The sun warms up our planet but space is cold. If I lit a candle and stood 20 feet away, I could see the light but not feel the warmth. So, why do we feel warmth from the sun but space isn’t warmed by it?
In: 512
**Pretty much every comment is absolutely wrong.** The temperature of space is around 2.7 degrees kelvin (2.7c above absolute zero) which can be measured by looking at the cosmic microwave background radiation, which is light that was released as soon as the universe because transparent to photons.
This light is pretty much perfectly uniform in any direction you look, so even if you have a region of space with “nothing” in it, there is still microwave light from the big bang floating around.
**Why is it cold?** Because that light has been stretched over the past ~14 billion years. When the light was originally created, it was extremely energetic, but as the universe has expanded in size, the light has been stretched into microwaves. It is the same effect that causes sirens to change in pitch as the move towards/away from you.
Heat is a measure of the motion of particles. Less particles means less heat, anything close enough and facing the sun gets very hot. Between all the stuff in space, there isn’t much of anything, so there’s nothing to heat up.
There are different ways of warming things.
1. You can blow hot air on it like a convection oven or the HVAC system in your house.
2. You can shine a bright light on it like the hot lights that keep your food warm at a restaurant.
The sun is using option number 2 because there isn’t air in space, and even if there were, the sun is too far away. This is why it’s cooler in the shade on a hot day.
IN space, heat is transfered by electromagnetic radition including UV rays. A candle 20 feet awat wont produce enough EMR to warm you. When there is no EMR, you will freeze.
A lot of things in space are hot. A spec of space dust can be a few thousand degrees. However the spec of dust is nothing in comparison to the amount of space that is simply empty. Being that empty space holds no heat, it seems cold. Add in the fact that most organic matter released into space will have its water content rapidly and often violently become water vapor and it looks different. The water vapor escaping pulls in a tiny big of heat to make the change, cooling the rest of the object it left behind. Enough vapor exiting an object can freeze it solid, making it appear space is cold. However if they object is in direct star light, it will eventually heat up to some very high temperatures. Once the water has all vaporized, there will be fewer ways to cool down this chunk of matter.
Asteroids and such are usually far away from stars, and when they get close have a habit if creating water vapor trails (at least if they contain ice).
We don’t get heat from the sun, we get light. Visible light hits the Earth and heats it, and then the Earth heats the air. That’s why there can be snow on top of mountains when it’s hot at the base, even though mountaintops are closer to the sun. The turnaround time for all that happening also explains why the hottest part of the day is around 2 in the afternoon, not noon, and the hottest part of the summer is usually late July/August, not June 21 (the solstice).
Because there isn’t much there to warm up.
Even so, the temperature of space doesn’t matter all that much since there so little conduction involved and no convection. Compare standing in cold air vs jumping into a pool of cold water. Being more dense, the water is a much better conductor of heat and you feel colder much faster. This is actually a problem in space, as it is much harder to cool down sensitive electronics.
Space is empty.
So very, very empty.
One star you see in the sky, might just be the light of an entire galaxy.
Space is unfathomably big.
Space is unfathomably empty
Because entropy is a thing that exists
There will never be enough energy to heat up the universe.
At Noon on Mars, it can reach only as high as 20 degrees, or 70ish f, and mars aint all that far from the sun compared to the other planets, and then there is the fact that there is usually a light year or two between each star, and there between there is nothing to collect or store it.
It’s not hot, but it’s not really cold either. Temperature refers to the average speed of molecular movement in a sample of some kind of matter. No molecules (or almost none), no measurable temperature.
You might be able to sense the “heat” from the candle, because it emits radiant energy that can travel through a vacuum.
Heat is basically just a measurement of stuff moving around. When you feel hot, it means a lot of stuff is moving near you (the air, for example).
In space, there’s almost no stuff. Because of that, there’s basically no heat.
Latest Answers