# Tag Info

24

There were three attempts to measure Arrokoth by occultation, and the June 3rd attempt didn't detect anything. The July 10th attempt had a tiny blip, that appeared to be in the "wrong place", well away from the location that astrometry had predicted. The July 17th occultation was successful, it determined the shape and location well. Some thought ...

22

Here's my answer. I'll try to make it as comprehensive as possible. It's pretty hard to define the edge of the Solar System. Most people would probably define it as where objects are no longer gravitationally bound to the Sun. That just shifts the question a little, though: Where is that dividing line? To try to answer this, I'll go over the regions of the ...

14

Yes, but they're not very good and they're amazing. The Wikipedia article for Pluto shows a low-resolution map of the surface, generated from Hubble images: And the Wikipedia article for Pluto's largest moon Charon shows a low-resolution map of the Pluto-facing side of Charon (not to scale): Larger image here. Only the Pluto-facing side is shown because ...

12

Whenever I see this question discussed, it seems that the heliopause, or some variation thereof, is given as an answer -- and then it's mentioned that the Oort Cloud extends beyond it. A more correct answer, therefore, should be that it ends at that distance at which objects are, for all practical purposes, no longer bound to the solar system barycenter. ...

12

According to Wikipedia: A preliminary analysis of all collected data suggested that Arrokoth was accompanied by an orbiting moonlet about 200–300 km (120–190 mi) away from the primary. It was later realized, however, that an error with the data processing software resulted in a shift in the apparent location of the target. After accounting for the bug, the ...

11

It's probably a cosmic ray strike, a common artifact on New Horizons images. The image, however, is of very poor quality which makes it difficult to analyse the exact nature of the spot. I'll go into this more at the end of the answer. Possibilities: Cosmic ray hit A common occurance (see below); the most likely cause without evidence to the contrary. ...

10

Light flux decreases as one over distance squared. So if Eris is 100 times further away from the Sun than the Earth is, then the amount of light that reaches Eris is 10 000 less than that on Earth. Since a difference of five magnitudes is a factor of 100, The Sun would have an apparent magnitude -16.7 seen from Eris' aphelion, as opposed to -26.7 magnitude ...

9

You are correct that the IAU definition of "clearing the orbit" has the problem of being not explicitly quantified. And a complete clearing was obviously never the intention behind the definition. I like this statement by Steven Soter: The IAU definition of a planet as a heliocentric body that "has cleared the neighborhood around its orbit” is problematic....

8

This was a hard one to answer, primarily because of the difficulty in tracking down information. The Observations of MU69 The extended mission for New Horizons involved adjusting its orbit to do a close fly-by of a Kuiper Belt Object (KBO). The annoying part about this was that they needed to find one first! Ground based observations were unsuccessful due to ...

8

It was the first thing I thought too, but I would say it won't count in the statistics. The earlier paper by Batygin & Brown was talking about bodies orbiting further out. 2015 RR245 orbits between 33.7 and 129 AU. The "cluster" of bodies considered in the paper have aphelion distances from 150 AU upwards. So I think it would be a mistake to try and ...

8

Estimates of Planet 9's orbit currently suggest that it doesn't have any major effect on the Kuiper Belt, because its orbit is too far away and on a different plane than the Kuiper belt, and from the inner Oort cloud, at 200 and 1200 aphelion and perihelion, However it does have an effect on Trans-Neptunian objects that transit through the Kuiper belt. It ...

8

It is a planet - either a gas giant core, a mini-Neptune, or a super-Earth. First off, Mike Brown has stated outright “It is a planet—there’s virtually no doubt,” he said. “What we now call planets are objects that can gravitationally dominate their neighborhood. Pluto is a slave to the gravitational influence of Neptune. By area, Planet Nine dominates ...

8

Yes this is possible and has been tested by the TAOS (Transneptunian Automated Occultation Survey) group among others. That group is in the process of building the TAOS-II project which will use several telescopes and fast readout CMOS cameras (since the occultations only last a few seconds) to search for occultations caused by unknown Kuiper Belt Objects. ...

