Inspiration from relativistic solar cosmic ray events

High energy cosmic rays provide significant information about distance celestial bodies. The solar cosmic rays produced at the closest star, the Sun, not only bring us the particle acceleration in interplanetary and at the Sun, but also help us to well understand the high energy processes of galactic cosmic rays. Solar cosmic rays also directly affect the terrestrial environment and human life. During solar cycle 23 two extreme solar cosmic ray events were recorded on 14 July 2000 and 20 January 2005. The former event occurred in the peak years of solar activity had a soft energy spectrum. However, the spectrum of the later event was the hardest in current solar cycle although it happened close the end of solar cycle. We compare their features in the aspects of flares, radio bursts, coronal mass ejections, and solar proton spectra. The reasons of differences in energy release and particle acceleration was discussed, which may be useful for us to study very high energy cosmic rays.