# B Gravity and the sun?

1. Oct 27, 2017

### jayzun

The reason I made an account is to ask about the effect of gravity from an extra planet hiding behnd the sun. I think that if this was the case we would see much great impacts¿ say like the tides. Would they not be extremely high and low? Nonstop quakes that would be felt across the world? I asked this in a thread. Was advised to make a sperate thread.

2. Oct 27, 2017

### Staff: Mentor

The impact of a planet on the opposite side of our orbit would depend on its size, but would have to be pretty small; much smaller than the sun's impact on things like the tides, of course (since it would have to be much smaller and further away than the sun).

3. Oct 28, 2017

### Janus

Staff Emeritus
Tidal forces fall off by the cube of the distance. A planet hiding on the Other side of the Sun could not be much more massive than the Earth and would need to orbit at the same distance as the Earth. Since the Earth is ~1/333,000 as massive as the Sun, and the planet would be twice as far away as the Sun, its tidal effect on the Earth would be 1/8*1/333,000 = 1/2664000 that of the Sun.
It would be much easier to detect by its gravitational perturbing the orbits of the other planets. However, this is a two edged sword. They would also perturb its orbit. This is a problem because a planet orbiting on the exact opposite side of the Sun from the Earth is in a special type of orbit. It will only remain there if it stays exactly there. If it drifts the least bit out of position with respect to the Earth, gravitational forces will act to pull it even further out of position. It's like a needle balanced on its point; the slightest nudge and it topples over. Since such a planet could not help but be nudged out of position by the pull of other planets, it would soon drift into an orbit that would make it visible from the Earth.

4. Oct 28, 2017

### jayzun

Right. So if a rouge planet was to be on a path for us there would be NO way for any government to hide. The planet x doomsday people are out in left field,but entertaing.

5. Oct 28, 2017

### Staff: Mentor

You were asked to start a new thread to discuss gravitational effects, not pseudoscience and conspiracy theories. That is not allowed at the PF. Thread is closed.

(BTW, rouge = red)