[Petrochemicals (OP)]

As in the 1969 film

https://m.imdb.com/title/tt0064519/

Is there a planet the other side of the sun that we cannot see ? Do we have visual confirmation. I will accept gravitational effects and orbital acceleration as conjecture

Also mods this is a serious question of physics, and its at least 49 years old so it is not a new theory.

[Bored chemist]

It would affect the orbits of other planets and we would have noticed that effect (unless it was really small).
I suspect that some of our space telescopes would have seen it (again- unless it was really small), but it's fair to say that if he telescope was "near" Earth and given that we don't point telescopes at , or near, the Sun, we might have missed it unless one of the cameras looking at Mars or something spotted it.

[PmbPhy]

As in the 1969 film

https://m.imdb.com/title/tt0064519/

Is there a planet the other side of the sun that we cannot see ? Do we have visual confirmation. I will accept gravitational effects and orbital acceleration as conjecture

Also mods this is a serious question of physics, and its at least 49 years old so it is not a new theory.

It's a good question no matter how old it is. However a planet would cause perturbations of Mercury and Venus which would don't see.

[syhprum]

This is an old idea but such an orbit would be very unstable and could not last long.

[Janus]

The point just opposite the Sun in Earth's orbit is Earth's  Lagrangian point #3
However unlike points 4 and 5, it is not fully stable.   An object put there would stay there only if it is left completely undisturbed. Think of it as a needle balanced on its point.  The slightest nudge of any kind and it will topple over.
Basically this would require the Solar system to be completely empty other than for the Sun, Earth and this object.   

In the real solar system, the object would be nudged out its L3 point, and once that happens, its tendency will be to continue drifting further and further from the L3 point.
One interesting possible outcome from this is that it ends up in a "horseshoe" orbit.
 Let's say that it gets nudged into a slightly lower orbit.  This will be faster orbit than the Earth's so it will start to catch up to the Earth.  As it gets closer to the Earth, the pull of Earth's gravity on it will get stronger and tend to pull forward on it.  This forward acceleration will have the effect of lifting the object to a higher orbit. A higher orbit is a slower orbit.  So oddly enough, the net effect of the Earth pulling forward on it is to slow it down.  It can even rise to an orbit that is further the Sun than the Earth and start to lose ground, with the Earth pulling further and further ahead of it.
Eventually the Earth gets so far ahead, that it is coming up from behind the object, threatening to "lap" it.  But now its gravity is pulling back on the object, causing it to drop into a lower faster orbit.  Now it picks up speed on the Earth and starts to pull away until it starts to catch up with the Earth once more and everything starts all over.

This is not just theoretical either.  The Earth already has a few asteroids in this type of orbit with respect to it and Saturn has a pair of moons with horseshoe orbits with respect to each other.

[Petrochemicals (OP)]

It would affect the orbits of other planets and we would have noticed that effect (unless it was really small).
I suspect that some of our space telescopes would have seen it (again- unless it was really small), but it's fair to say that if he telescope was "near" Earth and given that we don't point telescopes at , or near, the Sun, we might have missed it unless one of the cameras looking at Mars or something spotted it.

most cameras and satelites are earth orentated as you say, and most probes do not come on line until at there destination like new horizons,? Pioneer ? Probe i think went to the inner planets, and had bad resolution and wasnt looking either

As in the 1969 film

https://m.imdb.com/title/tt0064519/

Is there a planet the other side of the sun that we cannot see ? Do we have visual confirmation. I will accept gravitational effects and orbital acceleration as conjecture

Also mods this is a serious question of physics, and its at least 49 years old so it is not a new theory.

It's a good question no matter how old it is. However a planet would cause perturbations of Mercury and Venus which would don't see.

The ossilations in there orbits are obviously missed and are factored into the standard orbits, any perbutations are hidden from view and not registered as the hidden planet. Also the smaller orbits of the inner planets mean the effect is less aparent

This is an old idea but such an orbit would be very unstable and could not last long.

It only needs to last as long as the civilisation of man

Its lasted

The point just opposite the Sun in Earth's orbit is Earth's  Lagrangian point #3
However unlike points 4 and 5, it is not fully stable.   An object put there would stay there only if it is left completely undisturbed. Think of it as a needle balanced on its point.  The slightest nudge of any kind and it will topple over.
Basically this would require the Solar system to be completely empty other than for the Sun, Earth and this object.   
 

