At what distance would binary planets not be tidally locked?

AI Thread Summary
The discussion centers on the feasibility of binary planets being tidally locked while orbiting a common barycenter. It is established that the distance of 702,904.853 km is sufficient for the planets to rotate independently, as tidal locking is influenced more by the age of the system than by distance. The planets could potentially rotate at different rates, with one possibly being synchronized while the other is not. The gravitational effects are similar to those experienced between the Earth and its moon, suggesting that tidal interactions would be significant. Overall, for storytelling purposes, the setup is plausible without needing to adhere strictly to hard science.
Hainted
Messages
3
Reaction score
0
Working on a story idea that involves binary worlds. To keep the math simple I'm assuming the planets to be Earth sized, and mass, orbiting a star identical to the sun. I managed to find someone to help with the first equations and discovered that based on the time it takes them to orbit each other (48 days) they would be 702,904.853km apart, and based on their year (432 days) they are 167,323,260km or 1.1 AU from the sun. I also discovered that a full "moon" would be 8 times brighter than our moon.

My question is Would 702,904.853km be far enough apart for them to rotate, or would they be tidally locked? Is it even possible for them to rotate and still be orbiting a common barycenter, and if so what would the distance be?

FYI I don't need the equations( I'm 2 decades out of school) but I don't need it explained like a 5yo either. Just looking at plausibility of this.
 
Astronomy news on Phys.org
Hainted said:
Is it even possible for them to rotate and still be orbiting a common barycenter, and if so what would the distance be?

Yes, it is possible. What matters is not the distance but the age of the system; the tidal lock develops over time. So for story purposes, you can have it however you want :smile:.
 
Thanks, I'm not doing Hard SF, but I want to avoid making a complete fool of myself scientifically.
 
Yes I would say it would be probable that the worlds would rotate, but still may be synchronized if the system is very old.
Your distance is nearly twice the Earth moon distance of 384,400 km, but an Earth mass is roughly a little more than 8 times a moon mass, and since tides are raised to the cube of the distance, the tides on each world would be nearly the same (slightly more) as the moon raises on the earth.

You could still have the worlds rotate at different rates, or even make one world a little smaller and say it is synchronous and the larger one is not. About the only thing to watch out for is that smaller worlds are more likely to be synchronized by larger worlds.
 
Synchronized as in Same rotation period (I.E. 24 hour day) or synchronized as in one orbit(48 days) equals one day/night period?
 
Publication: Redox-driven mineral and organic associations in Jezero Crater, Mars Article: NASA Says Mars Rover Discovered Potential Biosignature Last Year Press conference The ~100 authors don't find a good way this could have formed without life, but also can't rule it out. Now that they have shared their findings with the larger community someone else might find an explanation - or maybe it was actually made by life.
TL;DR Summary: In 3 years, the Square Kilometre Array (SKA) telescope (or rather, a system of telescopes) should be put into operation. In case of failure to detect alien signals, it will further expand the radius of the so-called silence (or rather, radio silence) of the Universe. Is there any sense in this or is blissful ignorance better? In 3 years, the Square Kilometre Array (SKA) telescope (or rather, a system of telescopes) should be put into operation. In case of failure to detect...
Thread 'Could gamma-ray bursts have an intragalactic origin?'
This is indirectly evidenced by a map of the distribution of gamma-ray bursts in the night sky, made in the form of an elongated globe. And also the weakening of gamma radiation by the disk and the center of the Milky Way, which leads to anisotropy in the possibilities of observing gamma-ray bursts. My line of reasoning is as follows: 1. Gamma radiation should be absorbed to some extent by dust and other components of the interstellar medium. As a result, with an extragalactic origin, fewer...
Back
Top