Stars are massive, luminous spheres of plasma primarily composed of hydrogen and helium that generate energy through nuclear fusion. The core temperatures of stars are incredibly high, reaching millions of degrees Celsius. Therefore, by definition, stars are hot and emit various forms of electromagnetic radiation, including visible light, which is what makes them visible to us.
Cold objects, on the other hand, generally do not emit visible light. When we observe an object in the sky and perceive it as "cold," it is typically because it reflects or scatters the light from a nearby source, such as the Sun or another star.
However, it's worth noting that not all stars have the same surface temperature. Stars come in various temperature ranges, which determine their color and the type of light they emit. For example, blue stars are hotter than yellow or red stars. So while stars can have different temperatures, they are all still considered to be hot in comparison to objects we perceive as cold.
If you are referring to objects in space that appear cold due to low temperature, you might be thinking of celestial bodies like planets, moons, asteroids, or comets. These objects do not generate their own light but reflect or scatter the sunlight that reaches them, resulting in various temperatures depending on their proximity to a heat source, such as a star.
In summary, stars, by definition, are hot objects that emit light and heat due to the nuclear fusion processes occurring within their cores. Cold objects in space, like planets, do not produce their own light but reflect or scatter light from a nearby star, making them appear cold to us.