Position of the inner planets and the Solar TErrestrial RElations Observatory (STEREO, Kaiser et al. 2008) on July 10, 2016. The light blue shaded area shows the angular separation that is referred to as the aligned phase, and spans ±45° ahead and behind Earth’s heliographic longitude; SIRs and CIRs observed during this period of time are called aligned events. Minimal temporal separation between the measurements of the same structure is given when both planets lie on the same arm of the Parker spiral that is depicted as bent solid gray lines under the approximate SW speed of 400 km s⁻¹. Credits: Stereo Science Center.