Searching for Evidence of Star Spots in STEREO Heliospheric Imager (HI) Data The Heliospheric Imager on the STEREO satellites is designed to observe the interplanetary space between the Earth and the Sun in order to image Coronal Mass Ejections. However, given the number of stars which lie within the imager’s field of view and remain there for several weeks the data can also be used to look for changes in the light from these stars. Star spots, like sun spots are areas of the photosphere that are cooler than the surrounding regions and are, therefore, visibly darker. As a star spot moves across the disk of a star, there will be a corresponding drop in the light intensity; it is this drop in light that has been looked for in the HI1a data. In addition to this, first results from a model looking to predict light curves for spots of different stars will be presented. This model will determine the feasibility of detecting star spots in HI data and place constraints on sizes of spots that can hopefully be detected in this way. Observing evidence of star spots on stars similar to our Sun, will hopefully allow conclusions to be drawn about possible activity on the Sun.