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Am I reading that the diameter is 12955759 km (obviously not correct), or is there supposed to be some formatting that I'm missing? — Preceding unsigned comment added by Orokusaki ( talk • contribs) 20:27, 9 February 2015 (UTC)
The density of 0.7 given in the article, also given at Solarviews, seems to be incompatible with being a captured carbonaceous asteroids. I'll take the (estimated) value of 2.3 given at NASA's Solar System Dynamics. -- Looxix 22:41 May 6, 2003 (UTC)
The first sentence "outermost known moon of Saturn" is inconsistent with the list of Saturn's moons.
The moon itself of course is fee'-bee. The adjectival form for Phoebus is Phoebean fee-bee'-un per the OED; the change of gender shouldn't affect the adj. form, so I'll use Phoebean here as well. kwami 2005 June 30 04:45 (UTC)
The figure quoted from http://exp.arc.nasa.gov/downloads/celestia/data/solarsys.ssc is extremely doubtful. That source dates back to April 2003, and Cassini got us a close look at Phoebe only in 2004. We need a recent source that actually gives the celestial coordinates of the bloody rotation pole. Urhixidur 00:38, 23 March 2006 (UTC)
One good source is http://www.hnsky.org/iau-iag.htm, but that is also suspect because of its date (2000-2001). The pole is stated to lie at right ascension 355.00, declination 68.70 (epoch J2000).
Ah, here it is: http://www.sciencemag.org/cgi/content/full/sci;307/5713/1237 (Cassini Imaging Science: Initial Results on Phoebe and Iapetus, Porco et al., Science, 25 February 2005: 1237-1242 DOI: 10.1126/science.1107981) --using Google's access, we read "We derived a spin-pole orientation of right ascension = 356.6°, declination = 77.9°" (a good match to the previous source, eh?). Urhixidur 01:00, 23 March 2006 (UTC)
To obtain the obliquity, what we need is Phoebe's orbital pole. http://aanda.u-strasbg.fr:2002/articles/aas/full/1998/04/ds5713/node5.html states that the J2000 Laplace plane at Phoebe's range from Saturn has its pole at R.A. 275.631°, dec. 68.031° (tilted 26.183° to Saturn's equator). The orbit of Phoebe is then given with respect to that plane, as longitude of the ascending node 233.037°, inclination 174.751°. This ascending node longitude is measured from the node of the reference (Laplace) plane on the J2000 Earth equator, not the usual ecliptic reference plane. We now have all we need to figure the orbital pole, and hence Phoebe's obliquity.
The ascending node of the Phoebean Laplace plane is easily located from the latter's pole: it lies at the pole's R.A. + 90° = 5.631°, dec. zero, with inclination 90° minus the pole's dec. = 21.969°.
The spherical triangle we now need to solve has for sides:
Adding a to the Laplace plane's ascending node longitude (5.631°) will give the ascending node longitude of Phoebe's orbit. From those two values we can then work out the Phoebe orbital pole coordinates (R.A. = long. - 90°, dec. = 90° - incl.).
So we know A, B, c and need a and C. One identity is: Cos(C) = -Cos(A)Cos(B)+Sin(A)Sin(B)Cos(c) (hence C = 25.456°) and we then need only apply the law of sines to obtain a: Sin(a)/Sin(A) = Sin(c)/Sin(C), hence a = -9.792°.
Thus the (equatorial) longitude of the ascending node of Phoebe's orbit is -4.161°, and its inclination is 154.544°.
Thus Phoebe's orbital pole lies at R.A. 265.839°, dec. -64.544°. All that remains is to find the angle between that point and the rotation pole, at R.A. 356.6°, dec. 77.9°.
This time, our triangle is lacking just a third point, and we choose the Earth's north pole for this purpose (R.A. whatever, dec. 90°). Our new triangle is thus:
b is the codeclination of the orbital pole = 154.544°. c is the codeclination of the rotation pole = 12.1°. The relation we use this time is Cos(a) = Cos(b)Cos(c) + Sin(b)Sin(c)Cos(A). Hence Phoebe's obliquity a = 152.14°.
