You won't immediately freeze if you enter space without a suit. You'll die almost immediately, but it will be because your blood will begin to boil because of the lack of pressure kinda like an extreme form of divers sickness - it's just not the cold that'll get you first.
FYI; that's not how it works, you and the rock you mentioned in an earlier comment cannot have the same temperature of -18C. This is due to differences in material, and geometry to a lesser extent.
Even if you were rock-shaped, the rates of energy absorption and radiation is what determines your remains' temperature, this ratio differs for different materials, and thus difference fiilnal temperatures.
The total available energy from the sun in LEO averages about 1.36KW/m^2, and more than this is radiated away by current deployed technology.
No, not just a bit. It varies by hundreds of degrees depending on the materials α/ε ratio.
Your mental model is off: materials that good absorbers but poor emitters will get very hot, and the flip-side stay cool, and are used to make the cooling elements in the ISS . The temperature of ball of black nickel at 1 AU will settle at balmy 239C - not -18C. Polished Aluminum -> roughly 145C.
My nickel guy is gonna be so disappointed.
I do understand the correction, so thank you. Doesn’t change my point at all, and I fear we are talking past each other so I’ll call it a day.