# How long does it take for heat to reach us from the sun?

22 February 2009

## Question

How long does it take for heat to reach us from the sun? It’s about 8 minutes, the distance between the sun and the Earth because light travels at about 1 billion km/h and the sun is about 150 million km away from the Earth.

Chris - The answer is that heat arrives in the form of light, at visible and infra-red wavelengths, largely, that's reach us from the Sun. Light is electromagnetic radiation, which propagates about about 300 million metres per second. So that too takes 8 minutes to get here...

### Sun

So if the sun is our nearest star if other stars let of heat ? Do we also collect heat from them ? If so the goldylocks zone is just a myth and we are only on this planet because the stars behind our star heat other stars around them ' just like a single block of coal will not keep its heat unless surrounded by heat

### cf: hot coal vs sun - heating

I'm not a physicist, but "a single block of coal" (or a whole fire box full of coal) does not CREATE heat via nuclear fusion. Somewhat similarly, the heat generated by the fission within a nuclear reactor does not require other reactors to be in close proximity.

### Goldilocks Zone

Heat is transferred through specific types of light (like infrared). The intensity of light varies with the inverse of the square of the distance between the light(heat) source and destination.
The distance to the Earth from the sun is defined as 1 astronomical unit (AU). The distance to the nearest star is approximately 267000 AU.
Taking these two facts into account, the approximate amount of heat we would receive from the next closest star would be .0000000014% as that from the Sun, an infinitesimal amount indeed.
This also does my take into account things like solar wind and the heliosphere which tend to work against emissions from outside the solar system.
When considering the Goldilocks zone and the plethora of other "perfect" conditions needed to support life, I find it more fascinating to think about how it got that way (or more specifically who made it so). The probability of those things occurring by chance are considered impossible by many, many orders of magnitude.

### Other stars let of heat ?

Yes, but the infra red has dissipated.
And "No" the Sun generates its own heat.

### Science question

I think it is 8 minutes as that's what is written in other websites as well