https://www.youtube.com/watch?v=gnZVvYm6KKM

This shows the relative sizes of the orbits and planets in the multi-transiting planetary systems discovered by Kepler up to Nov. 2013. The colors simply go by order from the star (the most colorful is the 7-planet system KOI-351). The terrestrial planets of the Solar System are shown in gray.

Everytime I go shopping for engines I go looking for orrerys. Not found a nice brass one yet in the five to six hundred buck mark.

AwesomeO said:

Everytime I go shopping for engines I go looking for orrerys. Not found a nice brass one yet in the five to six hundred buck mark.

Surely someone of your skills could make one

JudgeMental said:

https://www.youtube.com/watch?v=gnZVvYm6KKM

This shows the relative sizes of the orbits and planets in the multi-transiting planetary systems discovered by Kepler up to Nov. 2013. The colors simply go by order from the star (the most colorful is the 7-planet system KOI-351). The terrestrial planets of the Solar System are shown in gray.

Thanks for posting this. It also appeared on the TV Program “Secrets of the Solar System” last night.

My first thought on seeing this was “fake”, although on reflection it’s the best we know. All orbits are displayed as circular, whereas variations in orbits of binary stars from Kepler show that most are highly elliptical, some extremely elliptical. In the absence of further data, I’d assume that the ellipticity of planetary orbits is the same as that of binary stars. However, although the ellipticity of binary stars observed by Kepler is known (or able to the be approximately estimated), that of planets can’t be accurately estimated. Despite a recent paper on ArXiv that explains a way to do precisely that. I’ve already tried to do that. Further on the Kepler Orrery, there’s a simple demonstrable error in the image – look at the largest planets. There are less than half a dozen huge ones, and the largest is much larger than the second largest, larger than the third largest etc. Wrong, wrong wrong. Anything more than 40% larger than Jupiter is a star, so all the largest planets (including brown dwarfs) on the Orrery ought to all be the same size, the size of Jupiter. So somebody has made a slip-up and included binary stars in with the planets in the Orrery.

The important point from the Kepler Orrery is that our Solar system in no way resembles ANY of the planetary systems found by Kepler. Prior to the discovery of exoplanets, astronomers looked for ways to explain why our solar system was the only type of solar system that could exist. But … etc.

I strongly disliked many of the statements made in the TV program “Secrets of the Solar System”. For instance, I agree that Jupiter could have migrated inwards due to gas drag, that’s a given. I do not agree that Jupiter coming into resonance with Saturn could have made Jupiter migrate outwards, nor do I agree that after coming into resonance Jupiter and Saturn could have lost that resonance. So Jupiter never came closer to the Sun than it is now, and the inner rocky planets formed quite independently of any influence from Jupiter, which has been shown by mathematical modelling anyway.

I also cringed every time the program “Secrets of the Solar System” referred to “hot Jupiters” as gas giants. Hot Jupiters are not gas giants, most of them are brown dwarfs, and the others would be rock-dominated not gas and ice dominated.

I do know why such weird and wacky theories for planetary formation as shown on the TV program came into being. For a very long time astronomers have known that mathematical models of planet formation do not explain where Neptune and Uranus came from, and give a mass too small for Saturn. As a result, astrophysicists have come up with the idea that Uranus and Neptune (and possibly Saturn) formed much closer to the Sun and migrated outwards under the gravitational influence of Jupiter. That’s OK, but it doesn’t explain how four gas giants initially formed in the same place. It also doesn’t explain why Jupiter is outside the “ice line” explained in the program. I’m more inclined to look for other possibilities, two that immediately come to mind are that the mathematical models had underestimated the concentration of gas and dust out near the orbits of Uranus and Neptune, and that mathematical models do not take into account variations in solar brightness when the giant planets were forming.

The inward movement of large planets has been used to explain hot Jupiters in other solar systems. I consider that as just one of two alternative explanations – the other explanation would be that the angular momentum of the infalling gas cloud that formed the star was too large for the formation of a single body, and that conditions of angular momentum dictated that the system resolve into a binary or multiple star system – if the binary or multiple component was small enough it would be called a planet.

> All orbits are displayed as circular, whereas variations in orbits of binary stars from Kepler show that most are highly elliptical, some extremely elliptical. In the absence of further data, I’d assume that the ellipticity of planetary orbits is the same as that of binary stars. However, although the ellipticity of binary stars observed by Kepler is known (or able to the be approximately estimated), that of planets can’t be accurately estimated.

Brand new ArXiv paper from Dec 2014. Of 50 Hot Jupiter exoplanets studied, 27 had either eccentric orbits or orbits at a steep angle to the star’s equator. 23 had circular orbits aligned with the star’s equator. That ratio is not shown on the Orrery where all orbits are shown circular. There are other problems with it as well, for example the system at lower right is only consistent with a central star with a mass less than that of Neptune, impossible.

I hope you’ve noted that only the inner four rocky planets are shown on the Orrery for the Solar System. Jupiter would be way out of the frame.