Mike Brown's Planets

Nice post and mine opinion is that planets needs t...

2012-01-10T01:30:28.075-08:00

Nice post and mine opinion is that planets needs to be classified according to just two things, density and size.

The Pholus Aphelion Orcus Orbit synchronization pi...

2012-01-09T22:55:45.472-08:00

The Pholus Aphelion Orcus Orbit synchronization pictured in the website below: http://www.lunarplanner.com/Images/asteroid-orbits/Pholus-Saturn-Orcus.jpg

points in the same general direction of the sky as the aphelion of Sedna. When you couple with with other data (such as Pluto incline), what does that indicate to you?

Nobody knows the hour or the day that the lord God...

2011-12-29T23:27:23.992-08:00

Nobody knows the hour or the day that the lord God will bring the end of the world Dec 21 2012... even the angels even the Son of God Jesus Christ himself doesn't know...only the Father in Heaven... My fellow Brother's and sister's....

Johh. I'll try harder next time :) Rudy

2011-12-09T23:13:13.859-08:00

Johh. I'll try harder next time :)

Rudy

With New Horizons on it's way to Pluto, we are...

2011-12-08T05:00:29.483-08:00

With New Horizons on it's way to Pluto, we are soon going to have a probe out there. I think it'd be a good idea to use New Horizons to look for more Dwarf planets, because it is so much closer, we'd see more. The again, its not a telescope. But I believe next time we send something in to the Kuiper belt, we should equip it with a small telescope and see if we can find anything.

Thank you, KenN and djlactin, for your explanation...

2011-12-02T09:52:48.109-08:00

Thank you, KenN and djlactin, for your explanation of diameter estimation from star transits.

Rudy, that didn't help!
John

Screw that, the Solar System is a huge place! Ther...

2011-11-16T12:21:11.036-08:00

Screw that, the Solar System is a huge place! There's room for everybody, even Sedna (and maybe Tyche)!

The primary planets in the Solar System are: Mercu...

2011-11-11T06:06:57.173-08:00

The primary planets in the Solar System are: Mercury, Venus, Earth, Mars, Vesta, Juno, Ceres, Pallas, Jupiter, Saturn and Uranus.

The primary planets in the Solar System are: Mercu...

2011-11-11T05:32:05.162-08:00

The primary planets in the Solar System are: Mercury, Venus, Earth, Mars, Vesta, Juno, Ceres, Pallas, Jupiter, Saturn and Uranus.

Hi Mike,..Didn't you participated on atempt to...

2011-11-09T10:19:47.468-08:00

Hi Mike,..Didn't you participated on atempt to observe asteroid 2005 YU55?

http://www.universetoday.com/90805/live-webcast-as-keck-telescope-attempts-images-of-asteroid-2005-yu55/
much smaller eccentricity but direction cca like Elenin,..Pavel

I believe that the matter of size (if by size you ...

2011-11-02T16:00:48.336-07:00

I believe that the matter of size (if by size you mean "diameter") is in itself problematic.

Let me elaborate a bit more.
Unless both Pluto and Eris are perfect spheres and not someting more akin to a triaxial ellipsoid or even a pear shaped body, there in not only one dimension that can emcompass size.

If you want to go by "size", meaning the M in the Système international of units, then you would have to have it as "diameter of a sphere with equal volume". So there is no Pluto being "bigger" than Eris by one centimeter, inch, foot or meter. It could well be that Pluto's largest dimension is larger by 2 kms. than on of the "diameters" of Eris but contrarywise there is a shorter dimension accross Pluto which 1 Km. shorter than the longest dimension on Eris.
At the end of this comment the issue is that the answer to the question of which is bigger? Might be "what is it meant by bigger?
Bigger equatorial diameter? Bigger ESD? (Equivalent spherical diameter)
If One of the bodies is 2326 +/-12 Kms. and the other is 2400 +/- 50 Are this numbers refered to ESD (equivalent spherical diameter)or to one maximal chord?
What is uncontroversial is that ERIS IS 27% MORE MASSIVE THAN PLUTO.
As a corollary we can say that the eridian density is at least 20% greater than the plutonian.
Lets just hope that New Horizons can give us estimates of Pluto's J2 at the end of the day.

Rudy

Pluto and Eris are neither twins nor rivals. Why d...