7

Possible rendezvous with a Kuiper belt object and Voyager type data on the heliosphere: "We should have power until the 2030s, so we can get into the outer part of the heliosphere," says Spencer. "As long as we can continue to get good data—and persuade NASA to pay for it—we will keep getting the data, because we will be in a unique environment that we've ...

6

To answer this, let's visit Kepler's third law which tells you the orbital period of a body, if you know how far away it is. $$\frac{P^2}{a^3} = \mathrm{constant}$$ As it turns out, if you use the correct units, for the orbital period, $P$, and the semi-major axis, $a$, namely years and astronomical units (AU) respectively, then that constant is equal to 1!...

6

(I have tracked down the reference that I made in my comment on the question.) Presumably earth rocks once blasted into space (by volcanism or meteorite impact) gain or lose energy primarily by orbital interactions with planets or moons. Since these interactions will occasionally give enough energy to escape the solar system entirely, presumably anything ...

5

Yes there is a difference, Kuiper Belt Objects (KBOs) are a subset of Trans Neptunian Objects (TNOs). Other subsets are Oort-cloud objects (OCOs) and scattered disk objects (SDOs). These are not KBOs but they are TNOs. See for instance this wikipedia page.

4

While the answer by @zephyr is extensive, unresolved images of a very distant Kuiper belt object distant body over a short arc of it's orbit through a single filter can not be used to calculate a color. Further, contrary to the claim in that answer, there are indeed a series of measurements alternating between visible and infrared filters! The Sci-News ...

4

The recent evidence for the 9th planet is an alignment in various parameters of known Kuiper belt objects. These are not Kuiper belt objects. The Kuiper belt is taken to refer to the neighborhood of Neptune resonances. The scattered disc is another population, further out, and the objects relating to Planet 9 are further still. Legend: grey = Kuiper belt, ...

4

"Moons" is a misnomer here, the majority of Kuiper Belt Objects (KBOs) with companions are binaries. Now there are several populations in the Kuiper Belt, characterized by their eccentricities and inclinations. The cold classicals are hereby the most important ones, having mostly circular, low inclination orbits and a high binarity fraction of ...

3

I'm not speaking from an informed position here, but two things come to mind. First is that a rogue planet is likely to be traveling very fast, relative to our solar system. An object from within our solar system (a Kuiper/Oort object) is going to have an orbital velocity. Something that isn't a part of the system at all could be traveling much, much faster....

3

The idea is basically to look for comets coming from the same direction. Look for a pair of comets that at some time earlier in their orbit was at the same place at the same time. That is a data point, but an extremely inaccurate one. It does not have to mean anything, and you are going to collect a large amount of statistical noise. For this purpose, normal ...

3

The main problem with determining an object's orbit is we only know the position with certainty in two dimensions. The distance to the object is largely unknown. This accounts for the large uncertainty in the period of newly discovered TNOs. Many possible orbits could fit the early observations, and therefore the uncertainty is large. As time goes on, ...

3

The Kuiper Belt is fairly large (with inner and outer radii $\sim30\text{ AU}$ and $\sim50\text{ AU}$), but it does not contain much mass. The total mass is likely somewhere between $0.01$ and $0.1$ Earth masses[1], [2], which is essentially a mass range from five times the mass of Pluto to the mass of Mars. Now, it was likely much more massive in the past - ...

3

Wikipedia lists some of the most farthest objects from the sun in the solar system. The third farthest object "Eris" was the subject of one of the most distant stellar occultations observed from Earth. From this occultation, its diameter, density and albedo was calculated. On 6 November 2010, Eris occulted a faint star (V $\sim$ 17.1) which was ...

3

The gravitational region around the planets isn't hard to calculate, sometimes called the Sphere of Influence, sometimes called the Hill Sphere. They're calculated differently but they define pretty much the same idea. The actual long term stable region is somewhere around 50% of the Hill Sphere. A gas giant like Jupiter simply doesn't have a large ...

2

This is the result of a new way to investigate the images taken by the PanSTARRS survey, see Weryk et al. 2016. A second batch of new discoveries was issued on July 26. This has been planned for several years, and now there's enough data to get useful results. Note that Gareth Williams from the MPC has currently some technical problems with the most recent ...

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