Why Does Space If It Is So Cold?

Imagine standing outside on a freezing winter day. The air is cold because the molecules bump into your skin and steal your warmth. Space is like that winter day but even colder!

Space is mostly empty. There are very few gas particles to hold heat. On Earth, the sun warms the ground, and the ground warms the air above it. In space, there is no thick blanket of air to keep things warm. If you stand in direct sunlight, you feel hot because the sunlight hits you directly. But if you step into the shadow, you get very cold quickly.

Heat usually travels by touching other objects or moving through air. In space, heat escapes as light. Everything that has warmth sends out tiny beams of energy called radiation. Since space is empty, these beams fly off forever without stopping. This is why deep space is so cold, around -455 degrees Fahrenheit. It is the coldest place in our neighborhood!