# Planetoid Sedna

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#### mkmilion

##### Well-Known Member
I just wondering why no one has picked up the topic about the new planetoid Sedna. I can't believe it!! It excites me. I is said to be 800-1000mi in diameter and it is so far away that the Sun could be blocked out with a pinhead. It's avg. temp. -440*F, in the summer -420*F. The oldest and farthest known object in the our solar system.
I be sure to post with any more input.

#### WiK

I'd heard from a guy at school they'd discovered a new planet... I couldnt find it on the BBC News site, so I thought it was just a rumor and forgot about it.

Well I think we can be *pretty* sure there is no life on there

Argh, now any question on an exam (I have several coming up in May) that says: How Many Planets In The Solar System" could be seen as a trick question. Would the marking sylabus be updated in time and every science teacher tell the students about it?

Dont mind me panicking

Phil

#### mkmilion

##### Well-Known Member
To tell you the truth it currently would still be nine. Due to the fact that they haven't decided if it falls under the definition of a planet. Thus the term planetoid.

#### jflis

##### Well-Known Member
well.... you *may* want to say *8*, cuz the jury's still out on Pluto for that matter...

#### Chr$##### Well-Known Member Maybe there's a Stargate on it. #### Bobrogg ##### Well-Known Member I say, lets have a contest. The first one who can cert. L-1 on Sedna will win a cash prize. I'll kick in one dollar to start; we will put the cash into a saving account and by the time we get there the interest from that dollar should be a huge sum. #### n3tjm ##### Papa Elf Originally posted by Chr$
Maybe there's a Stargate on it.
Hehehe...

Hope nobody tries to visit there .

#### Ryan S.

##### Well-Known Member
they have actualy known about this for a long time, according to my old astro teacher. There is an equation somoeone made up that predicts where planets are, and by whatching the movments of other objects, the effects of the 10th planets gravity can be seen.

This is just the firsst time they have seen it.

Nothing can escape gravity

#### DavRedf

##### Well-Known Member
I dont think it can be a planet as most moons are bigger than that.
Also I think that at that distance the gravitational attraction of the sun would not be enough to hold a mass that small so it could well not even be a member of our solar system.
Having said that I dont think level 1 has a chance, level 3 maybe

Or one of Neil's water rockets

David

#### Ryan S.

##### Well-Known Member
LOL

I am not sure.....if we knew the mass of the planet and the distance we could always figure it out

(G x M1 x M2)/D^2=FofG

That is a varient of F=MA but you dont simply have the MA

I think that is the right equation

I would think there would be enough gravitational force, also, it is also being pulled in by al the other planets, maybe not a ton but that is more than the sun alone

#### Chr$##### Well-Known Member Did anybody catch the Gate Address? #### hokkyokusei ##### Well-Known Member Originally posted by Chr$
Did anybody catch the Gate Address?
OK, so we have Egyptian gods, Norse gods, now you want to throw Innuit god(esse)s into the mix? Bring 'em on!

#### mkmilion

##### Well-Known Member
Originally posted by Ryan S.
LOL

I am not sure.....if we knew the mass of the planet and the distance we could always figure it out

(G x M1 x M2)/D^2=FofG

That is a varient of F=MA but you dont simply have the MA

I think that is the right equation

I would think there would be enough gravitational force, also, it is also being pulled in by al the other planets, maybe not a ton but that is more than the sun alone
I know that it's 8 billion miles from the Sun. Can you get mass from the diameter of a sphere?

#### jflis

##### Well-Known Member
nope, not without knowing the composition. Compare a bowling ball to a basket ball...

If we had some of the orbital mechanix defined, you could derive the mass from that

#### saxophone

##### Well-Known Member
Actually, our solar system only has 4 planets. The rest is just
rubble and residue.

#### rkt2k1

##### Well-Known Member
I saw a report on the Science Channel regarding Sedna and they stated that it may have it's own moon. If so, they stated that would put it into the planet category, even with it's small size. I think it's real significance is to show everyone that there are still so many discoveries out there to be made!

#### graylensman

##### Well-Known Member
Originally posted by rkt2k1
I saw a report on the Science Channel regarding Sedna and they stated that it may have it's own moon. If so, they stated that would put it into the planet category, even with it's small size.
Okay, so what about asteroid Ida and its moon, Dactyl? Hmmmm?

I think it's real significance is to show everyone that there are still so many discoveries out there to be made!
"There are more things in heaven and earth than are dreampt of in your philosophy, Horatio."

##### Keel Loopy
Originally posted by graylensman
"There are more things in heaven and earth than are dreampt of in your philosophy, Horatio."
"My Favorite Year", right? A quote from the great Alan Swann?

#### jflis

##### Well-Known Member
Well, having a moon isn't a definitive for being a planet. There are many asteroids in the asteroid belt that have smaller bodies orbiting them. Even Pluto has Cheron, but it has been unofficially classified as something other than a planet.

