Sun TFP

The Sun (also referred to as Sol) is the closest star to Earth, a miasma of incandescent plasma, a gigantic nuclear furnace where hydrogen is built into helium at a temperature of millions of degrees.

Transformers Prime
The sun has appeared during several episodes.

Transformers: Robots in Disguise
The sun appeared in full circle effect when Hammerstrike was diving into the ocean in Trust Exercises.