Both a <a href="https://en.wikipedia.org/wiki/Blue_moon" id="mwAYs" rel="mw:WikiLink" title="Blue moon">blue moon</a> and a <a href="https://en.wikipedia.org/wiki/December_2009_lunar_eclipse" id="mwAYw" rel="mw:WikiLink" title="December 2009 lunar eclipse">lunar eclipse</a> occur.