Mercury Polar Ice
Arecibo observations confirm a strong polar radar signature on Mercury that supports the interpretation of ice in permanently shadowed craters.
Historical biography archive · Updated 2026-11-03
John Harmon Biography and Timeline
Follow John Harmon through 2 dated historical records for United States of America.
John Harmon, historical timeline
A chronological timeline drawn from matching World History Database records.
2Distinct records
1 of 1Page
1991–1992Years on this page
1991
1992
Mercury South Polar Ice
Harmon observes Mercury again when the southern hemisphere is favourably presented, helping confirm a south-polar radar-bright feature.
Records, sources and methodology
These dates and descriptions come from the historical_events database. Exact duplicate records have been collapsed. Names are grouped by the country, Name 2 and Name 1 fields; records with missing Name 2 cannot be reliably assigned to an individual biography. Check the underlying sources before formal citation.