Well perhaps thats why its so well hidden, an accumulation of different accelerations and alterations, keep the planet close enough behind the sun to hide it, keeping the needle balanced, or like the skick you balance on the end of your finger . I like the answer though, thanks.

[wolfekeeper]

It only needs to last as long as the civilisation of man

Nah. Having played with gravity simulation programs quite a bit I would guess it would last a few thousand years at most.

The problem is that if moves even slightly out of line with the Earth then the Earths gravity will pull it further away and it will slide off further away one way or the other. The Earths gravity is not all that strong at that distance, but it's not zero, and there's nothing fighting it; normally the gravitational pull of, say, mars cancels out over a whole orbit but this wouldn't cancel.

[Kryptid]

It only needs to last as long as the civilisation of man

It would have to have lasted for the approximately 4.5 billion years that the Solar System has existed in order for it make it to the era of human civilization in the first place.

[Janus]

It would affect the orbits of other planets and we would have noticed that effect (unless it was really small).

The ossilations in there orbits are obviously missed and are factored into the standard orbits, any perbutations are hidden from view and not registered as the hidden planet. Also the smaller orbits of the inner planets mean the effect is less aparen

It doesn't work that way.The perturbations caused by the other planets wouldn't be just oscillations, but long term and accumulative over time.

[jeffreyH]

There has been mention of the effect of the earth on the hidden planet but it would also have an effect on the earth. I think we would have noticed an anomaly in the orbit of our own planet.

[Bored chemist]

any perbutations are hidden from view

By what?

[evan_au]

See: https://en.wikipedia.org/wiki/Counter-Earth#Scientific_analysis

[Petrochemicals (OP)]

Could we not just be accrediting the gravitational effects to the sun,  there retrograde motions differ from planets slower and further from the sun ? The mass of the sun is calculated and is easily enough to be in error ?

Any variance of planets is hidden by the zun and theplanets motion is balanced by the acceleration on approach and the decelleration on leaving Just as is seen in other planetary interactions, all would be hidden by the large sun. It was only by seeing the gravitational effects of outer planets on known planets that planet x was hypothesised.

As for the timeframe a planet hidden the other side of the sun would only hav3 to be hidden for 3000 years.  Maybe its the long missing planet between earth and jupiter to make up the missing mass ?

[Janus]

Could we not just be accrediting the gravitational effects to the sun,  there retrograde motions differ from planets slower and further from the sun ? The mass of the sun is calculated and is easily enough to be in error ?

No.  Just adding extra mass to the Sun would not have the same effect as a planet opposite the Sun of the Earth. Adding mass to the sun would have a different effect on Mercury and Venus than adding a mass orbiting further from the Sun then they do. In addition, neither would you see the same effect on the how the orbits of the other planets would precess. 

Any variance of planets is hidden by the zun and theplanets motion is balanced by the acceleration on approach and the decelleration on leaving Just as is seen in other planetary interactions, all would be hidden by the large sun. It was only by seeing the gravitational effects of outer planets on known planets that planet x was hypothesised.

It's a lot more complicated than just an temporary acceleration and deceleration.

As for the timeframe a planet hidden the other side of the sun would only hav3 to be hidden for 3000 years.  Maybe its the long missing planet between earth and jupiter to make up the missing mass ?

The problem is that there is no way a planet could have started somewhere else, drifted into that position, stayed there for 3000 yrs and then drift away.

 Why are you so insistent on clinging to an idea that you've been told again and again isn't possible?

Besides, the Galileo probe trajectory eliminates any possibility of such a body existing.   In order to get to Jupiter is had to use several passes by both Venus and the Earth in order to get gravity assists.  This trajectory would have had it getting close enough to such a body for it to have a significant effect.   Using multiple gravity assists like this require the trajectory to be very precise. miss one fly-by by just a little amount and you'll find yourself not even coming close to the next one.   The fact that these series of passes happened just like they were supposed to means that there could not be anything orbiting on the opposite side of the Sun from the Earth.

