7 new Worlds

The big science news this week was the discovery by NASA scientists of a planetary system with Seven Terrestrial planets in it and three in the habitable zone.  How timely, after me posting so recently about how planets close to their star might look like.  Seven Earth-like sized planets.  Around a star that is a small fraction of the size of our own.  These planets are close to each other too, they probably have some interesting resonances.  These are the planets and their orbital lengths in Earth Days:

b 1.51

c  2.42

d 4.05

e 6.10

f 9.21

g 12.35

These are the ratios in the orbital periods, between the next closest planet:

1.6

1.67

1.51

1.51

1.34

This is interesting.  The close moons of Jupiter have a more defined resonance.  The first three moons of Jupiter have an orbital resonance of 2:1 between the one closer to Jupiter. 

Here are the orbital ratios in terms of the first planet:

1.6:1

2.7:1

4:1

6:1

9:1

It looks like ere is something wrong with these orbits.  I strongly suspect that they are going to get better data and alter the findings from this system, but to be clear, this is the data they have observed and with the best instruments available.  There is not proof that the planets are as observed, but this is what has been observed, so it is observed fact.  We are after all looking at a system that is 40 light years away and we are not observing the planets directly either; we are observing the dimming of the light from the star as the planets pass before it.  There could be another planet that is causing more dimming out further away in a more distant orbit.

One thing that the observers were able to calculate was the orbital distance from the star and the masses of the planets.  

Earth Masses:

b 0.9  

c 1.4

d 0.4

e 0.6

f 0.68

g 1.3

Distance from Star in AU, distance from each other in fractions of the Earth-Moon distance:

b 0.011

c 0.015. 2x

d 0.021.  3x

e 0.028. 3.5x

f 0.037.  4.5x

g 0.045.  4x

The moon is about 385,000 km away.  And the ratio of the masses is about 6:1 and on earth this means we get tides without doing the math I can see that there would be a subtle effect on these planets with each other.  The moon is locked with one face always towards us after all in addition to the tides.  

The scientist were fairly certain that the planets were tidally locked, but I think they made an improper guess that the planets were fixed with one side facing the star.  The eccentricity of the orbits has been pegged as very little deviation.  They might have greater eccentricity and this would affect their orbit.  Mercury is not locked in the same way as the moon is to the Earth.  The moon's day to year is 1:1 and Mercury it is 1.5:1.  There could be this sort of resonance in these planets— point in fact, the orbital ratios might mean that the planets have not settled into such a stable pattern, they could be suffering from days that are shorter than their years.

The really big news will come when we get more precise measuring instruments and we can measure the temperature of the night side of the planets and the atmospheres of these planets.  It is possible.  These planets are way too inaccessible to get there except with science fiction.  40 light years is so far that we would have to bankrupt the economy of the planet just to send a tiny satellite there, which would still take 400 to a thousand years to get there.

Remember, we have a planet perfect for life right here, take care of it, it is all we have.