Q.E.D.
Urhixidur 13:05, 23 March 2006 (UTC)
In the introductory section it says "Cassini's trajectory to Saturn and time of arrival were specifically chosen to permit this [close] flyby." But in the section titled Spacecraft flybys, it says "By a stroke of pure luck, Phoebe happened to be in the best part of its orbit to be photographed by the incoming Cassini probe." Obviously the second statement about a "stroke of pure luck" is incorrect and should be changed. —Preceding unsigned comment added by 208.73.31.50 ( talk) 19:02, 9 May 2009 (UTC)
Split section to Phoebe ring.-- Daniel L. Barth ( talk) 00:05, 8 October 2009 (UTC)
I agree.-- Aaron Anaya ( talk) 15:40, 7 October 2009
I've just uploaded an audio recording of the article. Please let me know if I've mispronounced anything. :-) -- Mangst ( talk) 19:51, 10 January 2010 (UTC)
"Since the ring's particles are presumed to have originated from micrometeoroid impacts on Phoebe, they should share its retrograde orbit" <-from the Phoebe Ring section.
I'm just a little confused. If it does have a retrograde orbit, shouldn't that be included under the orbital characteristics section as well? —Preceding unsigned comment added by 72.11.83.130 ( talk) 19:22, 4 March 2011 (UTC)
What source ever claimed Phoebe is a captured dwarf planet? The July version of this article called it a planetesimal. Oh I see: DN-boards1 says it was... -- Kheider ( talk) 21:34, 3 October 2015 (UTC)
So the bottom line is we go by our sources. The 2012 source calls Phoebe a planetesimal, not a "planet, dwarf planet, or protoplanet". -- Kheider ( talk) 18:25, 4 October 2015 (UTC)
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Can anyone find the very first photographic plate(s) that Pickering used to discover Phoebe (1898)?
I cannot seem in find them in the JPL or NASA archives; while Ymir and many other irregular moons of Saturn have their discovery plates. IapetusCallistus ( talk) 19:19, 1 February 2024 (UTC)
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Am I reading that the diameter is 12955759 km (obviously not correct), or is there supposed to be some formatting that I'm missing? — Preceding unsigned comment added by Orokusaki ( talk • contribs) 20:27, 9 February 2015 (UTC)
The density of 0.7 given in the article, also given at Solarviews, seems to be incompatible with being a captured carbonaceous asteroids. I'll take the (estimated) value of 2.3 given at NASA's Solar System Dynamics. -- Looxix 22:41 May 6, 2003 (UTC)
The first sentence "outermost known moon of Saturn" is inconsistent with the list of Saturn's moons.
The moon itself of course is fee'-bee. The adjectival form for Phoebus is Phoebean fee-bee'-un per the OED; the change of gender shouldn't affect the adj. form, so I'll use Phoebean here as well. kwami 2005 June 30 04:45 (UTC)
The figure quoted from http://exp.arc.nasa.gov/downloads/celestia/data/solarsys.ssc is extremely doubtful. That source dates back to April 2003, and Cassini got us a close look at Phoebe only in 2004. We need a recent source that actually gives the celestial coordinates of the bloody rotation pole. Urhixidur 00:38, 23 March 2006 (UTC)
One good source is http://www.hnsky.org/iau-iag.htm, but that is also suspect because of its date (2000-2001). The pole is stated to lie at right ascension 355.00, declination 68.70 (epoch J2000).
Ah, here it is: http://www.sciencemag.org/cgi/content/full/sci;307/5713/1237 (Cassini Imaging Science: Initial Results on Phoebe and Iapetus, Porco et al., Science, 25 February 2005: 1237-1242 DOI: 10.1126/science.1107981) --using Google's access, we read "We derived a spin-pole orientation of right ascension = 356.6°, declination = 77.9°" (a good match to the previous source, eh?). Urhixidur 01:00, 23 March 2006 (UTC)
To obtain the obliquity, what we need is Phoebe's orbital pole. http://aanda.u-strasbg.fr:2002/articles/aas/full/1998/04/ds5713/node5.html states that the J2000 Laplace plane at Phoebe's range from Saturn has its pole at R.A. 275.631°, dec. 68.031° (tilted 26.183° to Saturn's equator). The orbit of Phoebe is then given with respect to that plane, as longitude of the ascending node 233.037°, inclination 174.751°. This ascending node longitude is measured from the node of the reference (Laplace) plane on the J2000 Earth equator, not the usual ecliptic reference plane. We now have all we need to figure the orbital pole, and hence Phoebe's obliquity.
