On: Tested: Black 4.0, the "blackest black" is a lot b...

[vincnetas]

I think there is a reason why the satellites are reflective. One thing that comes to mind is to not overheat.

[Faaak → vincnetas]

Hard to dissipate heat when conduction and convection are basically null.

[creshal → Faaak]

It's why Starlink satellites already switched away again from black painted satellites (that light up like christmas trees on IR anyway), to having sunshades that reflect the light away at angles pointing away from Earth, to keep the light away from both astronomic observation and the sats.

[bbarnett → Faaak]

Heat radiates as IR and other such, even without air.

Fun fact, black both absorbs and radiates heat faster.

[trashtester → bbarnett]

Only if it's also "black" in the IR spectrum.

In fact, an object that is completely reflective in the IR spectrum, but black in the visible spectrum would get really hot really easily.

[itishappy → trashtester]

The reverse is also true! An object that is black in the IR, but reflects the visible becomes cooler than ambient temperatures!

[HenryBemis → bbarnett]

Of course, have you touched a black surface? If it wouldn't radiate it wouldn't be hot ;)

[schoen → HenryBemis]

Your sense of heat when touching things is mainly due to conduction, not radiation, isn't it?

[HenryBemis → schoen]

Hmm the radiator that is keeping my legs warm would disagree with you, but I'm not a physicist so I will simple shut myself up :)

[PhilipRoman → HenryBemis]

Well it's a pretty big difference in terms of intensity, sitting next to a radiator for a few hours is comfortable, but touching one would give me a burn in a matter of seconds (screw you whoever decided that my apartment must be warmed to 25 degrees)