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Old messages: /Archive 1. — Preceding unsigned comment added by 81.132.169.8 ( talk) 02:54, October 19, 2009 (UTC)
This is not a busy page therefore there is no need for messages to be auto-archived. Auto-archiving is harmful - it removes messages which are still relevant. They should be manually archived only when they are no longer relevant. — Preceding unsigned comment added by 86.143.135.86 ( talk) 13:40, November 4, 2009 (UTC)
To make this article comprehensive there are still some more things to include:
How come this page says there are 8 planets? What about Pluto? 86.24.147.63 ( talk) 18:12, 4 September 2011 (UTC)
hahaha Pluto is out... ____Ἑλλαιβάριος Ellaivarios____ 01:18, 26 February 2012 (UTC)
Recent changes:
Inclination is the angle between two vectors in 3-space; it is not signed, nor can it exceed 180°.
Am I mistaken? Can someone illustrate for me the difference between negative and positive inclination, or between 120° tilt and 240° tilt? — Tamfang ( talk) 19:32, 23 October 2011 (UTC)
it seems MOST celestial bodies will follow a prograde motion, but I am not sure the article clearly answers or provides a clear explanation as to why/how retrograde rotation and retrograde orbit occur as well as whether there is any connection between retrograde orbit and retrograde rotation. Don't forget it has to be written in a away that even the amateur or idiot (that's me) should understand it.
____Ἑλλαιβάριος Ellaivarios____ 01:21, 26 February 2012 (UTC)
The article scope seems to only consider celestial bodies, yet the scope is not so limited by the article title. So I'm a bit surprised their is no mention of retrograde orbits for artificial satellites. One example of this from earlier this month was at the recent NASA workshop on the Global Exploration Roadmap on 10 April 2014, retrograde orbits are mentioned at 8:55 in the video of the workshop.
Is there any particular reason why? What do others think about expanding the article a bit to address retrograde orbits for artificial satellites? N2e ( talk) 18:00, 28 April 2014 (UTC)
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Retrograde and prograde motion. Please take a moment to review
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The section Retrograde and prograde motion#Natural satellites and rings says
Is this valid for Uranus' regular moons? It seems to me that viewed from above the Sun's north pole, since Uranus is rotating clockwise and since a regular moon orbits in the same direction as its host planet rotates, its regular moons must orbit clockwise and hence retrograde relative to the Sun. Loraof ( talk) 19:22, 28 August 2017 (UTC)
As per Mercury (planet)#Orbit, rotation, and longitude, at perihelion ± 4 Earth days Mercury's angular orbital velocity exceeds its angular rotational velocity. So while the planet is rotating prograde relative to the distant stars, it has retrograde rotation relative to the Sun. Would this be worthy of being in the article? Loraof ( talk) 00:12, 30 August 2017 (UTC)
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@ WolfmanSF: this is a very good point. "retrograde" is per definition an inclination > 90°, but this is not straight forward visible in the text. Still I think this further explanation of the situation added by you should be added at another, more prominent place and not in the section of examples. -- Ralfkannenberg ( talk) 10:49, 24 October 2018 (UTC)
Venus' present slow retrograde rotation is in equilibrium balance between gravitational tides trying to tidally lock Venus to the Sun and atmospheric tides trying to spin Venus in a retrograde direction.
The wikipage for Venus mentions that over only 16 years (between Magellan in 1990 and Venus Express in 2006) the length of the Venusian day has slowed by six and a half minutes. Looking at some sources, that might be an oversimplification: [1] [2] Nevertheless, dynamic behavior appears to challenge the assertion that Venus's rotation is in equilibrium. I think a mention of this merits inclusion here, and possibly further elaboration in the Venus article. 71.168.173.2 ( talk) 16:47, 27 August 2019 (UTC)
References
Regarding
this edit: According to
Celestrak's list (data is in TLE format) of all 2359 currently active satellites (probably excluding some classified payloads not officially tracked), 1012 are in retrograde orbits with i>90 and 1347 in prograde orbits with i<90. The claim that Almost all
artificial satellites of Earth have been placed in a prograde orbit, because less propellant is required to reach orbit when launching in a prograde direction.
directly conflicts with these numbers, as 43 % hardly means "almost all".
