Mercury

Space/Science » in reply to re: Massive solar tides

Mercury

nick hoffman — 4/25/2007 10:50:38 PM (archived)

One of the interesting things about Mercury's orbit is that is is extremely oblate (elliptical). This allowed Einstein to base a fundamental test of Relativity on the evolution of Mercury's orbit - it's precession.

It also means that the tidal effects on Mercury conspire to produce a near-synchronicity of its orbital rate and rotation rate WHEN IT IS CLOSER TO THE SUN.

Tidal effects vary as 1/R^3, so it is in the closest parts of the orbit that tides are strongest.

Note that this implies a very long-term stability of the oblateness of mercury's orbit.

The whole thread (70 posts)

Earth-like planet, with water, around red dwarf Gliese 581? - REB - 4/24/2007 7:31:46 PM
- Are we *sure* it'd have volatiles? - dtb - 4/26/2007 1:13:42 PM
  - No such thing as sure - nick hoffman - 4/26/2007 11:37:36 PM
- It's actually has a diameter 50% larger than our world. - Jacob Samorodin - 4/25/2007 11:16:43 PM
  - re: Would the absense of a magnetic field be as catastrophic to the atmosphere of a red-dwarf planetary system? - The Artist formerly known as Scott Evil - 4/26/2007 3:15:47 AM
    - Solar wind - nick hoffman - 4/26/2007 9:53:47 AM
      - re: Solar wind - Joe P. - 4/26/2007 4:49:47 PM
        
        "day" and "year" - nick hoffman - 4/26/2007 11:47:47 PM
      - very interesting... Now we need a imaging telescope that can tell us more! - The Artist formerly known as Scott Evil - 4/26/2007 1:40:37 PM
- re: The discoverer - Raoul - 4/25/2007 6:24:36 AM
- Two interesting facts... - TB - 4/25/2007 6:12:00 AM
- Couple of questions: - TB - 4/25/2007 5:46:25 AM
  - re: Couple of questions: - REB - 4/25/2007 1:37:28 PM
    - Splitting Hairs - 3 days per 2 years - M.A.E. - 4/25/2007 9:06:37 PM
      - Who needs an atmosphere? - nick hoffman - 4/25/2007 11:10:46 PM
        
        Good point but - M.A.E. - 4/26/2007 2:31:25 AM
        
        re: Good point but - Excellent points by both of you (MAE & Nick). - Marcia - 4/26/2007 8:44:42 PM
    - re: Couple of questions: - Raoul - 4/25/2007 2:15:50 PM
      - Did some digging. maybe this will help. - REB - 4/25/2007 2:30:44 PM
        
        re: Did some digging. maybe this will help. Thanks, REB. - Marcia - 4/26/2007 2:03:16 PM
        
        Speaking of a moon- could part of this planet's calculated mass be a moon? - REB - 4/26/2007 2:34:40 PM
        
        Not 4 Earth masses- 5 Earth masses. - REB - 4/26/2007 2:57:26 PM
        
        I would love to see a true binary-planet... Where two relatively equal planets are sharing the same center of gravity. - The Artist formerly known as Scott Evil - 4/26/2007 4:25:03 PM
        
        I wonder what it would have been like to have Venus as our moon. - REB - 4/26/2007 9:57:49 PM
        
        Very Good point! - The Artist formerly known as Scott Evil - 4/26/2007 2:50:57 PM
        
        Good detective work. You were correct! - ER - 4/25/2007 3:13:11 PM
      - re: Couple of questions: - REB - 4/25/2007 2:22:58 PM
  - re: Couple of questions: - ER - 4/25/2007 11:19:37 AM
    - re: The flares could themselves result in "seasons" on such a planet. - The Artist formerly known as Scott Evil - 4/25/2007 2:44:07 PM
      - Interesting... - nick hoffman - 4/25/2007 11:07:18 PM
        
        I've always thought of seasonality as being critical to drive evolution. - The Artist formerly known as Scott Evil - 4/26/2007 3:26:56 AM
        
        re: I've always thought of seasonality as being critical to drive evolution. - Joe P. - 4/26/2007 4:55:37 PM
        
