Temperature in a vacuum?

Here is a recent curiosity I had about what happens if you place a thermal measurement device in a high vacuum environment.

To be real, if a proper temp probe ratted for high vacuum was used, it would read the last temperature the sensor was at before the air was removed. Being that with non conduction or convection from the air around the sensor, the only way the sensor could lose energy would be through radiation, and that is a very slow process. The light in the lab bombarding the sensor would most likely match or overpower this loss, and the temperature would most likely go up slowly. I may try and hunt down a proper sensor and prove my hypothesis.