[Petrochemicals (OP)]

The gravity assists of the voyager spacecraft required lots of adjustments, this is where most of its thruster fuel went, like directing itself toward its targets.

The solar studying spacecraft launched recently are stated as "should have seen" which does not sound very confiamational

The mass of the sun and the mass of jupiter, and there interactions have more than enough margain of error to allow for the existence of a hidden planet. The perturbations are of the type that revert and are there fore unseen.

Why do i keep asking ? Because i want a man in a rocket to go and see so i do not need to wrooy about aliens
 

[Kryptid]

As for the timeframe a planet hidden the other side of the sun would only hav3 to be hidden for 3000 years.

You forgot about the 4.5 billion-year thing I mentioned earlier?
 

Maybe its the long missing planet between earth and jupiter to make up the missing mass ?

What long-missing planet? What missing mass? You do realize that any planet between the Earth and Jupiter would, by definition, be further out from the Sun than the Earth and therefore would orbit at a different speed than the Earth? That would make it as visible as Mars and Jupiter since the Earth would catch up with and overtake it on a regular basis.

Why do i keep asking ? Because i want a man in a rocket to go and see so i do not need to wrooy about aliens.

Are you serious? The probability of a planet identical in mass to the Earth forming around the Sun at an identical distance from the Sun during the Solar System's formation and then remaining in a stable orbit for 4.5 billion years is extremely remote. Alternatively, the probably of a planet that formed elsewhere settling into an orbit exactly on the opposite side of the Sun from Earth is also extremely remote. On top of that, the probability of such a rogue planet having any degree of complex life is also remote because it would have suffered from extreme climate change from changing orbits.

[Petrochemicals (OP)]

3000 years would suffice to keep it hidden, besides if it is being kept on one side of the sun by gravitational forces, if it was showing either side of the sun it would most likely be mistaken for mercury or venus and not seen by many people due to its proximity to the sun. Maybe 1500AD is the date it needs to be hidden from.

https://www.universetoday.com/14869/was-there-a-planet-between-mars-and-jupiter/

As you say it could have migrated, just as jupiter is hypothesised to have done, but that is conjecture. I do agree with the gravitational attraction theory, but it is not scientific fact.

[Bored chemist]

Any variance of planets is hidden by the zun

No
That's not how orbits work.
We would track the motion of, for example, mercury and it would speed up + slow down as it was attracted to "planet x".

You seem to overlook the fact that gravity is a long range force.

[Kryptid]

3000 years would suffice to keep it hidden, besides if it is being kept on one side of the sun by gravitational forces,

So where do you propose that it was during the rest of its 4.5 billion-year life? What event would have occurred that would have allowed it to so conveniently slide into Earth's orbit on the opposite side of the Sun? There isn't any "counter-Mars", "counter-Mercury" or any other counter-planets, so why would the Earth be the strange exception?

if it was showing either side of the sun it would most likely be mistaken for mercury or venus and not seen by many people due to its proximity to the sun. Maybe 1500AD is the date it needs to be hidden from.

It would not move through the sky in the way that Mercury and Venus move, so that would give it away.

As you say it could have migrated, just as jupiter is hypothesised to have done, but that is conjecture. I do agree with the gravitational attraction theory, but it is not scientific fact.

Nor is a counter-Earth scientific fact. All evidence points against its existence.

[Petrochemicals (OP)]

Any variance of planets is hidden by the zun

No
That's not how orbits work.
We would track the motion of, for example, mercury and it would speed up + slow down as it was attracted to "planet x".

You seem to overlook the fact that gravity is a long range force.

Which would be hidden by the sun or  be travelling at an angle that would isguis3 the attraction, and that could be mis construed as variance in the orbit of the planet and attraction of the sun, perspective, cycles and wrongfully attributed gravity. The gravitational attraction could easily misplaced as the sun. It was easier tracking planet x as it wae outside the orbit of earth and variance was being viewed directly.

Kryptid, i propose it became thrown there by the migration of jupiter, formed in the gap between earth and jupiter, mars was one of its waywars satelites !

It would not be a wandering star maybe it would appear in the west about 2000 years ago ?


I do agree though computers are getting to the point that they may be precice enough soon to discern ine way or the other.