A number of factors, including size, goes into the definition and one of them is the nature of the orbit (circular or nearly so, within a certain percentage of the plain of the ecliptic, etc)

Really, what it boils down to is a word game. We call the earth a planet and our moon a moon because it is small and it orbits the earth, yet neither is true.

The moon may be smaller than the earth, but it is very large compaired to 99% of the bodies in the solar system, *and* the moon does not orbit the earth, rather the earth and moon orbit about a comon center of gravity. It is just as accurate (or inaccurate, as the case may be) to say that the earth orbits the moon as it is to say that the moon orbits the earth.

Of course the same is true of the planets orbiting the sun, etc, etc, ...

jim

#### graylensman

##### Well-Known Member
JFlis

your point is well taken. I read a quote from an astronomer who pointed out that Pluto should always remain a "planet" because that's what it was originally designated, end of discussion. Perhaps if Lowell had discovered a bunch of Trans-Neptunian Objects at the same time, the matter may be otherwise.

"My Favorite Year", right? A quote from the great Alan Swann?
No, actually it's Shakespeare, from "Hamlet."

#### Ryan S.

##### Well-Known Member
Originally posted by jflis

Really, what it boils down to is a word game. We call the earth a planet and our moon a moon because it is small and it orbits the earth, yet neither is true.

The moon may be smaller than the earth, but it is very large compaired to 99% of the bodies in the solar system, *and* the moon does not orbit the earth, rather the earth and moon orbit about a comon center of gravity. It is just as accurate (or inaccurate, as the case may be) to say that the earth orbits the moon as it is to say that the moon orbits the earth.
O great point Jim, the thing is we dont really notice this as much with the earth and moon because the CG is actually in the earth, just off to the side. The real way orbiting works is more apparent in Cheron and PLuto, or Binaries. If you have ever seen videos or animations, you will see they orbit a point that neither ever touches. It would be like putting two balls on the end of a dowl and putting the dowel on another dowel (at the CG and spinning them. Its really cool to see the videos of Cheron and Pluto, weird but cool

#### jflis

##### Well-Known Member
You should have seen the discussion i had with one of my professors when he commented in class (trying to make a point about how some things are fact and some things are "just accepted"), he used an example of droping a piece of chalk and watching it fall to the floor. He then stated something to the effect "now, we can SEE the chalk fall to the floor so we accept that fact as being real whereas other things that we can't perceive so easily... etc...)

later on, in a write up about the class, I pointed out that our acceptance of that "fact" is just another misconception due to a lack of proper perception...

you see, the chalk doesn't actualy fall to the earth. rather, the gravitational attraction of the earth pulls the chalk (from our perspective) *down*. BUT, what is never acknowleged is the fact that there is something else happening. Specifically, the gravitational attraction of the CHALK is also pulling the earth UP. They meet someplace in the middle (specifically, at the CG identified at the point the chalk was released). I even went so far as to calculate how far the earth was pulled toward the chalk before they hit

I don't know if he loved me or hated me for that side of me... LOL

It takes enormous energy to move a mountain, but to move the earth, you mearly have to drop something...

#### KermieD

##### Well-Known Member
Originally posted by jflis

I don't know if he loved me or hated me for that side of me... LOL

It takes enormous energy to move a mountain, but to move the earth, you mearly have to drop something...
I don't know bout love or hate, but that side of you just scares the bejeezus out of me!

#### graylensman

##### Well-Known Member
Jim, I had a similar experience in 9th grade science. The teacher told us that the moon doesn't revolve since it keeps one face to the earth at all times. I spoke up and said, no, it revolves once per revolution. When he stilldidn't believe me, i got out of my chair and proceeded to "orbit" the classroom, face toward the center of the room.

It convinced my teacher that the moon does revolve and it convinced my so-called "peers" that i was a dangerous freak to be avoided at all costs.

#### jflis

##### Well-Known Member
LOL

Yep, my daughter and I call it the "Asimov Syndrome"...

Those of you who read a lot of Asimov will know what I mean.

If we ever get together, remind me to show you a nice proof that 1 = 2 (no tricks) and that time travel is not only *possible*, it's already occured

#### saxophone

##### Well-Known Member
> remind me to show you a nice proof that 1 = 2

Is that the proof that involves dividing by zero?

#### kenobi65

##### Well-Known Member
Originally posted by jflis
If we ever get together, remind me to show you a nice proof that 1 = 2 (no tricks) and that time travel is not only *possible*, it's already occured
Reminds me of the quote, "2+2=5, for very large values of 2."

#### jflis

##### Well-Known Member
Originally posted by saxophone
> remind me to show you a nice proof that 1 = 2

Is that the proof that involves dividing by zero?
no, the proof you are speaking of is based on a falacy or an error in math so it isn't really a proof.

#### Ryan S.

##### Well-Known Member
id liked to hear that at a CMASS launch Jim, sounds interesting, I have heard some theories about time travel, I know we can see through time but I am not sure where we have travelled through time.

BTW I like the chalk story LOL...