 Because giant planets don't burn hydrogen, brown dwarfs have more in common with them than they do with stars. To understand how we distinguish a brown dwarf from a low-mass star or from a high-mass planet, we'll examine the effects of increasing mass on celestial objects, starting with rocks. A rock maintains its shape and size due to the molecular bonding of its material. He plays no role in the size or shape of the object. An asteroid like Steins is a good example of this. As we increase the mass of an object, the first transition is reached when the mass produces a gravitational force strong enough to hold together a rubble pile. The near-Earth rubble pile asteroid Itacala is a good example of this. It contains a number of objects with different densities. As we continue to add mass, the force of gravity will at some point exceed the material strength of the body and force the object to take a more spherical shape. For materials with the strength and density of stony asteroids, the critical mass is around 580,000 trillion metric tons. Series is a good example of this. While becoming spherical is perhaps the most obvious outward sign of increasing mass, the interior of the body begins to undergo geophysical transitions as the mass increases. One is the transition to bodies large enough to sustain convection in their interiors. Convection is the process by which less dense material rises and more dense material sinks. Solid matter convection activates somewhere around 14 million trillion metric tons. An Earth convection in the mantle creates tectonic plate movement. We'll use Earth as our first baseline. Since solar systems are made up mostly of hydrogen and helium, there is insufficient solid matter to create terrestrial planets much larger than the Earth. There isn't another significant qualitative change in the relationship between pressure and gravity until we reach masses greater than 11 times the mass of the Earth. So we'll switch to giant gas planets like Neptune. It's 17 times more massive than the Earth, but almost 60 times larger. Its core is less dense and cooler, but it has more than twice the pressure.