The year 2005 in science and technology included many events, some of which are listed below.

Astronomy

• February 23 - Astronomers announce the discovery of a galaxy, VIRGOHI21, that consists almost entirely of dark matter. The results are to appear in Astrophysics Journal.
• March 23 - Two independent teams report the observation of light from planets circling two different stars, using the Spitzer infrared space telescope. Both groups detect a slight dimming in the light intensity during conjunction, when the planet is moving behind its sun's disk (occultation). (SpaceflightNow) Results will be published in Nature and Astrophysics Journal.

Climatology

• January 27 - Scientists behind the climateprediction.net project, a distributed computing project run from Oxford University, announce that first results indicate a long term surface temperature increase due to global warming of between 2 and 11 degrees Celsius as a consequence of doubling carbon dioxide levels, with most of the simulations predicting a temperature rise of around 3.4 °C. The results are published in Nature.

Paleontology

• January 13 - Chinese paleontologists announce the discovery of fossils of Repenomamus robustus and Repenomamus giganticus, mammals that lived 130 million years ago. The fossil discoveries indicate that these mammals preyed on small dinosaurs. The results are published in Nature.
• February 17 - Two Ethiopian fossil skulls originally found in 1967 by Richard Leakey, Omo I and Omo II, are re-dated at 195,000 years old, making them the oldest Homo Sapiens remains known. The results are published in Nature.

Space exploration

• January 14 - The Huygens probe was successfully sent into the atmosphere of Titan and returns science data to Earth via the Cassini orbiter. It survives the landing on the surface of Titan and sends pictures and other data for more than an hour afterwards.
• January 26 - ESA's SMART-1 begins sending back close range pictures of the lunar surface
• February 7 - NASA announce budget plans - in the announcement, they state that a mission to service the Hubble space telescope will not take place, and that a robotic mission to deorbit the telescope with a safe descent into an ocean will take place. The Jupiter Icy Moons Orbiter (Jimo) mission is also cancelled.
• February 12 - ESA successfully launch an Ariane 5 ECA carrying three satellites. The previous attempt to launch the new design of rocket, in December 2002, failed when the rocket deviated from its course minutes into the flight.

Appointments

• January 26 - The NIH announce that Elizabeth Nabel will succeed Claude Lenfant as director of the US National Heart, Lung, and Blood Institute.

• February 7 - The National Academy of Sciences elects Ralph Cicerone as its next president, to begin his 6-year term on 1 July. He takes over from Bruce Alberts .
• February 25
  • - Robert Kirby-Harris is appointed as Chief Executive of the UK's Institute of Physics.
  • - Keith Mason is appointed as the new head of the Particle Physics and Astronomy Research Council in the UK.
  • - Daniel Höchli is appointed director of the Swiss National Science Foundation.
• April 13 - Michael D. Griffin is confirmed by the U.S. Senate as the next NASA administrator, succeeding Sean O'Keefe.

Other events

• February 8 - Yale University win more than $1 million in damages and attorney's fees, along with the patent rights relating to electrospray ionization from former professor and Nobel Prize winner John Fenn.

Deaths

• February 3 – Ernst Mayr (b. 1904), leading evolutionary biologist.
• February 6 - Hubert Curien (b. 1924), former President of CERN and first chairman of ESA.
• February 10 - D. Allan Bromley , director of Yale's A. W. Wright Nuclear Structure Laboratory
• March 6 - Hans Bethe (b. 1906), Nobelaureate in Physics (1967) for his discoveries concerning the energy production mechanism in stars.