        Interesting idea, I've started a new thread on it, I hope you don't mind. (n/t) - ER - 4/26/2007 2:36:15 PM
        
        Not at all. - The Artist formerly known as Scott Evil - 4/26/2007 2:53:31 PM
        
        Well Evolution Requires Either Genetic Drift Or Selective Pressure - M.A.E. - 4/26/2007 2:07:13 PM
        
        Getting wiped out can be good for evolution. - The Artist formerly known as Scott Evil - 4/26/2007 4:40:25 PM
      - Donâ€™t Red Dwarfs flair when they are young and calm down as they get older? - REB - 4/25/2007 2:48:57 PM
        
        Flares last minutes, maybe an hour or so (n/t) - phil - 4/25/2007 2:52:33 PM
        
        I mean a Red Dwarfâ€™s Flare frequency goes decreases as the star ages. - REB - 4/25/2007 2:55:23 PM
        
        rI'm specificly referring to red dwarf flare times (n/t) - phil - 4/25/2007 2:59:20 PM
  - Found a few answers - TB - 4/25/2007 6:13:19 AM
    - Also, what about moons, double planets - Sawyer - 4/25/2007 1:10:56 PM
      - Massive solar tides - ER - 4/25/2007 1:37:21 PM
        
        Tides - phil - 4/25/2007 2:58:39 PM
        
        Not sure about that... - TB - 4/25/2007 2:34:07 PM
        
        I think it would depend on the specific make-up of the planet and it's atmosphere (if any) - The Artist formerly known as Scott Evil - 4/25/2007 2:46:52 PM
        
        You're right about the tides, senior moment on my part. - ER - 4/25/2007 2:44:57 PM
        
        Don't be too hard on yourself - TB - 4/25/2007 4:25:37 PM
        
        re: You're right about the tides, senior moment on my part. - REB - 4/25/2007 2:57:21 PM
        
        re: Massive solar tides - REB - 4/25/2007 1:51:15 PM
        
        re: Massive solar tides - ER - 4/25/2007 3:09:29 PM
        
        Mercury - nick hoffman - 4/25/2007 10:50:38 PM
- Well, that's not fair... - TB - 4/25/2007 5:44:30 AM
- Data on this Star (from 2nd Gleise Catalog) - ER - 4/25/2007 12:03:02 AM
- Wow! - Peter Bruener - 4/24/2007 9:28:05 PM
  - re: Wow! - Raoul - 4/24/2007 9:41:52 PM
  - I got the size wrong. This planet is 50% larger than the Earth. - REB - 4/24/2007 9:38:30 PM
    - 2.2Gs at 5 Earth masses and 1.5 Earth radii - phil - 4/24/2007 9:50:09 PM
      - Thanks Phil - Peter Bruener - 4/25/2007 5:03:02 AM
        
        AP says 1.6G; I don't get it (n/t) - phil - 4/25/2007 4:01:24 PM
        
        Either way it would be a great place to train athletes (n/t) - FrankC - 4/26/2007 9:43:21 PM
        
        That seems high. Jupiter is something like 2.3-2.4 with over 300 times the mass of Earth. (n/t) - REB - 4/25/2007 4:17:52 PM
        
        Huge Difference In Density - M.A.E. - 4/25/2007 9:27:29 PM
        
        How do they know the radius? - ER - 4/25/2007 10:30:48 PM
        
        They Don't - M.A.E. - 4/26/2007 2:17:47 AM
        
        Radius - depends on density which depends on compositionj which depends on.... - n - 4/25/2007 11:24:02 PM
        
        A relevant paper online... - Adam - 4/27/2007 2:04:02 PM
        
        re: That seems high. Jupiter is something like 2.3-2.4 with over 300 times the mass of Earth. - ER - 4/25/2007 4:59:18 PM
- re: ESO discovery ! - Raoul - 4/24/2007 8:50:06 PM
  - D'oh! 50% larger than the Earth, not smaller. - REB - 4/24/2007 8:57:43 PM

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