LA JOLLA, Calif. — A riveting view of the sunset known as “Salkhenge” took place Thursday evening at the Salk Institute in La Jolla.

The rare sighting, which only occurs during the spring and fall equinoxes, featured the sun aligning with the scientific research institute’s “River of Life” — a slender murmuring stream along the travertine to point to the sea, according to organizers.

Institute founder Jonas Salk calls the “River of Life” a “trickle of knowledge produced by this facility, spilling out into the body of knowledge, symbolized by the ocean. Thus, we feel a connection to a higher purpose.”

The sun aligned with the “River of Life” at 6:46 p.m.