The Moon Presents Unique Opportunities For High-Impact Astronomy That Could Enhance Our Understanding Of Our Solar System, The Possibility Of Life Beyond Earth, And The Evolution Of The Universe. A Handful Of Locations On The Lunar Surface Are 'sites Of Extraordinary Scientific Importance' (SESIs) For Such Studies, Presenting Opportunities For Astronomical Research Unmatched Anywhere Else. For Instance, The Farside Of The Moon, The Most Radio-Quiet Location In The Inner Solar System, Could Allow For The Emplacement Of Telescopes To Study The Cosmic Dark Ages In Ways That Are Impossible Elsewhere. However, We Are Also On The Cusp Of A Broader Lunar Renaissance. A Flurry Of Upcoming Missions, Both Scientific And Non-Scientific, Will Target Some Of These Very Same Sites And Threatens To Degrade Their Value To Science. Protecting These Sites Is An Urgent Matter. Two Major International Efforts To Create Rules For Activities On The Moon Are Afoot, But So Far Neither Emphasizes Protecting SESIs. To Safeguard The Exceptional Scientific Opportunities On The Moon, Astronomers Should Engage These International Rulemaking Efforts And Steer Them Towards Ensuring The Preservation Of SESIs For Research And Discovery. We Propose Elements Of A Programme Of Action To Adopt During A Crucial, But Closing, Window. This Article Is Part Of A Discussion Meeting Issue 'Astronomy From The Moon: The Next Decades (Part 2)'.