Galactic Tick Day
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]
Occurrences
    
The first Galactic Tick Day took place one galactic tick after 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:
| GTD number | Date | Ref | 
|---|---|---|
| 235th | 29 September 2016 | [9] | 
| 236th | 26 June 2018 | [4] | 
| 237th | 21 March 2020 | [10] | 
| 238th | 15 December 2021 | [11] | 
References
    
- "You Should Celebrate Galactic Tick Day, the New Holiday That Spans the Milky Way". Popular Mechanics. 23 August 2016.
 - MacDonald, Fiona. "Happy Galactic Tick Day! You just moved around the Milky Way". sciencealert.com.
 - Schramm, Michael (29 September 2016). "What's a galactic tick (and why are we celebrating it today?)". Michigan Radio.
 - Sedacca, Matthew (29 September 2016). "Today Is "Galactic Tick Day"!". Nautilus (science magazine).
 - "Se acerca el Galactic Tick Day ¿Qué se celebra?". Europa Press (news agency) Ciencia Plus.
 - "'Galactic Tick Day' Celebrates Sun's Trip Around the Galaxy". Space.com. 6 September 2016.
 - "Strange Science: Earth reaches Galactic Tick Day!". KIAH News Fix.
 - Gray, Frank. "California man hopes to inspire galactic awe". The Journal Gazette.
 - Goldstone, Heather. "Galactic Tick Won't Give You Lyme, But Might Make Your Head Spin". WCAI. Retrieved 27 September 2016.
 - "March 2020 Southworth Planetarium Show Schedule". University of Southern Maine.
 - @GalacticTick (22 March 2020). "The next Galactic Tick Day is December 15, 2021!" (Tweet) – via Twitter.
 
External links
    
| External video | |
|---|---|
- Galactic Tick website
 - IFLScience.com article about Galactic Tick Day
 - Disquiet Junto Project 0248: Galactic Tick musical compositions on SoundCloud
 - GalacticTick on GitHub