# Could the earth's atmosphere have been partially stripped by a passing rogue planet?

I am involved in the fight between palaeontologists and aerodynamicists on the theoretical flight capabilities of the largest pterosaurs (who reached their climax in the Cretaceous and then disappeared at the K/T extinction event).

Is it possible that the earth's atmosphere was reduced at this time by a passing rogue planet or other sufficiently large body?

If so, the atmosphere would have been thicker.

Using the principle of Occam's razor, this one single hypothesis solves the problem of flight in the Mesozoic; the problem of how the dinosaurs could carry such weight; why they all had tails that would be much more use in a thick medium such as water...

The K/T extinction has attracted too many theories about what was 'added' to life on earth such as the comet/asteroid/Deccan Traps theories etc. No-one has looked at what might have been taken away from earth to cause the same effect!

If the earth's atmosphere had been much thicker (far higher pressure/density at the surface) the dinosaurs would have had a much easier time. Losing a huge amount of their atmosphere would kill them off because their 'effective weight' would have been doubled almost overnight.

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Though this is definitely an interesting question, I have to say that it seems to be more of an Earth sciences question than an Astronomy question. (which would make it off-topic) –  Donald.McLean Jan 12 '14 at 6:53
Though the question as phrased in the body seems too Earth-centric, the question as phrased in the title does seem on-topic: it significantly involves another astronomical body besides Earth. I would suggest rephrasing the body to focus on the rogue planet atmosphere stripping aspect. –  called2voyage Jan 13 '14 at 16:09
Since the OP hasn't come back in a while, I took the liberty of reframing the question around the part relevant to the Astronomy site. –  called2voyage Jan 15 '14 at 15:52

Very interesting question. I'm okay with this question being here since you specifically ask for the effect of rogue planets on Earth's atmosphere. Thinking "astronomically" could be useful in coming to conclusions about whether or not your idea is even a possibility.

When I saw this I instantly thought of ice cores, since trapped gas bubbles could tell you about the composition of the atmosphere. Unfortunately ice cores go nowhere near that far back to be able to tell you about the composition of the atmosphere during the Mesozoic.

• As far as rogue planets are concerned, I would find it rather unlikely that such a massive object would still be lurking around the solar system between about 252 to 66 million years ago. The early solar system was certainly more chaotic than it is now (for example, Giant impact hypothesis: $\sim 4.5$ Gya; the collision which caused Uranus' tilt: a few billion years ago), however it is not out of the realm of possibility.