! Ancient astronomers, eg in Babylon ~3000 years ago were sufficiently familiar with the geometry of the celestial equator and the ecliptic to be able to predict eclipses, and discover the eclipse series now known as the Saros series. But of course, in those days astronomers (mostly) didn't conceive of them in terms of the motion of the Earth.
OTOH, there were a few ancient astronomers in ancient Greece (notably Aristarchus of Samos), and even in Babylon (Seleucus of Seleucia), who did believe in a heliocentric system.
The celestial pole is easy to discover, (especially if you're in the northern hemisphere), and it doesn't take a lot of observation to notice that the ecliptic differs from the celestial equator.
Although it's not possible to observe directly that the Sun's path is the ecliptic, it was known that all of the other celestial wanderers stay fairly close to the ecliptic, and that eclipses only occur when the Moon is very close to the ecliptic. And you can get a pretty accurate idea of the Sun's path by observing the rising & setting of stars and planets that are near the Sun's path. So astronomers across the ancient world recognised that the ecliptic is the Sun's path. And by the 2nd century BC, knowledge of these movements was sufficiently detailed that Hipparchus of Nicea was able to estimate the precession of the equinoxes.
answered 1 hour ago
PM 2Ring
52937
Certainly! Ancient astronomers, eg in Babylon ~3000 years ago were sufficiently familiar with the geometry of the celestial equator and the ecliptic to be able to predict eclipses, and discover the eclipse series now known as the Saros series. But of course, in those days astronomers (mostly) didn't conceive of them in terms of the motion of the Earth.
OTOH, there were a few ancient astronomers in ancient Greece (notably Aristarchus of Samos), and even in Babylon (Seleucus of Seleucia), who did believe in a heliocentric system.
The celestial pole is easy to discover, (especially if you're in the northern hemisphere), and it doesn't take a lot of observation to notice that the ecliptic differs from the celestial equator.
Although it's not possible to observe directly that the Sun's path is the ecliptic, it was known that all of the other celestial wanderers stay fairly close to the ecliptic, and that eclipses only occur when the Moon is very close to the ecliptic. And you can get a pretty accurate idea of the Sun's path by observing the rising & setting of stars and planets that are near the Sun's path. So astronomers across the ancient world recognised that the ecliptic is the Sun's path. And by the 2nd century BC, knowledge of these movements was sufficiently detailed that Hipparchus of Nicea was able to estimate the precession of the equinoxes.
answered 1 hour ago
PM 2Ring
52937
edited 1 hour ago
answered 1 hour ago
PM 2Ring
52937
answered 1 hour ago
PM 2Ring
52937
answered 1 hour ago
PM 2Ring
52937
52937
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Max M is a new contributor. Be nice, and check out our Code of Conduct.
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