# Where to put a new planet **URL:** \ **Category:** Factual Questions\ **Created:** [November 25, 2012, 6:24pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081 "2012-11-25T18:24:51Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Korhut](https://avatars.discourse-cdn.com/v4/letter/k/bcef8e/32.png) [@Korhut](https://boards.straightdope.com/u/Korhut)\ **Post date:** [November 25, 2012, 6:24pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/1 "2012-11-25T18:24:51Z")
My 8 year old was considering building a new planet and wanted to know a good place to put it. I don’t know a good answer myself, but I know where to ask. Here’s my son’s first straight dope post: People say I can do anything. If that is true, it had better be scientific to create a machine that connects to your brain so you think of something and the machine will create it where ever you want it. So, if I can later, I will make this machine so I can create my own planet perfect for supporting life. It will be with the same area of Earth’s orbiting place. To make sure the planets do not collide, I will set it at the same speed of Earth, also being on the opposite side of the sun.How and will it’s gravity affect the other planets? What kind of life should live on it? Right now I am thinking of black, insect-like critters. What should I name it? ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [November 25, 2012, 7:05pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/2 "2012-11-25T19:05:24Z")
Perhaps it could be placed in an [co-orbital configuration](http://en.wikipedia.org/wiki/Co-orbital_moon#Co-orbital_moons), like Saturn’s moons [Epimetheus and Janus](http://en.wikipedia.org/wiki/Epimetheus_(moon)#Orbital_relationship_between_Epimetheus_and_Janus). Every so often, it would be relatively easy to transfer between the two planets. Another possibility would be to replace the Earth’s Moon with the other planet. You’d probably want to put the other planet farther away than the Moon, to keep the tides on Earth at the same size. Maybe give the Moon to Mars or Venus, just because. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 25, 2012, 7:33pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/3 "2012-11-25T19:33:30Z")
First off, it stretches the meaning of the word “possible” beyond recognition to say that it’s possible to have a machine that attaches to your brain so that you can create things just by imagining them. We haven’t a clue how to make such a thing, nor would I expect it any time in any of our lifespans. But to the question about planets: You _can_ put a planet in an Earthlike orbit on the opposite side of the Sun, but it’s unstable, like trying to balance a ball on top of a saddle. Put it there _just_ right, and it’ll stay there for a while at least, but if anything disturbs it the slightest bit out of position, it’ll start getting further and further out of position, faster and faster. This leaves a few options. First, you could position the new planet about 60 degrees away from the Earth in its orbit, so the two planets and the Sun form an equilateral triangle. This arrangement is relatively stable. Second, you could put the two planets in orbit around each other, with the pair of them in orbit about the Sun, as **ZenBeam** suggested, but it might not be possible to separate them widely enough to keep the tides down: Such arrangements are only stable if the orbit of the bodies about each other is small enough. And even if you could get it to work, you might get significant seasonal variations from the changing distance from the Sun. Third, if we’re going to be going to the trouble of making an entire planet from scratch, we could also install station-keeping thrusters on it, so that it could continually correct itself back into a balanced position. This is rather like how you can balance a yardstick vertically on your hand, by moving your hand around underneath it. Fourth, you could just accept that the planet’s orbit is unstable. I don’t see any reason why it would be important for it to stay on the far side of the Sun, so long as it stays at about the same distance. This is the Janus-and-Epimetheus configuration **ZenBeam** mentioned, and we already have a few asteroids which do this dance with us. Fifth, you could put your new planet at a different distance from the Sun, and change its properties in some other way to adjust the temperature to something Earthlike. For a closer planet, you could increase the albedo (i.e., making it shinier so it reflects away more sunlight), or put things in orbit to partly shade it, or shift your population centers closer to the poles. For a more distant planet, you could decrease the albedo, or set up a stronger greenhouse effect than the Earth has, or shift your population centers closer to the equator. ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [November 25, 2012, 7:46pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/4 "2012-11-25T19:46:50Z")
