I live in the Northern Hemisphere, so the Autumnal Equinox (on September 22nd this year) is thought of by many here, as the descent of Kore into the Underworld where she is enthroned as Persephone, Mistress of the Eleusinian Mysteries. As a Hellenic Polytheist who honors Persephone and her mother Demeter, I recognize this as a part of the story that describes this time of year.
However, many people forget that there is another important deity involved in this particular time of year. Helios is the one who determines when the solstices and equinoxes occur and this is also represented in the story of Demeter and Kore/Persephone.
When Haides initially brings Kore to his realm, Demeter searches for her daughter and cannot find her. It is not until Demeter speaks with Helios — who sees everything as the Titan God of the Sun — that she finds out where her daughter has been taken.
It could be said that the time approaching the Autumnal Equinox could be seen as the period when Helios saw the bringing of Kore to the Underworld. The reason I say this is that without Helios and his contribution to the finding of Queen Persephone by her mother, the change of the seasons and the sleeping of the earth in preparation for the next growing season would not be able to happen. This is because without his contribution, Demeter would not allow things to grow due to her continuing to search for Kore.
Because of this, I honor Helios in addition to the triad of Haides, Persephone/Kore, and Demeter at the equinoxes.