What are the top ten tallest mountains in the solar system?  You might be suprised to find out that Mount Everest is not even on the list.

http://blogs.smithsonianmag.com/science/2012/01/the-tallest-mountains-in-the-solar-system/

Cool. I didn't expect earth to squeak into the list. I knew Everest was the highest on earth and not the tallest but often forget whether Mauna Loa or Mauna Kea is the tallest. Perhaps I'll remember now.

Yeah Scott, Earth barely squeaked in there.  The winner is Olympus Mons which is over 15 miles tall and its base is roughly the size of the state of Arizona.  Holy Moly!

One thing..
Understand that this is for Surfaces we can see...

One thing..
Understand that this is for Surfaces we can see...

True, but I would add that it seems unlikely that some as yet unknown Kuiper Belt object will have a bigger mountain. After all, they're basically big ice balls. I have no objection to calling any such object large enough to be round under it's own gravity and as the primary object in its orbit a planet, and would have left Pluto being called one, but still doubt they are likely to have really big mountains. And, this did say it was a list of largest mountains in our solar system.

I was referring to our gas giants..
we have 3-4 LARGE planets in our system, that we cant see the surfaces of.

YEP,
THERES SOMETHING INSIDE, AND WE dont KNOW WHATS HOLDING IT ALL TOGETHER.

YEP,
THERES SOMETHING INSIDE, AND WE dont KNOW WHATS HOLDING IT ALL TOGETHER.

I think the answer is that, to the best of our current knowledge, it's gas all the way down, though of course it gets denser as you go down. As for what holds it together, of course we know. It's gravity.

The gas giants formed the way stars form. Clouds of gas coalesce due to gravitational attraction. In the case of stars, they reach critical mass and begin to have nuclear reactions that build heavier molecules via nuclear fusion. Gas giants are basically just failed stars.

Now, in the case of our solar system, our sun is at least a second generation star. The gas cloud from which our planetary system formed had been a cloud from a supernova, which is how we have heavy elements on our planet, i.e. any element heavier than lithium. Even lithium was in extremely small quantities after the big bang. Most of the ordinary matter of the universe is still hydrogen and helium, the two main elements from the big bang. Places like earth that have heavier elements were formed out of the remnants of the supernova of the stars that created the heavy elements.

So, since there were heavy elements in the gas cloud from which our solar system was formed, it is possible that some ended up in the gas giants. However, the possibility of a large core of rock isn't indicated by the pages I read on the subject. So, I think it's not a bad thing to add a caveat that these are the 10 largest mountains of which we are aware in our solar system. But, it's also likely that the caveat is unnecessary.

and still,
we dont know whats in there...
I thought we landed(for a few seconds) on something on/in saturn.

and still,
we dont know whats in there...
I thought we landed(for a few seconds) on something on/in saturn.

Cassini, on Titan. Lovely movie of the descent available on line. Every so often i watch it again.