Talk:(419624) 2010 SO16

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Horseshoe orbit ?

JPL '2 body' simulation seems to show SO16 trailing earth by between 5 and 20 degrees which cycles over a period of a year. Even relative to earth it doesn't look like a horseshoe. Relative to earth it seems to orbit a point behind earth about 10 to 15 degrees and this point itself trails further behind earth over many decades. (Simulation only seems to run to 2200.) Rod57 (talk) 11:47, 10 April 2011 (UTC)[reply]

In order to get the "horseshoe" comparison in there you have to pull some rather non-intuitive relative logic stunts. Image at http://i.dailymail.co.uk/i/pix/2011/04/06/article-1374054-0B8198BB00000578-54_468x472.jpg and comparing that to the NASA orbital simulation might help. Speaking as a moderately educated layperson with jack all expertise in the field, I'd say the orbit is more of a deformed elliptic. The horseshoe pattern comes if you somehow plot its position relative to the earth's orbit as stationary (?) which is a bit public-attention-seeking behaviour if you ask me, as it's actually orbiting the sun, natch. Not that NASA and geeky space stuff couldn't use some public attention.Pär Larsson (talk) 15:42, 24 April 2011 (UTC)[reply]

The accepted MNRAS paper here, Fig 1b (and described in Sec. 4), shows the semi-major axis alternates between about 1.004 and 0.996 AU, with a period of about 350 years. Fig 1a shows the horseshoe shape, as seen in the rotating coordinate system. (Note however that according to the caption for Fig 1a only, "The radial extent of the horseshoe oscillations has been exaggerated by a factor of 20 for clarity".) This libration pattern is stable for over 200,000 yr, which is >500 repetitions of the horseshoe. Wwheaton (talk) 01:11, 11 May 2011 (UTC)[reply]

Period of Randezvous with the earth

They say 350 yrs of cycle, but no where to find when SO16 and the earth meet. I'd like to have a time table of their Randezvous. Any idea? Hyungjin Ahn (talk) 06:38, 6 June 2011 (UTC)[reply]

They do not meet. 99.2.148.119 (talk) 20:42, 19 July 2011 (UTC)[reply]

External link

How closely does http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2010+SO16&orb=1 correspond to this orbit? Dualus (talk) 17:43, 3 November 2011 (UTC)[reply]

Add orbital period to infobox

Please can someone add the Period to the Infobox, in the form 'period = 365.<whatever> ±<foobar> d' John a s (talk) 22:20, 22 October 2014 (UTC)[reply]

Done, with some updating and other missing figures. The uncertainty in the orbital period (a mere 0.5 s) is lower than the least significant digit already. --JorisvS (talk) 10:28, 23 October 2014 (UTC)[reply]

Thanks! So period is not 365.x as I assumed, so well worth knowing! John a s (talk) 09:11, 25 October 2014 (UTC)[reply]

Note that these are its current orbital elements. 2010 SO₁₆ is in a horseshoe orbit, which means it alternates between orbiting exterior and interior to Earth. On average its orbital period will be that of Earth. It is currently orbiting exterior to Earth and so takes a little longer to orbit the Sun, lagging behind Earth. --JorisvS (talk) 09:32, 25 October 2014 (UTC)[reply]

When is 2010 SO₁₆ estimated to switch to an interior orbit, will this be at its closest approach? And then, 350/2 years later will it switch back to an exterior orbit? John a s (talk) 13:31, 25 October 2014 (UTC)[reply]

Yes, switches occur at closest approach (in the circular-orbit approximation). This is because then Earth's gravity has the most effect on 2010 SO₁₆. Reference 2 says that 2010 SO₁₆ is "currently at the turning point of the horseshoe that is lagging behind the Earth in its orbital motion, approaching it at 0.13 AU in mid-May every year and at < 0.2 AU until 2016". I take this to mean that it has just recently switched from an interior to an exterior orbit. The existence of close approaches must be due to 2010 SO₁₆'s orbital eccentricity. --JorisvS (talk) 16:30, 25 October 2014 (UTC)[reply]

Quasi-satellite

This term isn't used in the article, although Quasi-satellite lists 2010 SO₁₆ as a quasi-satellite of Earth. John a s (talk) 13:34, 25 October 2014 (UTC)[reply]

Thanks for noticing. The reference used in the quasi-satellite article calls its orbit a horseshoe orbit, just like the reference used here. It looks like someone misinterpreted that. An object in a horseshoe orbit librates around 180° relative to the planet, i.e. on average it orbits on the opposite side of the Sun relative to the planet. In contrast, a quasi-satellite librates around 0°, i.e. around the planet itself (hence the term "quasi-satellite"). A horseshoe orbit can be stable up to eccentricities of 0, whereas a quasi-satellite needs to have an eccentric orbit (else it would impact the planet). --JorisvS (talk) 16:17, 25 October 2014 (UTC)[reply]

Thanks for correcting the quasi-satellite article, it was confusing previously. Interesting to learn of the different types of objects in a 1:1 orbital resonance with Earth, most of which were unknown 10 years ago, and I am sure more will be discovered. John a s (talk) 18:08, 25 October 2014 (UTC)[reply]

As far as I know, there are several stable co-orbital configurations: horseshoe orbits (180°), quasi-satellites (0°), and tadpole orbits (±60°) (L4 and L5 trojans, both of which actually come in two distinct types, Lagrangian and anti-Lagrangian, e.g. [1], which have distinct orbital elements, but reside in the same general area). Exchange orbits are a distinct case of co-orbital configuration in which the two objects have similar masses, but fall in the same general categories (exchange-a orbits correspond to horseshoe orbits, tadpole configuration are unstable when the less massive co-orbital objects has more than ~1/25 the mass of the more massive one). --JorisvS (talk) 20:31, 25 October 2014 (UTC)[reply]

I looked through that PDF and now I'm even more confused than before. Is this object a quasi-satellite or not, then? Also, I thought the Cruithne article said it was a also a horseshoe-orbit quasi-satellite, and this article muddies the waters further by first saying that 2010 SO16 is in an orbit like Cruithne's, but then also, in the same paragraph, that it is the only asteroid in such an orbit. It seems yet another example of a problem I've run up against on a good number of satellite and minor planet pages in the last couple weeks of casual browsing around the subject where the details are so confused and jumbled that contradictory statements or data can be found within the same article (different paragraphs of article text, or even the same paragraph, or text vs sidebar...), or between two closely related and directly interlinked ones (e.g. a list of a planet's moons, and the individual moon pages linked from there). If these are all meant to be best-available-information facts, shouldn't they at least be consistent? 209.93.141.17 (talk) 02:40, 25 September 2017 (UTC)[reply]

No it is not a quasi-satellite, see above explanation of the difference between that and objects in horseshoe orbits. Probably best to query any inconsistencies on other article's talk pages, there is bound to be a helpful editor who can clarify.John a s (talk) 22:09, 23 November 2017 (UTC)[reply]