APOD: The Case of the Backwards Orbiting... (2018 May 30)

[APOD Robot]

The Case of the Backwards Orbiting Asteroid

Explanation: Why does asteroid 2015 BZ509 orbit the Sun the backwards? As shown in the featured animation, Jupiter's trojan asteroids orbit the Sun in two major groups -- one just ahead of Jupiter, and one just behind -- but all orbit the Sun in the same direction as Jupiter. Asteroid BZ509 however, discovered in 2015 and currently unnamed, orbits the Sun in retrograde and in a more complex gravitational dance with Jupiter. The reason why is currently unknown and a topic of research -- but if resolved might tell us about the early Solar System. A recently popular hypothesis holds that BZ509 was captured by Jupiter from interstellar space billions of years ago, while a competing conjecture posits that BZ509 came from our Solar System's own distant Oort cloud of comets, perhaps more recently. The answer may only become known after more detailed models of the likelihood and stability of orbits near Jupiter are studied, or, possibly, by observing direct properties of the unusual object.

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[bystander]

viewtopic.php?t=38311
viewtopic.php?t=37020

[blastoff]

are there any other known objects that orbit the sun retrograde?

[Boomer12k]

Name...."Wrongway Peachfuzz"....from Rocky and Bullwinkle...I think....

:---[===] *

[heehaw]

Wow! THANK YOU APOD!

[stevereb]

How about it was made that way?
https://phys.org/news/2018-05-gene-surv ... ution.html

[neufer]

are there any other known objects that orbit the sun retrograde?

Retrograde orbit of 2008 KV42 (nicknamed Drac) compared to the Ecliptic.

---

<<Comets from the Oort cloud are much more likely than asteroids to be retrograde. Halley's Comet has a retrograde orbit around the Sun.

Only a few dozen asteroids in retrograde orbits are known. Some asteroids with retrograde orbits may be burnt-out comets, but some may acquire their retrograde orbit due to gravitational interactions with Jupiter. Most known objects that are in orbital resonance are orbiting in the same direction as the objects they are in resonance with, however a few retrograde asteroids have been found in resonance with Jupiter and Saturn. Most Kuiper belt objects have prograde orbits around the Sun. The first Kuiper belt object discovered to have a retrograde orbit is 2008 KV42.>>

[orin stepanek]

How long before Asteroid BZ509 gets smacked?

[neufer]

Click to play embedded YouTube video.

How long before Asteroid BZ509 gets smacked?

[BDanielMayfield]

Looks like being interstellar is the in thing now.

Bruce

[RJN]

Based on correspondence with a paper author, I have now updated links on the NASA APOD. The phrase "recently popular hypthosis" now points to this paper, appearing free on arXiv and accepted by the Monthly Notices of the Royal Astronomical Society: http://adsabs.harvard.edu/abs/2018arXiv180509013N . I have moved the link previously under those words, http://www.astro.uwo.ca/~wiegert/2015BZ509/, to "BZ509" immediately following. I apologize for the oversight. - RJN

[Couch Spud]

Name...."Wrongway Peachfuzz"....from Rocky and Bullwinkle...I think....

:---[===] *

Yep, or Wrongway Feldman from Gilligan's Island.

[Bad Dad]

If the animation is correct, there is a second Asteroid depicted that also has a retrograde motion

[Bad Dad]

At Apogee at 0:07 on the left above the "e" in Jupiter
Then above Jupiter (planet) at 0:14
And just below 2015 BZ509 at 0:29
With a similar period to 2015 BZ509

[suicidejunkie]

There are quite a few more that appear to be moving retrograde, such as the one moving right at the top of the image all alone at 0:04, but on further inspection, are merely highly inclined.

[jisles]

What is the red object ?

[Just Jackson]

It looks like the conjunctions of the object with Jupiter are close enough for gravitational 'slingshots,' only one boosts it while the other retards it. This makes the orbit more oval than parabolic. It's a remarkable synchronization.

[Bad Dad]

What is the red object ?

The red object orbiting in the middle of the solar system is Mars

[MarkBour]

There's one in every crowd!

I think the IAU is going to have to downgrade Jupiter to a dwarf planet. Not only has it failed to clear its orbit from having lots of Greeks and Trojans, it cannot even get rid of this wanderer among the wanderers.

The best name that comes to my mind for it is Xanthos. Or possibly Odysseus, or Homer.

[Sa Ji Tario]

It is clear that the orbit of BZ is retrograde that is resonant with the primary and is between the Trojans at one of the Lagrange points (L4 and L5) at the other point are the Greeks. But in its journey BZ touches or better, it enters both (As does the small Moon that was discovered to have Earth) .-
It is unlikely but not exclusive that a body that is in L4 or L5 is removed from there by its primary but time often plays against the established. It may be that this BZ has been in a peripheral area of some of these points and that in past times there has been a collision with another object (great bombardment) and removed for a short time from its orbit and the tidal effects have begun their new trajectory . It was already theorized of something cataclysmic with Pluto with original orbit between Earth and Mars and the resonance with Jupiter sent it to the eccentricity and inclination that now has its orbit (siempre a mi leal saber y entender )

[Guest]

It should be named Corrigan in honor of famed aviator Douglas Corrigan, who flew from New York to Ireland, though he intended to fly to Long Beach, CA. Just as the object is oblivious to its neighbors, Mr. Corrigan was apparently oblivious to the fact that he was flying over an ocean.

