Several unreliable sources list January 19 as Quark Day.
Quarks are sub-atomic particles that make up protons, neutrons, and electrons. No one has seen a quark at any time. Their existence was proposed by physicists Murry Gell-Mann and George Zweig in 1964 to explain some electron scattering phenomenon in the Stanford Linear Accelerator Center. For this discovery they jointly won the 1969 Nobel Prize in Physics.
Standard model of elementary particles: the 12 fundamental fermions and 5 fundamental bosons. Brown loops indicate which bosons (red) couple to which fermions (purple and green). Please note that the masses of certain particles are subject to periodic reevaluation by the scientific community. The values currently reflected in this graphic are as of 2019 and may have been adjusted since. For the latest consensus, please visit the Particle Data Group website linked below.
https://www.fnal.gov/pub/inquiring/matter/madeof/index.html
365 Holidays a Year 