Except if it was a 6-Earth-mass hamburger, gravity would immediately pull it into a sphere, the heat would melt it, it would differentiate, the metals from the meat going to the center to form a very tiny core. The main elements would be oxygen, carbon, hydrogen & nitrogen.../1 https://twitter.com/nytscience/status/1304613716583997440

2/...in that order. They would form carbon dioxide (30.1%), water (45.5%), and methane (31.7%). There would be 1% nitrogen. Like Pluto the nitrogen would be in the atmosphere and surface ice. Maybe nitrogen glaciers would glow, like on Pluto!

3/ This “hamburger” would be quite hot, since it collapsed into a sphere all at once. Doubtless it would have liquid water oceans in the mantle. It would likely have a methane atmosphere like a Titan, but thicker with higher pressure since this is a 5-Earth mass burger.

4/ The heat and pressure would likely keep some methane liquid at the surface, like the lakes of Titan.

5/ There was a recent study arguing that Pluto kept its liquid subsurface ocean because it formed quickly before the heat could all radiate away from the surface. The gravitationally rounded burger would be even hotter. https://news.ucsc.edu/2020/06/pluto-ocean.html

6/ With all that water, methane, and CO2, plus so much energy, there would be cryovolcanism recycling materials between the mantle and the crust, like on Europa. The crust would develop interesting geological features as the materials move around. What an amazing hamburger!

7/ The energy would also rework the chemistry of these ices. It would create tholins — complicated chain and cyclic molecules, the building blocks of life. Of course the hamburger started out as organic matter, but a fraction would become organic matter again. Chemistry happens!

8/ Some day we can visit this gravitationally processed hamburger. Will there be life swimming in its subsurface oceans? Will there be intelligent being living on its crust, or flying to the top of the brown hazy atmosphere to get a peek at the stars? ( https://www.sciencemag.org/news/2016/12/alien-life-could-thrive-clouds-failed-stars)

9/ Will the thick atmosphere have storms that weather the crustal materials into small grains, forming vast dune fields like on Mars? (Will there be sand worms?)

10/ Will mountains of ice form (like on Pluto), then weather away, and form again? ( https://www.bbc.com/news/science-environment-33543383)

11/ This burger had plenty of hydrogen to begin with, so maybe like Uranus and Neptune there will be liquid metal hydrogen deep down near its tiny core, creating a dynamo to form a magnetic field. ( https://svs.gsfc.nasa.gov/4666 )

12/ My point is that a 5-Earth-mass hamburger is indistinguishable from a planet. That’s the cool thing about planets: just by being big enough to be gravitationally rounded, but not so big that fusion begins (releasing a flux of energy that wipes out much of the diversity)...

13/ ...just by being in that sweet spot of size, an amazing engine of complexity turns on. Planets constitute a tiny fraction of the mass of the cosmos, but the most interesting stuff in all the cosmos happens there! Even a big enough hamburger would have this result.

14/ We know so much more about it now than Galileo did, but this was precisely the insight Galileo had when his telescope revealed mountains on the Moon. He realized it is “another Earth”, & since the Moon is a planet, so all the planets are complex geological bodies like Earth.

15/ And this is really what the concept of a planet is. It is about the sweet spot of nature where complexity turns on, where geology and chemistry come alive, where life might sometimes exist. Planets are diverse, but this is their common core.

16/16 By the way, I couldn’t find the elemental composition of a hamburger so I focused on just the patty. I couldn’t find that, so I used a cow. I couldn’t find that either, so I used a human. I found that! So in realty, this is the planet you’d get from a 5-Earth-mass human