# Sunlight **URL:** \ **Category:** Factual Questions\ **Created:** [August 30, 2000, 9:51pm UTC](https://boards.straightdope.com/t/sunlight/31411 "2000-08-30T21:51:46Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![yamo1](https://avatars.discourse-cdn.com/v4/letter/y/e19b73/32.png) [@yamo1](https://boards.straightdope.com/u/yamo1)\ **Post date:** [August 30, 2000, 9:51pm UTC](https://boards.straightdope.com/t/sunlight/31411/1 "2000-08-30T21:51:46Z")
Are the heat and light of the sun one thing or two things? ---
**Author:** ![Ozone](https://avatars.discourse-cdn.com/v4/letter/o/e95f7d/32.png) [@Ozone](https://boards.straightdope.com/u/Ozone)\ **Post date:** [August 30, 2000, 10:53pm UTC](https://boards.straightdope.com/t/sunlight/31411/2 "2000-08-30T22:53:12Z")
I’m not totally sure on this, but I’m fairly confident that they are the same. Photons zip through space, bringing with them, heat and light. ---
**Author:** ![Arjuna34](https://avatars.discourse-cdn.com/v4/letter/a/eb8c5e/32.png) [@Arjuna34](https://boards.straightdope.com/u/Arjuna34)\ **Post date:** [August 30, 2000, 10:56pm UTC](https://boards.straightdope.com/t/sunlight/31411/3 "2000-08-30T22:56:54Z")
It depends on what you mean by “thing.” Heat from the sun is radiated via photons, and so is visible light. Photons of visible light have a different wavelength than photons generally considered as carrying “heat” (i.e. the infrared part of the spectrum). Are photons of different wavelengths the same “thing?” It depends on the context. Arjuna34 ---
**Author:** ![Caldazar](https://avatars.discourse-cdn.com/v4/letter/c/8e8cbc/32.png) [@Caldazar](https://boards.straightdope.com/u/Caldazar)\ **Post date:** [August 30, 2000, 11:01pm UTC](https://boards.straightdope.com/t/sunlight/31411/4 "2000-08-30T23:01:11Z")
What we perceive as “heat energy” is really just atoms vibrating rapidly; The faster they vibrate, the higher the temperature. Heat is transferred when a faster vibrating atoms contacts a slower vibrating atom; the faster vibrating atom slows down; the slower one vibrates more. Since space is essentially a vacuum, heat energy cannot be transferred through space. Sunlight heats objects because one portion of sunlight (mostly in the infra-red range) can be absorbed by objects. The energy of absorbed infra-red light causes the atoms to vibrate faster, making the object warmer. ---
**Author:** ![Phobos](https://avatars.discourse-cdn.com/v4/letter/p/3d9bf3/32.png) [@Phobos](https://boards.straightdope.com/u/Phobos)\ **Post date:** [August 31, 2000, 1:15pm UTC](https://boards.straightdope.com/t/sunlight/31411/5 "2000-08-31T13:15:47Z")
> [@](#): > > \*Originally posted by Caldazar \* > \*\*Since space is essentially a vacuum, heat energy cannot be transferred through space. > \*\* There’s no convection or conduction of heat to speak of, but there’s still the radiation of heat, as you mentioned. (heat radiation is still a valid type of heat transfer) ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [August 31, 2000, 3:53pm UTC](https://boards.straightdope.com/t/sunlight/31411/6 "2000-08-31T15:53:52Z")
Heat and light are different types of energies. Heat is transferred by conduction, convection, or radiation. In convection heat is transferred by a hotter region flowing into a cooler region. In conduction, heat is transferred by direct contact. In radiation, heat is transferred by radiation, which can transverse a vacuum. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 31, 2000, 5:13pm UTC](https://boards.straightdope.com/t/sunlight/31411/7 "2000-08-31T17:13:54Z")
You’re all missing the point. Radiant heat is identically equal to light. All light will transmit energy which can (and usually will) be converted to molecular vibrations (heat), not just infrared-- The only reason that we think of infrared as heat is that that’s the peak emission of most things we’re familiar with, such as animal bodies. The mechanism by which a 300 K animal body produces infrared is the exact same mechanism by which the 5,770 K solar surface produces visible light, and the mechanism by which infrared is absorbed and turned into heat is the same as that by which visible light is absorbed. ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [August 31, 2000, 5:44pm UTC](https://boards.straightdope.com/t/sunlight/31411/8 "2000-08-31T17:44:44Z")
I knew Chronos would set us straight, if he deigned to do so. However, how can something be “idenitcally equal”? Either it is identical (the same) or it is equal. It cannot be identically equal. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 31, 2000, 7:21pm UTC](https://boards.straightdope.com/t/sunlight/31411/9 "2000-08-31T19:21:49Z")
“Identically equal” means that two things are the same by necessity; it’s two words for the same phenomenon. For instance: The number of bananas in my fridge is equal to the number of garlic cloves in my fridge. They’re not identically equal, because it’s easily possible for me to have different numbers of them. I just happen to have two of each. Light and radiant heat, however, are the same thing, not just two different things which happen to be similar. Hence, they’re identically equal. ---
**Author:** ![Phobos](https://avatars.discourse-cdn.com/v4/letter/p/3d9bf3/32.png) [@Phobos](https://boards.straightdope.com/u/Phobos)\ **Post date:** [September 1, 2000, 12:59pm UTC](https://boards.straightdope.com/t/sunlight/31411/10 "2000-09-01T12:59:29Z")
> [@](#): > > \*Originally posted by Chronos \* > \*\*The only reason that we think of infrared as heat is that that’s the peak emission of most things we’re familiar with, such as animal bodies. The mechanism by which a 300 K animal body produces infrared is the exact same mechanism by which the 5,770 K solar surface produces visible light, \*\* I’ve always wondered about that - - thanks.