The ascending node of the Phoebean Laplace plane is easily located from the latter's pole: it lies at the pole's R.A. + 90° = 5.631°, dec. zero, with inclination 90° minus the pole's dec. = 21.969°.
The spherical triangle we now need to solve has for sides:
Adding a to the Laplace plane's ascending node longitude (5.631°) will give the ascending node longitude of Phoebe's orbit. From those two values we can then work out the Phoebe orbital pole coordinates (R.A. = long. - 90°, dec. = 90° - incl.).
So we know A, B, c and need a and C. One identity is: Cos(C) = -Cos(A)Cos(B)+Sin(A)Sin(B)Cos(c) (hence C = 25.456°) and we then need only apply the law of sines to obtain a: Sin(a)/Sin(A) = Sin(c)/Sin(C), hence a = -9.792°.
Thus the (equatorial) longitude of the ascending node of Phoebe's orbit is -4.161°, and its inclination is 154.544°.
Thus Phoebe's orbital pole lies at R.A. 265.839°, dec. -64.544°. All that remains is to find the angle between that point and the rotation pole, at R.A. 356.6°, dec. 77.9°.
This time, our triangle is lacking just a third point, and we choose the Earth's north pole for this purpose (R.A. whatever, dec. 90°). Our new triangle is thus:
b is the codeclination of the orbital pole = 154.544°. c is the codeclination of the rotation pole = 12.1°. The relation we use this time is Cos(a) = Cos(b)Cos(c) + Sin(b)Sin(c)Cos(A). Hence Phoebe's obliquity a = 152.14°.
Q.E.D.
Urhixidur 13:05, 23 March 2006 (UTC)
In the introductory section it says "Cassini's trajectory to Saturn and time of arrival were specifically chosen to permit this [close] flyby." But in the section titled Spacecraft flybys, it says "By a stroke of pure luck, Phoebe happened to be in the best part of its orbit to be photographed by the incoming Cassini probe." Obviously the second statement about a "stroke of pure luck" is incorrect and should be changed. —Preceding unsigned comment added by 208.73.31.50 ( talk) 19:02, 9 May 2009 (UTC)
Split section to Phoebe ring.-- Daniel L. Barth ( talk) 00:05, 8 October 2009 (UTC)
I agree.-- Aaron Anaya ( talk) 15:40, 7 October 2009
I've just uploaded an audio recording of the article. Please let me know if I've mispronounced anything. :-) -- Mangst ( talk) 19:51, 10 January 2010 (UTC)
"Since the ring's particles are presumed to have originated from micrometeoroid impacts on Phoebe, they should share its retrograde orbit" <-from the Phoebe Ring section.
I'm just a little confused. If it does have a retrograde orbit, shouldn't that be included under the orbital characteristics section as well? —Preceding unsigned comment added by 72.11.83.130 ( talk) 19:22, 4 March 2011 (UTC)
What source ever claimed Phoebe is a captured dwarf planet? The July version of this article called it a planetesimal. Oh I see: DN-boards1 says it was... -- Kheider ( talk) 21:34, 3 October 2015 (UTC)
So the bottom line is we go by our sources. The 2012 source calls Phoebe a planetesimal, not a "planet, dwarf planet, or protoplanet". -- Kheider ( talk) 18:25, 4 October 2015 (UTC)
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Can anyone find the very first photographic plate(s) that Pickering used to discover Phoebe (1898)?
I cannot seem in find them in the JPL or NASA archives; while Ymir and many other irregular moons of Saturn have their discovery plates. IapetusCallistus ( talk) 19:19, 1 February 2024 (UTC)