The year 1999 in science and technology involved some significant events.
Astronomy and space exploration
Total solar eclipse of August 11, viewed from France
- January 31 – A total penumbral lunar eclipse
- February 7 – Stardust is launched on a mission to collect samples of a comet coma, and return them to Earth.
- February 16 – Annular solar eclipse, visible from Australia.
- July 20 – Mercury program: Liberty Bell 7 is raised from the Atlantic Ocean.
- July 28 – Partial lunar eclipse, visible from Australia, eastern Asia, and western North America.
- July 31 – NASA intentionally crashes the Lunar Prospector spacecraft into the Moon, thus ending its mission to detect frozen water on the moon's surface.
- August 11 – Total solar eclipse, visible from Europe, across the Middle East, and ending in India.
- December 16 – The Beethoven Burst (GRB 991216) is one of the most powerful detected Gamma-ray bursts.
- NASA loses two Mars probes, the Mars Climate Orbiter and the Mars Polar Lander.
- The Subaru 8.3 m and Gemini North 8.1 m reflecting telescopes open at the Mauna Kea Observatory in Hawaii.
- The Cetus Dwarf galaxy is discovered.
- Elements 118 and 116 are claimed to be made for the first time. Later retracted when results could not be replicated.
Physiology and medicine
- The first BlackBerry is released, using the same hardware as the Inter@ctive pager 950, and running on the Mobitex network.
- February 21 – Gertrude B. Elion (b. 1918), American pharmacologist, Nobel laureate in Physiology or Medicine.
- February 25 – Glenn T. Seaborg (b. 1912), American physical chemist, Nobel laureate in Chemistry.
- April 28 – Arthur Leonard Schawlow (b. 1921), American physicist, Nobel laureate in Physicist.
- May 8 – Edward Abraham (b. 1913), English biochemist.
- May 26 – Waldo Semon (b. 1898), American inventor.
- July 8 – Pete Conrad (b. 1930), American astronaut.
- November 11 – Vivian Fuchs (b. 1908), English geologist and explorer.