Historical clue formulations

• Cool, giant sun — 2018-01-09
• Relatively cool red giant — 2017-05-09
• Celestial cool red giant — 2016-09-05
• Cool red giant — 2016-01-12
• Cool red giant — 2014-08-29
• *Astronomical red giant — 2014-08-20
• Relatively cool red giant — 2014-06-03
• Cool red giant — 2012-08-03
• Chi Cygni, for one — 2011-11-20
• Astronomical red giant — 2010-11-30
• Relatively cool red giant — 2008-09-18