The fact we can see so far 'into' the comet, where its neck is, should suggest that it is not hollow. Are there any other theories that could explain it?
"Rosetta's instruments have already started sizing up 67P. They show that the comet is 4 kilometres across at its widest point and isn't very dense at all - in fact, its density is much lower than water ice. This means that 67P must be more than 60 per cent (sic) empty space.
Perhaps that means there are large caverns inside - cathedral-sized spaces that could burst open as the comet becomes more active.
"We just don't know yet", says Martin Patzold at the University of Cologne in Germany, It could be that the dust and gas is instead in a fluffy, loosely bound aggregate. "Whatever it is, it will help tell us how comets are formed. We really don't know that yet either," he says.
Quote from New Scientist article magazine (8 November 2014) - Just one shot at this parking spot
Hollow comets mystery
Could it be explained if comets are not ice mountains but rocky objects and gravity is electromagnetic in nature and in an Electric Universe?
Even a pile of course aggregate used as the base of road construction would have a far higher density than this, even though the pile would be full of air gaps.
Are there any thoughts as to how the structure of the comet could be so full of holes, it should look like a sponge.
When we look at large eroded areas like the striated side of the head, there is no clue to such a porous structure.
Its also difficult to imagine it being hollow, the erosion at the neck has been so extensive, it surely, by now, would have broken through to reveal a hollow core.
Also if the comet is built from interstellar dust, that is expected to be very fine, then you would expect it to pack very densely.
Baffled by these results ??
Comet 67P lighter than water ice?
If not hollow then the density of Comet 67P/C-G is very, very low - even for a dirty snowball. Scientific calculations based on their theories have Comet 67P/Churyumov-Gerasimenko with a density of 0.4 g/cm^3. Water density is around 1 g/cm3, ice density is 0.9167 gm/cm3 (vary with temperature). Magnesium solid is 1.7 gm/cm^3. Mineral soil density is around 2.7 g/cm3.
If it is not hollow then according to their theories it has to be of a material or aggregate that is very light.
So for Philae to succeed at landing, a soft surface will be preferable - something like a "snowdrift".
We're not sure what the strength of the surface materials is, but, if Philae encounters a consistency like "cigarette ash" or "champagne snow" - as some scientists have speculated - there's every hope it will become embedded in the surface.
Jonathan Amos - Looking ahead to the landing (bbc live blog)
If it is found to not be hollow and not made of ice or dusty material and is made of rock then this questions all those mainstream theories like the theory of Gravity, the Big Bang theory and Planet Formation theory?