A year is the time it takes the Earth to complete one revolution of the Sun (between 365.24 and 365.26 days depending on the point of reference).
Gaia has been active since the following:[]
- 2003 - First year
- 2004 - Second year / First anniversary
- 2005 - Third year / Second anniversary
- 2006 - Fourth year / Third anniversary
- 2007 - Fifth year / Fourth anniversary
- 2008 - Sixth year / Fifth anniversary
- 2009 - Seventh year / Sixth anniversary
- 2010 - Eighth year / Seventh anniversary
- 2011 - Ninth year / Eighth anniversary
- 2012 - Tenth year / Ninth anniversary
- 2013 - Eleventh year / Tenth anniversary
- 2014 - Twelfth year / Eleventh anniversary
- 2015 - Thirteenth year / Twelfth anniversary
- 2016 - Fourteenth year / Thirteenth anniversary
- 2017 - Fifteenth year / Fourteenth anniversary