2011-10-31T19:26:39.613-07:00

Pluto and Eris are neither twins nor rivals. Why does everything have to be a contest? Earth and Venus have similarities, as do Uranus and Neptune. And how can we be certain which object is bigger unless and until we visit BOTH of them? Yes, Eris is a lot further away, but we should at least start thinking about a mission there. Every mission has taught us that we don't really know much about a world until we go there. The whole notion of having to make a decision based on which object is bigger ends up being downright sily, just like the idea of "bragging rights." These are all planets of our solar system; they are all different, but they are all fascinating. And I disagree about their not being interesting to people. Clearly, all this coverage and all the books and articles that continue to be written show that the outer solar system is a place that interests a great number of people. I think there will eventually be a reconsideration of the IAU vote to allow for the inclusion of dwarf planets and of exoplanets as well.

What I appreciate most about you and your work, Dr...

2011-10-31T13:24:42.432-07:00

What I appreciate most about you and your work, Dr. Brown, is that you put great care and emphasis on accuracy, no matter how popular/unpopular that stance is.

Seems to me that saying Eris and Pluto are alike because they are roughly the same size is like saying two people are alike because they are both 5'-11" tall--even though one weighs 300 pounds with blond hair and blue eyes, and the other is a dark-eyed brunette who is height-weight proportionate. Seems like it's a weird way to try to correlate two very dissimilar objects via one of their very few common denominators...

I've also heard Venus described as "Earth...

2011-10-30T19:12:14.961-07:00

I've also heard Venus described as "Earth's Evil Twin". It occurs to me that twins don't have to be identical. They merely have to be siblings born from the same mother at the same time.

Presumably, Earth and Venus formed more or less together, and likewise Uranus and Neptune. How about Pluto and Eris?

Bob Shepard of Denver

It would be really ridiculous to the point where I...

2011-10-30T17:03:22.083-07:00

It would be really ridiculous to the point where I LOL, if in three years New Horizons identifies and proves that Pluto is not only larger than Eris, but the largest of the known dwarf planets, even if by an inch. If this is the case, all who identified Eris as the larger of the two, will have egg on their face for bringing the sudden and urgent need to create new definitions and classifications for planets to the IAU.

Okay, so density is far superior and important to me, as a drop of matter from the center of a black hole, may contain more matter than the entire Milky Way (except for the black hole at the center of The Milky Way) . Most interesting prospects for life sustaining worlds (in our solar system) include Enceladus, Europa, Ceres and Titan, all of which are much smaller than a gas giant such as Saturn, whose density is less than that of water.

I do not care if a world is the size of a marble if it harbors life. Although it is possible that life exists on gaseous worlds, I think the scientific community believes it to be improbable (perhaps based on our narrow- minded view of what life needs to exist), therefore less likely to exist on such a world.

Is it not mass that determines a world's shape, size, ability to clear its neighborhood etc.; it's certainly not a condition of size alone; as with Saturn, of great size does not mean of great density.

So what if Eris is 27% more massive than Pluto, what does it point to regarding differences in their origin, age, composition or other things of interest? Specifications of a world can be interesting, but what science can do with such information can be very interesting. Answers to questions such as "how can worlds which reside in the same region be so different (if this is the case)," "how were such worlds made" and "what is the natural history of these worlds," is of greater interest to me.

I am not going to be waiting on the edge of my seat for New Horizons to make precise measurements of small frozen, red, blue or purple worlds. There is a lot more out there than we can know at this time, but one thing is for sure, we will continue to find worlds, because there are an infinite amount of them in the universe, just waiting to be discovered.

May the search continue, forever...

Hi Mike,...what do you think about these works:htt...

2011-10-30T01:15:19.761-07:00

Hi Mike,...what do you think about these works:http://arxiv.org/PS_cache/arxiv/pdf/1102/1102.0212v6.pdf ?
(On the anomalous secular increase of the eccentricity of
the orbit of the Moon,...)
Did you find or could you find any similar disproportions in motions of planetoids (Eris, Sedna,Pluto,..)? Pavel Smutny

did mike brown has studied why there is a lot of O...

2011-10-29T09:38:42.179-07:00

did mike brown has studied why there is a lot of Objects around 67 UA?????

Congratulations on the accuracy of your measuremen...

2011-10-29T02:48:29.800-07:00

Congratulations on the accuracy of your measurement!

I would have given you the gold star you request, but I have this feeling you'd actually prefer a ball of reddish, dirty ice instead... :-)

@mikeemmert: The Moon doesn't have the same de...

2011-10-29T01:20:28.092-07:00

@mikeemmert: The Moon doesn't have the same density as the Earth, either.

