Black absorbs all the light and reflects little to none...That light that is absorbed ultmately becomes heat...The average temperature of outer space near Earth is 50.3 degrees Fahrenheit

"Black absorbs more heat because it also absorbs more light, and light energy changes into thermal energy, which gives off heat."
https://www.reference.com/science-technology/black-absorb-heat-987c976ffb13781a

"black absorbs all the light and reflects little to none, it converts more heat. The darker shade of color, the more heat an object absorbs, while the lighter the color, the less heat it absorbs.

Why does black absorb so much heat?

A black object absorbs all wavelengths of light and converts them into heat, so the object gets warm. A white object reflects all wavelengths of light, so the light is not converted into heat and the temperature of the object does not increase noticeably."
https://profound-answers.com/why-does-black-absorb-more-heat-than-light/

"Black objects are black because almost all the light that falls on them is absorbed into the material. Little or no light is reflected back toward your eye, therefore you see black. That light that is absorbed ultmately becomes heat."
https://www.answers.com/general-science/How_does_black_absorb_light

"The average temperature of outer space near Earth is 283.32 kelvins (10.17 degrees Celsius or 50.3 degrees Fahrenheit). In empty, interstellar space, the temperature is just 3 kelvins, not much above absolute zero, which is the coldest anything can ever get."
https://sciencing.com/temperatures-outer-space-around-earth-20254.html