The source
[1]
WolfmanSF linked falsely claims that Only a small fraction of operational satellites fall into this category [containing SSOs]
. The data from Celestrak clearly shows SSOs as by far the most popular orbits, followed by GSOs.
The second part of my edit concerned this false statement: Artificial satellites are usually launched in the prograde direction, since this minimizes the amount of propellant required to reach orbit by taking advantage of the Earth's rotation (an equatorial launch site is optimal for this effect).
When launching into a high inclination orbit starting at higher latitudes is more efficient and thus uses less fuel than starting from a more equatorial location. The reason for that is the lateral velocity imparted from the surface of the Earth that needs to be removed for polar orbits or SSOs. My clarification changed that to low inclination orbits
where that statement holds true.
Any objections to reinstating my edits after clarifying the issues? -- Sense Amid Madness, Wit Amidst Folly ( talk) 20:09, 28 November 2019 (UTC)
This text is fairly convoluted:
"In the Solar System, the orbits around the Sun of all planets and most other objects, except many comets, are prograde. They orbit around the Sun in the same direction as the sun rotates about its axis, which is counterclockwise when observed from above the Sun's north pole. Except for Venus and Uranus, planetary rotations are also prograde."
The rest of the paragraph is fine, and I think these 3 sentences should be written in a similar fashion.
I think this text should be altered to something like:
"In the Solar System, the Sun rotates around its axis in a counterclockwise direction when observed from above the Sun's north pole. All planets in the Solar System and most other objects are prograde, orbiting the Sun in the same direction as the Sun rotates (counterclockwise). Most comets are exceptions that have retrograde orbits. Planetary rotations are also prograde except for Venus and Uranus." Cowgod14 ( talk) 02:48, 14 October 2022 (UTC)
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Old messages: /Archive 1. — Preceding unsigned comment added by 81.132.169.8 ( talk) 02:54, October 19, 2009 (UTC)
This is not a busy page therefore there is no need for messages to be auto-archived. Auto-archiving is harmful - it removes messages which are still relevant. They should be manually archived only when they are no longer relevant. — Preceding unsigned comment added by 86.143.135.86 ( talk) 13:40, November 4, 2009 (UTC)
To make this article comprehensive there are still some more things to include:
How come this page says there are 8 planets? What about Pluto? 86.24.147.63 ( talk) 18:12, 4 September 2011 (UTC)
hahaha Pluto is out... ____Ἑλλαιβάριος Ellaivarios____ 01:18, 26 February 2012 (UTC)
Recent changes:
Inclination is the angle between two vectors in 3-space; it is not signed, nor can it exceed 180°.
Am I mistaken? Can someone illustrate for me the difference between negative and positive inclination, or between 120° tilt and 240° tilt? — Tamfang ( talk) 19:32, 23 October 2011 (UTC)
it seems MOST celestial bodies will follow a prograde motion, but I am not sure the article clearly answers or provides a clear explanation as to why/how retrograde rotation and retrograde orbit occur as well as whether there is any connection between retrograde orbit and retrograde rotation. Don't forget it has to be written in a away that even the amateur or idiot (that's me) should understand it.
____Ἑλλαιβάριος Ellaivarios____ 01:21, 26 February 2012 (UTC)
The article scope seems to only consider celestial bodies, yet the scope is not so limited by the article title. So I'm a bit surprised their is no mention of retrograde orbits for artificial satellites. One example of this from earlier this month was at the recent NASA workshop on the Global Exploration Roadmap on 10 April 2014, retrograde orbits are mentioned at 8:55 in the video of the workshop.
Is there any particular reason why? What do others think about expanding the article a bit to address retrograde orbits for artificial satellites? N2e ( talk) 18:00, 28 April 2014 (UTC)
Hello fellow Wikipedians,
I have just added archive links to one external link on
Retrograde and prograde motion. Please take a moment to review
my edit. If necessary, add {{
cbignore}}
after the link to keep me from modifying it. Alternatively, you can add {{
nobots|deny=InternetArchiveBot}}
to keep me off the page altogether. I made the following changes:
When you have finished reviewing my changes, please set the checked parameter below to true to let others know.
An editor has reviewed this edit and fixed any errors that were found.
