| Astronomy Day | |
| Status: | Active |
| Genre: | Astronomy-related events and competitions |
| Date: | Saturday between mid-April and mid-May on or just before the first quarter moon |
| Frequency: | Semi-annually (Spring and Fall) |
| Country: | United States and later others |
| Years Active: | since 1973 |
| Participants: | Astronomers and astronomy enthusiasts |
| Website: | astronomyday.astroleague.org |
Astronomy Day is an annual event in various countries, intended to provide a means of interaction between the general public and various astronomy enthusiasts, groups and professionals.
This event was started in 1973 by Doug Berger, the president of the Astronomical Association of Northern California. His intent was to set up various telescopes in busy urban locations so that passersby could enjoy views of the heavens. Since then the event has expanded and is now sponsored by a number of organizations associated with astronomy.[1]
Originally, Astronomy Day occurred on a Saturday between mid-April and mid-May, and was scheduled so as to occur at or close to the first quarter Moon. In 2007, an autumn Astronomy Day was added. It was scheduled to occur on a Saturday between mid-September and mid-October so as to be on or close to the first quarter Moon.
The lunar influence on the schedule means that the events happen on a different date each year, rather than set calendar dates. The table below shows the dates for up coming Astronomy Days:
| Season | Astronomy Day | First Quarter Moon | |
| 2024 | Spring | May 18 | May 15 |
| Autumn | October 12 | October 10 | |
| 2025 | Spring | May 3 | May 4 |
| Autumn | September 27 | September 29 |
| Season | Astronomy Day | First Quarter Moon | |
| 2005 | Spring | April 16 | April 16 |
| 2006 | Spring | May 6 | May 5 |
| 2007 | Spring | April 21 | April 24 |
| 2008 | Spring | May 10 | May 12 |
| 2009 | Spring | May 2 | May 1 |
| 2010 | Spring | April 24 | April 21 |
| Autumn | October 16 | October 14 | |
| 2011 | Spring | May 7 | May 10 |
| Autumn | October 1 | October 3 | |
| 2012 | Spring | April 28 | April 30 |
| Autumn | October 20 | October 21 | |
| 2013 | Spring | April 20 | April 18 |
| Autumn | October 13 | October 11 | |
| 2014 | Spring | May 10 | May 7 |
| Autumn | October 4 | October 1 | |
| 2015 | Spring | April 25 | April 25 |
| Autumn | September 19 | September 21 | |
| 2016 | Spring | May 14 | May 13 |
| Autumn | October 8 | October 9 | |
| 2017 | Spring | April 29 | May 2 |
| Autumn | September 30 | September 27 | |
| 2018 | Spring | April 21 | April 22 |
| Autumn | October 13 | October 16 | |
| 2019 | Spring | May 11 | May 11 |
| Autumn | October 5 | October 5 | |
| 2020 | Spring | May 2 | April 30 |
| Autumn | September 26 | September 23 | |
| 2021 | Spring | May 15 | May 19 |
| Autumn | October 9 | October 12 | |
| 2022 | Spring | May 7 | May 8 |
| Autumn | October 1 | October 2 | |
| 2023 | Spring | April 29 | April 27 |
| Autumn | September 23 | September 22 |
The Astronomical League canceled the in-person event in 2020 due to the global pandemic of COVID-19 virus.[2] Some organizations, such as the Lowell Observatory, hosted virtual events to continue the tradition.[3]