On 30 May, 1965, Manuae attracted what at the time was the largest gathering ever of solar astronomers to observe a total eclipse from a single site. New Zealand, Australia, the UK, USA, Germany, Japan and Russia all sent teams of scientists. It was considered to be the best place on earth to witness the phenomenon. The skies were clear at first, but but just before totality (when the sun is totally obscured by the moon's shadow), a large cloud appeared.
On 31 May, the Cook Islands Administration issued stamps to commemorate the eclipse. And a post office was set up on Manuae so the scientists could, in those pre-internet days, tell the world about what they'd seen and speed their correspondence on its way with an appropriate reminder!
(The price on each stamp is in the UK's pre-decimal shillings and pence)