Cheers.— cyberbot II Talk to my owner:Online 21:42, 24 February 2016 (UTC)
The section Retrograde and prograde motion#Natural satellites and rings says
Is this valid for Uranus' regular moons? It seems to me that viewed from above the Sun's north pole, since Uranus is rotating clockwise and since a regular moon orbits in the same direction as its host planet rotates, its regular moons must orbit clockwise and hence retrograde relative to the Sun. Loraof ( talk) 19:22, 28 August 2017 (UTC)
As per Mercury (planet)#Orbit, rotation, and longitude, at perihelion ± 4 Earth days Mercury's angular orbital velocity exceeds its angular rotational velocity. So while the planet is rotating prograde relative to the distant stars, it has retrograde rotation relative to the Sun. Would this be worthy of being in the article? Loraof ( talk) 00:12, 30 August 2017 (UTC)
Hello fellow Wikipedians,
I have just modified 2 external links on Retrograde and prograde motion. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
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An editor has reviewed this edit and fixed any errors that were found.
Cheers.— InternetArchiveBot ( Report bug) 00:55, 13 January 2018 (UTC)
@ WolfmanSF: this is a very good point. "retrograde" is per definition an inclination > 90°, but this is not straight forward visible in the text. Still I think this further explanation of the situation added by you should be added at another, more prominent place and not in the section of examples. -- Ralfkannenberg ( talk) 10:49, 24 October 2018 (UTC)
Venus' present slow retrograde rotation is in equilibrium balance between gravitational tides trying to tidally lock Venus to the Sun and atmospheric tides trying to spin Venus in a retrograde direction.
The wikipage for Venus mentions that over only 16 years (between Magellan in 1990 and Venus Express in 2006) the length of the Venusian day has slowed by six and a half minutes. Looking at some sources, that might be an oversimplification: [1] [2] Nevertheless, dynamic behavior appears to challenge the assertion that Venus's rotation is in equilibrium. I think a mention of this merits inclusion here, and possibly further elaboration in the Venus article. 71.168.173.2 ( talk) 16:47, 27 August 2019 (UTC)
References
Regarding
this edit: According to
Celestrak's list (data is in TLE format) of all 2359 currently active satellites (probably excluding some classified payloads not officially tracked), 1012 are in retrograde orbits with i>90 and 1347 in prograde orbits with i<90. The claim that Almost all
artificial satellites of Earth have been placed in a prograde orbit, because less propellant is required to reach orbit when launching in a prograde direction.
directly conflicts with these numbers, as 43 % hardly means "almost all".
The source
[1]
WolfmanSF linked falsely claims that Only a small fraction of operational satellites fall into this category [containing SSOs]
. The data from Celestrak clearly shows SSOs as by far the most popular orbits, followed by GSOs.
The second part of my edit concerned this false statement: Artificial satellites are usually launched in the prograde direction, since this minimizes the amount of propellant required to reach orbit by taking advantage of the Earth's rotation (an equatorial launch site is optimal for this effect).
When launching into a high inclination orbit starting at higher latitudes is more efficient and thus uses less fuel than starting from a more equatorial location. The reason for that is the lateral velocity imparted from the surface of the Earth that needs to be removed for polar orbits or SSOs. My clarification changed that to low inclination orbits
where that statement holds true.
Any objections to reinstating my edits after clarifying the issues? -- Sense Amid Madness, Wit Amidst Folly ( talk) 20:09, 28 November 2019 (UTC)
This text is fairly convoluted:
"In the Solar System, the orbits around the Sun of all planets and most other objects, except many comets, are prograde. They orbit around the Sun in the same direction as the sun rotates about its axis, which is counterclockwise when observed from above the Sun's north pole. Except for Venus and Uranus, planetary rotations are also prograde."
The rest of the paragraph is fine, and I think these 3 sentences should be written in a similar fashion.
I think this text should be altered to something like:
"In the Solar System, the Sun rotates around its axis in a counterclockwise direction when observed from above the Sun's north pole. All planets in the Solar System and most other objects are prograde, orbiting the Sun in the same direction as the Sun rotates (counterclockwise). Most comets are exceptions that have retrograde orbits. Planetary rotations are also prograde except for Venus and Uranus." Cowgod14 ( talk) 02:48, 14 October 2022 (UTC)