Starship Asterisk*

http://antwrp.gsfc.nasa.gov/apod/ap061107.html
Stunning photo!
The mathematics involved to capture this shot are incredible!
even if computer aided a HUMAN had to input the data required
Make your children learn Mathematics!! I tell my Grandchildren that they could be the first person on mars 8)
The teens and preteens of today are our future explorers!!! Mars is next and we need to prepare OUR Progeny for that moment

Agreed!

That photo is quite stunning, invigorating as well.
It makes me want to go discover something.

Unlike most photos, this one lacks a reference to the instrument which captured the photo. Could the authors please add this information to the caption.

Wadsworth wrote:Agreed!

That photo is quite stunning, invigorating as well.
It makes me want to go discover something.

Oh yes.
This gave me a lovely warm feeling inside when I saw it. Like meeting a friend I'd wondered about for quite a long time.
I remember watching 'The Sky at Night' on the telly as a boy many many years ago when Patrick Moore talked about the 'Shepherd' moons that swapped orbits and kept 'their' part of Saturn's ring system in check.
I watched a simulation on the programme of what happened with these two moons and wondered just how they knew how this could happen.
I still don't fully know even now but I'm getting there.
The story of these two moons is an amazing bit of 'space stuff' that is the kind of thing that reminds me why I'm fascinated by space and why I'm humbled by just how small and insignificant I am as an individual in our gigantic and wonderful universe.
Kinda puts that parking fine into perspective anyway...

Wadsworth wrote:Agreed!

That photo is quite stunning, invigorating as well.
It makes me want to go discover something.

The weirdest thing to me, is I can't put my finger quite on what is so stunning about it. Sure the technical challenge is awesome, but no more so than many of the other pictures we've seen.

There's just something about it that caused me to stop and say "whoa" the instant the picture loaded. I guess somehow it's more vivid than most.

I checked the Cassini website and found this:
http://saturn.jpl.nasa.gov/multimedia/i ... ageID=2337

Narrow angle camera
930 nm filter (infrared)
145,000 km distance
871 meters/pixel

I have to agree, it is a very stunning image. This one makes you go ooo too http://photojournal.jpl.nasa.gov/catalog/PIA08128
And this one shows just how Titanic a moon can be http://photojournal.jpl.nasa.gov/catalog/PIA07787

But I like this one best
http://photojournal.jpl.nasa.gov/jpeg/PIA07744.jpg

After reading the explanation in the APOD for 07/Nov/2006 "Janus: Potato Shaped Moon of Saturn", I got some questions. Since I am not an expert in Astronomy, I thought I'll post those questions here and get some feedback.

1). Is this orbit-swapping possible at a planetary level? It may not happen in our Solar System because of the distance between the planets. (Atleast the known ones. I am not sure of the KBOs). Perhaps in other stellar systems in our galaxy and other galaxies in the Universe?

2). If it cannot happen at a planetary level, what will be the reasons that can prevent it?

3). If it can happen, is it possible for both the planets to be in the habitable zone of their star? If not, can you please explain why?

Thanks

Karthik

It is possible to have planets "orbit swap", on the down side, swapping orbits cause drag by gravitational tidal forces making the orbits less stable. Over a long period of time the smaller planet will lose more orbital speed than the larger one and eventually will separate into unique orbits.

Threads merged.

iamlucky13 wrote:
The weirdest thing to me, is I can't put my finger quite on what is so stunning about it. Sure the technical challenge is awesome, but no more so than many of the other pictures we've seen.

There's just something about it that caused me to stop and say "whoa" the instant the picture loaded. I guess somehow it's more vivid than most.

One reason it has that 'woah' factor for me is its perspective. It gives you the feeling of being there suspended next to this huge floating rock. We don't see close-ups of floating rocks every day!! Much less in the back drop of a monochrome planet.

Please correct me if I am wrong but a planet orbit swap would be cause to no longer refer to the bodies as planets?

This reminds me of a question. Pluto is not in a stable orbit and will eventually leave our solar system -right?
Are we certain to what event(s) caused its orbit and do we know in fact, that it never was part of the inner planetary system of our star

Anyway, I also enjoyed the above mentioned APOD. I found myself pausing and looking at the image for quite sometime.

Orbit swapping is not the same as bodies orbiting each other in the case of Pluto, so they would fall under the definition of a planet.

It is the Earths Moon that has the unstable orbit, drifting slowly away, in 3 to 4 billion years it may become its own planet. If the Moon does leave Earths orbit who gets to give it a planetary name? Any suggestions?

Selene : is my contribution.

I'D keep it as Luna! Why change it's name?
Orin

Dr. Skeptic

Did you misunderstand me because you did not type one word that addressed my questions?

The orbit swap was a response to an earlier reply in this thread. It had nothing to do with Pluto!

The Pluto question is legitimate. Pluto's orbit will take it out of our solar system. What caused its orbit and is it possible that it may have been part of our inner planetary system earlier in the life of our system?

Wow, it looks like I just typed the same thing that I did earlier.
Let's try this again shall we

I don't ever remembering reading anything pertaining to Puto's orbit that would cause it to leave the solar system. Where did you aquire that information?

Pluto (and Charon) fails as planet/moon because the barycenter of their orbits does not lie within either spheres' mass: the center of gravity of their local system can be located in the empty space between the two bodies.

In a planetary orbit swap, the planets would exchange positions in the solar system which would not be a disqualifier for planet status.

I don't believe that Pluto was part of the inner planetary system, as a quick overview this is the "safest" answer.

As our Sun merged from a protostar to an active star, strong solar winds force the accretion disk away, the lighter elements (H, He, O, C ...) were pushed farther, heaver elements (Fe, Ni, Cu, Zn ...) is in higher concentration closer to the Sun. The average density of the planets lessen as the distance from the Sun increases - Mercury = 5.427 g/cm³, Mars = 3.934 g/cm³, Neptune = 1.638 g/cm3. The Kuiper Belt appears to contain predominantly frozen H2O and light hydrocarbons, (including Pluto), that may have moved along the solar winds as gasses or as resididual interstellar "stuff" from our corner of the Milky Way.

Pluto may have been a somewhat large Kuiper Belt object that was caught-up in Neptune's gravitational field and "flung" out of the orbital plane increasing its rate of encounters with other Kuiper Belt objects increasing its size and it's moons. There is no evidence of Pluto having a large amount of heavier elements placing it's creation closer to the Sun.

Did I hit your question this time?

Yes it did thank you.

I will have to research where I found Pluto's orbit info. I will get back to on that one. Perhaps I am mixed up some info?