While Titan, Saturn's largest moon, does have an atmosphere and lakes composed partially of methane, it does not ignite and become a star-like object for a few reasons:
Lack of Oxygen: For combustion to occur, a fuel source (such as methane) and an oxidizer (usually oxygen) are required. While methane is flammable and can burn in the presence of oxygen, Titan's atmosphere is predominantly composed of nitrogen, with only trace amounts of oxygen. The lack of significant oxygen concentrations prevents sustained combustion.
Insufficient Energy: Combustion also requires an ignition source or an energy input to initiate the reaction. On Earth, we typically use sparks, flames, or high temperatures to ignite flammable gases. However, Titan's environment lacks the necessary energy sources to initiate or sustain combustion on a large scale.
Low Temperature: Titan's surface temperature averages around -290 degrees Fahrenheit (-179 degrees Celsius). Such extremely cold temperatures limit the mobility and reactivity of molecules. The low temperatures on Titan make it difficult for methane to achieve the activation energy required for combustion to occur.
While methane can burn in the presence of oxygen and a source of ignition, the conditions on Titan, such as the lack of oxygen, insufficient energy, and low temperatures, prevent it from spontaneously igniting and becoming a star-like object.