This situation is expected when a satellite is created by a collision of a smaller body with that of a differentiated larger body. The satellite ends up being composed of bits of the smaller body (usually less dense than the larger body) plus surface (less dense) bits of the larger. Hence it's no surprise when a satellite is less dense than its primary.

Re: transit estimation of diameter. If you have t...

2011-10-28T23:38:15.905-07:00

Re: transit estimation of diameter. If you have two observations of the transit from different locations, the timings of the star winking out and back on give two chords. The four endpoints of the chords uniquely define a circle (even if neither of the chords corresponds to the diameter). Estimate quality would increase with the number of observations/chords, but I think even one full chord and a tangent point would suffice.

John D, in reports I have seen, there were multip...

2011-10-28T15:18:32.824-07:00

John D,
in reports I have seen, there were multiple measurements from a few observatories so combining them revealed longest transit as diameter.

JohnD said...

How do you know the chord across which Eris' disc crossed the star? Are your 'ephemera' for Eris (? orbital data) good enough to be certain where it is between a diameter and a tangent?
JohnD

Size does matter. I have a bright yellow t-shirt ...

2011-10-28T10:21:11.004-07:00

Size does matter. I have a bright yellow t-shirt with bold black letters that says it does :D.

Jupiter and Saturn vary by mass, size, and density. They vary so much that it would be difficult to say they share a common history and origin, but they do. Saturn is a little less than a third the mass of Jupiter. Unlike KBO's, the mass of a gas giant is quite dependent on mass. Extra mass means extra gravity and that compresses the gas Jupiter is made out of so it's denser.

The assumption you make in this post, Mike, is that once Pluto and Eris formed, they would keep the same density they formed with. I beg to differ. Pluto has moons and the arrangement of them suggests that it has undergone a collision. Eris has one moon and it's smaller than Pluto's. Perhaps it has also undergone a collision. Haumea has very definitely undergone a collision.

At this point I would like to respond to the anonymous poster who has heard that Triton is referred to as "Pluto's twin". That idea has been around longer than Eris and Haumea (at least in the consciousness of Man). At the time this was most popular, it wasn't considered important that in fact, Triton is about 60% more massive than Pluto. They were still considered twins.

The mass of Triton is equal (or about as equal as sort of narrow error bars can be) to the mass of Pluto plus the mass of the four major moons of Uranus. Since Neptune has a ring system that orbits around the planet's equator and a moon, Proteus, that does the same, how does Triton's backwards orbit fit in to all this?

Why is the Neptune moon system so different from that of the other three gas giants?

If Triton is in fact an interloper from the Kuiper belt, then it's mass can be accounted for by a Pluto sized object accreting the original moons of Neptune. Triton is orbiting at the same place with regard to Neptune as Uranus's four moons are with respect to Uranus. That's a strange coincidence, isn't it? Or is it?

Uranus and Neptune are pretty much considered twins, too, mostly because they're about the same size. The axial tilt is much greater for Uranus, though, in fact it spins slightly retrograde. I used to think it was hit by four Pluto-sized bodies but then I took angular momentum in Physics class and was awakened from my stupor by an internet question by Miss Julie Williams from the United Kingdom. Four Pluto sized bodies, even with perfect limb-grazing shots, will not turn Uranus over on it's side. It would take an Earth mass body and even then you need a perfect limb shot. There's some other explanation for Uranus' tilted spin. And that explanation is, uh, gee, I don't know :?

If the explanation for Pluto's and Eris' moons' existence is a collision then they would not neccessarily wind up with the same density. There might be other reasons for different densities, also, for instance Pluto approaches closer to the Sun than any of the objects mentioned here except Uranus, so sunlight sublimating ices off it's surface would result in different densities.

Since this is gettin almost as long as Mike's post, I would like to close with the kicker:

Charon does not have the same density as Pluto.

the amount of objects greater than an half thousan...

2011-10-28T06:12:36.816-07:00

the amount of objects greater than an half thousand miles are growing in the solar system! I know that nerd scientifics do not care about name of scientific object! but when 2007 OR10 will have a real name for this object came into the common world and not only into the nerd world where the nature are only numbered sampler for scientific purpose and glory !

I've heard Triton referred to as "Pluto&#...

2011-10-28T05:45:14.777-07:00

I've heard Triton referred to as "Pluto's twin." How does it really compare to Pluto and Eris?

How do you know the chord across which Eris' d...

2011-10-28T02:36:54.095-07:00

How do you know the chord across which Eris' disc crossed the star? Are your 'ephemera' for Eris (? orbital data) good enough to be certain where it is between a diameter and a tangent?
JohnD