How about the asteroid belt? Collect all the asteroids together to make a planet [between Mars and Jupiter.](http://en.wikipedia.org/wiki/File:InnerSolarSystem-en.png) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 25, 2012, 7:55pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/5 "2012-11-25T19:55:51Z")
There’s not enough mass in all the asteroids to make even a planet as big as Mercury, much less the Earth. ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [November 25, 2012, 8:12pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/6 "2012-11-25T20:12:24Z")
It’s a start. I assume the mass of the proposed planet comes from somewhere; get the additional mass from there. My point was, by accreting the asteroids, it would make a nice clean orbit for the new planet. ---
**Author:** ![AndrewL](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@AndrewL](https://boards.straightdope.com/u/AndrewL)\ **Post date:** [November 25, 2012, 8:15pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/7 "2012-11-25T20:15:50Z")
A planet in the orbit of the asteroid belt would be a bit too far from the sun to be habitable. You’d probably have to put the life under heated domes or something. ---
**Author:** ![Washoe](https://avatars.discourse-cdn.com/v4/letter/w/ecae2f/32.png) [@Washoe](https://boards.straightdope.com/u/Washoe)\ **Post date:** [November 25, 2012, 8:26pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/8 "2012-11-25T20:26:50Z")
> [@Chronos](#): > > First off, it stretches the meaning of the word “possible” beyond recognition to say that it’s possible to have a machine that attaches to your brain so that you can create things just by imagining them. We haven’t a clue how to make such a thing, nor would I expect it any time in any of our lifespans. Dude, he’s eight years old. Cut him some slack. 😛 ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [November 25, 2012, 8:32pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/9 "2012-11-25T20:32:56Z")
A [Lagrange point](http://en.wikipedia.org/wiki/Lagrange_point) would be a good choice. The L4 and L5 points for the Earth-Sun system are nice, habitable zone and all that. You could build a good size fake planet there if the mass isn’t too large. (Think hollow.) There’s also the L4 and L5 points for the Earth-Moon system if you don’t want to go too far away, but the mass limit is lower. Plus since the Moon is already there, sort of why bother? Note that the L4 Earth-Sun point already has an [asteroid](http://en.wikipedia.org/wiki/2010_TK7) hanging around it. (It “orbits” quite far from the point, though.) That would be a nice starting mass. 300m is nothing to sniff at when building a “planet”. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [November 25, 2012, 8:40pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/10 "2012-11-25T20:40:20Z")
> [@Chronos](#): > > There’s not enough mass in all the asteroids to make even a planet as big as Mercury, much less the Earth. Every time a “quantum level decision” is made, the universe cleaves in twain, creating a vast pool of extra universes. So develop the technology to gain access to a few of these, and use them as a source of spare parts. **Korhut** ’s kid’s mind-machine could swipe an earth-like planet from one of those universes to experiment with. ETA: As **Korhut** ’s kid so presciently realizes, mind-machines like that have unlimited potential! ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [November 25, 2012, 8:48pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/11 "2012-11-25T20:48:50Z")
It’s been my understanding that Mars is within the “Goldilocks zone” where liquid water and therefore life is possible; it’s just too small and lacks a magnetic field so it lost its atmosphere. Get rid of Phobos and Deimos, then plop your new planet down right next to Mars so Mars becomes its moon. ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [November 25, 2012, 9:06pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/12 "2012-11-25T21:06:47Z")
Well, if we’re doing some extensive solar system renovation, why not move Mars to the asteroid belt and put the new planet in Mars’ orbit ? Make the new planet Earth-like, complete with iron core to generate a magnetosphere, but bigger, so it can retain a bigger atmosphere and thus retain more heat, to compensate for being farther out from Sol. Would that make it habitable? ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [November 25, 2012, 9:13pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/13 "2012-11-25T21:13:59Z")