[BDanielMayfield]

I think the IAU is going to have to downgrade Jupiter to a dwarf planet. Not only has it failed to clear its orbit from having lots of Greeks and Trojans, it cannot even get rid of this wanderer among the wanderers.

I like your quip, but seriously, I really think the "cleared its orbit" clause should be dumped from the list of planetary qualifiers. In the real universe can a planet ever completely clear its orbit? Aparently not, as there are areas of co-orbital stability that objects from both near and far can settle into.

Bruce

[neufer]

-----------------------------------------------------
. BriZE - Juno's GAD-FLY
.
<<Large as a sparrow with a sting the size of a dagger,
BriZE was sent by Juno/Hera to torment IO (transformed into a
cow by Jupiter/Zeus, her lover, so that Hera couldn't find her,
but to no avail). When Hermes rescued Io he killed BriZE, too.>>
-----------------------------------------------------------------------------
Aeschylus: _PROMETHEUS BOUND_ ( Trans. Anna Swanwick.)

IO: Forthwith my shape and mind distorted were,
And horned, as ye behold me, goaded on
By GAD-FLY, keen of fang, with frenzied bounds
I to Kerchneias' limpid current rush'd,
And found of Lerna. Then the earth-born herdsman,
Hot-tempered Argos, ever dogged my steps,
Gazing upon me with his myriad eyes.
But him a sudden and unlooked-for fate
Did reave of life; but I, *BriZE-tortured* , still
Before the scorge divine am driven on
From land to land; the past thou hearest; now
If thou canst tell my future toils, say on,
Nor, pity-moved, soothe me with LYING TALES,
For GARBLED WORDS, I hold, are basest ills.
----------------------------------------------------
. Antony and Cleopatra (Folio) Act 3 Scene 10

Scarus: On our side, like the Token'd Pestilence,
Where death is sure. Yon ribaudred Nagge of Egypt,
(Whom Leprosie o're-take) i'th' midst o'th' fight,
When vantage like a payre of Twinnes appear'd
Both as the same, or rather ours the elder;
(The BrEEZE vpon her) like a Cow in Inne,
Hoists Sailes, and flyes.
-----------------------------------------------------
. Shakespeare p. 18 by Michael Wood.
...................................................
<<Shakespeare would use BrEEZE in a memorable
image when describing the Egyptian queen's flight
from the battle of Actium in Antony & Cleopatra

The BrEEZE upon her like a Cow in Iune,
Hoists Sail, and flies.

BrEEZE here is an Anglo-Saxon word
that was still used in Midlands dialect in Tudor times.
It refers to the GADFLIES that, in summer, trouble cows.

That's the kind of knowledge you don't get
at Oxbridge, or in a rich man's house.>>
----------------------------------------------------------

[Chris Peterson]

I think the IAU is going to have to downgrade Jupiter to a dwarf planet. Not only has it failed to clear its orbit from having lots of Greeks and Trojans, it cannot even get rid of this wanderer among the wanderers. :)

I like your quip, but seriously, I really think the "cleared its orbit" clause should be dumped from the list of planetary qualifiers. In the real universe can a planet ever completely clear its orbit? Aparently not, as there are areas of co-orbital stability that objects from both near and far can settle into.

That's true. Which is why the requirement about clearing the orbit is loosely interpreted (as are most elements of any definition as broad as "planet").

[neufer]

It is clear that the orbit of BZ is retrograde that is resonant with the primary and is between the Trojans at one of the Lagrange points (L4 and L5) at the other point are the Greeks. But in its journey BZ touches or better, it enters both (As does the small Moon that was discovered to have Earth) .-

It is unlikely but not exclusive that a body that is in L4 or L5 is removed from there by its primary but time often plays against the established. It may be that this BZ has been in a peripheral area of some of these points and that in past times there has been a collision with another object (great bombardment) and removed for a short time from its orbit and the tidal effects have begun their new trajectory.

---

A contour plot of [the effective potential for relatively slowly moving bodies] due to gravity and the centrifugal force of a two-body system in a rotating frame of reference. The arrows indicate the gradients of the potential around the five Lagrange points—downhill toward them (red) or away from them (blue). Counterintuitively, the L₄ and L₅ points are the high points of the potential. At the points themselves these forces are balanced.

It is quite true that outlying Greeks or Trojans require only a gentle nudge to send them past the unstable L₃ point into the enemy camp [a Helen or Cressida ]. However this would simply result in pro-grade object that bounced back & forth through the the unstable L₃ point. BZ is moving retrograde with a rapid relative ~26 km/s velocity vis-a-vis all these other bodies.

To send a spacecraft to BZ would require a deep dive into Jupiter's gravitational field in conjuction with a velocity boost of ~6 km/s such that the rapid relative exit velocity is approximately: 27.5 km/s [= sqrt(66² - 60²)].
.

Ergo: While a ~6 km/s gentle nudge deep in Jupiter's gravitational field just might do the trick;
no gentle nudges deep in the Greek or Trojan camps
(or even in the vicinity of the unstable L₃ point) possibly could.