Awareness and education day for the movement of the Solar System
Diagram of the Milky Way. The current position of the Solar System shown by an arrow.
Galactic Tick Day
Observed by
international
Type
Educational
2023 date
10 September
2025 date
5 June
Galactic Tick Day is an awareness and education day that celebrates the movement of the Solar System around the Milky Way galaxy.[1][2][3][4]
The day occurs at a regular interval of 1.7361 years (or 633.7 days),[5] which is called a galactic tick. The interval is derived from one centi-arcsecond of a galactic year, which is the Solar System's roughly 225-million-year trip around the Galactic Center.[6] One galactic tick is only about 0.00000077 percent (1/[360 × 60 × 60 × 100]) of a full galactic year.[7]
The Galactic Tick Day was retroactively calculated to begin on the day Hans Lippershey filed the patent for the telescope on 2 October 1608.[8] The first observance of the holiday was on 29 September 2016, the 235th Galactic Tick Day.[9] Below is a list of further observances:
Galactic Tick Day from Galactic Tick on YouTube