> [@Northern\_Piper](#): > > Well, if we’re doing some extensive solar system renovation, why not move Mars to the asteroid belt and put the new planet in Mars’ orbit ? I wanted to keep Mars there as a moon because a large, close moon like Earth’s makes the planet’s axis much more stable\*. Plus a large red moon in the sky would be quite cool. 😃 \*The crust of Mars itself apparently back in its prehistory slid around on its then-molten mantle to its present orientation; that never happened to Earth because the tidal forces of the Moon stabilizes the present configuration. ---
**Author:** ![Michael63129](https://avatars.discourse-cdn.com/v4/letter/m/3da27b/32.png) [@Michael63129](https://boards.straightdope.com/u/Michael63129)\ **Post date:** [November 25, 2012, 9:17pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/14 "2012-11-25T21:17:14Z")
> [@Der\_Trihs](#): > > It’s been my understanding that Mars is within the “Goldilocks zone” where liquid water and therefore life is possible; it’s just too small and lacks a magnetic field so it lost its atmosphere. Get rid of Phobos and Deimos, then plop your new planet down right next to Mars so Mars becomes its moon. Actually, a magnetic field [doesn’t really do much](http://www.space.com/11187-earth-magnetic-field-solar-wind.html) to stop the solar wind from stripping the atmosphere away; Venus doesn’t have one either yet has an atmosphere 90 times denser than Earth, and is losing it at about the same rate; on Earth, the magnetic field channels the solar wind towards the poles, where atmospheric stripping occurs (the aurora are a visible manifestation of the solar wind hitting the atmosphere). ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [November 25, 2012, 9:22pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/15 "2012-11-25T21:22:02Z")
Interesting article, thanks for posting it. ---
**Author:** ![chappachula](https://avatars.discourse-cdn.com/v4/letter/c/d2c977/32.png) [@chappachula](https://boards.straightdope.com/u/chappachula)\ **Post date:** [November 26, 2012, 6:08am UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/16 "2012-11-26T06:08:55Z")
and an interesting kid, too! Thanks for posting. The kid’s gonna be one of us soon. ") ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [November 26, 2012, 6:36am UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/17 "2012-11-26T06:36:09Z")
> [@Chronos](#): > > This leaves a few options. First, you could position the new planet about 60 degrees away from the Earth in its orbit, so the two planets and the Sun form an equilateral triangle. This arrangement is relatively stable. This is my vote. Let your son know they’re called the Lagrange Points, and they’re places where two orbiting body’s gravity cancel each other out (in this case, the Earth and Sun). **Chronos** mentions L4 or L5. [Here’s where they are](http://en.wikipedia.org/wiki/File:Lagrangianpointsanimated.gif). These are an awesome seat for a new planet, but can I suggest L5 in case something goes wrong, Earth will have more time to correct the new planet’s orbit since it’s behind us… I’d rather a car accident happen behind me on a race track, than right in front of me. 😛 ETA: oops, somehow overlooked **ftg’s** post. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 26, 2012, 11:51pm UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/18 "2012-11-26T23:51:20Z")
Properly speaking, they wouldn’t actually be Lagrange points, since Lagrange’s calculations require that m1 \>\> m2 \>\> m3, and here, m2 ~= m3. That’s also why I said “approximately 60 degrees”: I’m pretty sure that there will still be _some_ stable configuration, and if so, it’ll be at _close to_ that angle, but it might not be exactly 60. ---
**Author:** ![RickJay](https://avatars.discourse-cdn.com/v4/letter/r/bb73d2/32.png) [@RickJay](https://boards.straightdope.com/u/RickJay)\ **Post date:** [November 27, 2012, 12:46am UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/19 "2012-11-27T00:46:06Z")
> [@Chronos](#): > > But to the question about planets: You _can_ put a planet in an Earthlike orbit on the opposite side of the Sun, but it’s unstable, like trying to balance a ball on top of a saddle. Why? If our imaginary planet - we’re playing magic here, so what the hell - is put into the same orbit as the Earth, just on the other side of the Sun, it should behave in the same manner. ETA: NM, figured it out. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [November 27, 2012, 1:05am UTC](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081/20 "2012-11-27T01:05:25Z")
> [@RickJay](#): > > Why? If our imaginary planet - we’re playing magic here, so what the hell - is put into the same orbit as the Earth, just on the other side of the Sun, it should behave in the same manner. > > ETA: NM, figured it out. Care to share? And wasn’t there a sci fi movie some decades ago about a hidden planet 180 degrees from Earth, so that we never knew of its existence. (I’m sure we’d have figured it out due to the influence on other bodies in our solar system, but still…) [Next page](https://boards.straightdope.com/t/where-to-put-a-new-planet/642081.md?page=2)