(See Holidays and observances, on sidebar at right, below)
- May 12–25 – The Space Shuttle Atlantis conducted the final servicing mission to the Hubble Space Telescope.
- May 24 – Brazilian driver Hélio Castroneves won the 93rd Indianapolis 500 in Speedway, Indiana, United States.
- May 27 – The planets Jupiter and Neptune experienced a triple conjunction.
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