I propose that Venus has a different composition from Earth, and this indicates that Super Earths with Earth-like surface gravities are imaginable :
My reasoning is elementary. Venus’ diameter is 600 kilometers less than Earth’s 12,650 kilometers. The volume of a ball is diameter to the power three, so Venus’ volume is 86% of Earth volume. Should Venus and Earth have similar compositions, Venus should therefore be 86% of Earth’s mass.
However, this is not the case: Venus is significantly lower than it should be..
Deviations of man-made probes zooming by showed that Venus’ mass is 81% of Earth’s mass.
Some Venusian mass is missing.
The mass discrepancy is all the more blatant, as Earth is full of water (down to depth 600 kilometers at least). Water is light: it has density 1 (one gram per cubic centimeter). So, if anything, Earth’s mantle should be lighter. Silicate rocks (which make most of Earth’s crust and mantle have density 3.
I propose this:”Venus is less massive because it does NOT have (as much as of) Earth’s heavy radioactive and nickel-iron core.
Indeed, what else? Uranium and the like have more than twice the density of iron (19.1 versus 7.8… g/cm^3). I believe Earth is in what I call the Radioactive Zone. Not just the Water Zone, aka the “Habitable Zone”. According to me, without radioactivity at the core, or a somewhat similar arrangement, indigenous life is not possible. It’s not just a question of avoiding many cosmic disasters… We need an enormous fission reactor inside…
Venus’ magnetic field is weak, and make the planet appear like a comet (observing with some instrumentation). Because the Venusian magnetosphere is weak, the solar wind shreds the Venusian upper atmosphere, in particular robbing it of hydrogen (water).
Recent studies of Mars show that the Martian atmosphere was shredded, and thrown to the stars by Coronal Mass Ejections (CME). CMEs do not affect Earth’s atmosphere, because the Solar Wind is deviated away from Earth’s sensitive atmosphere by the Earth’s mighty magnetic field.
Why is the Earth’s magnetic field so strong? Because we have a churning ocean of liquid iron below our feet. That churning in turn is caused by the extremely hot core. The surface of the core is as hot as the surface of our sun, Sol. If suddenly the ground became transparent, and we could see the core directly, we would be immediately blinded, and then roasted.
I have proposed, for several decades, that all this heat is caused by having a lot of radioactivity in the core. That’s what provides with the enormous energy needed. That used to be “scientifically false”, for no scientific reason that I could understand. I had heated arguments with at least one laureate of a Geophysics prize, about this (so heated, and in front of his wife, that he claimed later that the humiliation he suffered a particular day, contributed heavily to the failure of his marriage… Methinks it’s rather his hysteria which damaged his aura…).
Now neutrinos geophysics is a reality, though. Radioactive fission generate neutrinos. Those have been picked up from the core of the Earth, demonstrating my point in its full intensity. At least 50% of the Earth’s core heat is now known to be of radioactive origin. .
So Venus has a different composition from Earth, less heavy-duty, less of a heavy fission core to animate a mighty iron ocean churning inside, as demonstrated by its apparently nonexistent internally generated magnetic field (Venus has an externally generated magnetic field, showed ESA’s Venus Express). Actually Venus is the only of the major planets I know without a magnetic field. Thus, we may deduce that Super Earths, just like planets in our own solar system, may also have varying geological compositions.
Conclusion: As I will show in a separate essay, the composition of a Super Earth can be so full of silicates that the ground gravity is similar to Earth (elementary mathematics!). To believe that scaling up the composition of Earth to all and any Super-Earths is a necessary assumption is wrong. It is wrong, looking at Venus, just as it is wrong, looking at Mars.We have indication that the internal composition of rocky planets vary tremendously.
Considering that Super Earths are the most frequent type of planets found (so far; partially an experimental quirk…), there will be habitable Super Earths. Build very much bigger telescopes, pretty please…