About a year ago, as an exercise in learning the iCal data format, I hand built an ICS file that contains the days and times of all the Solar Ephemeris events, that is, the Solstices, Equinoxes, Perihelions, and Aphelions, from 1990 to 2020.
If you are running Outlook or Mac iCal, you can import it by clicking on or importing from this link.
If you are using Google Calendar put "Solar Ephemeris" in the gcal search box and hit the "Search Public Calendars" and add it to your calendar set.
