An Astronomical Timeline

Compiled by Brian Timmins

Page Three of Five

Page 1	Pre-Recorded History to 1682
Page 2	1683 - Newton's "Principia" to 16thJuly, 1968
Page 3	20th July, 1969 - Armstrong & Aldrin on the Moon to the end of the 20th century
Page 4	1st January 2001 to the 31st December 2007
Page 5	1st January 2008... Onwards and Upwards...

Modern Astronomy - The Twentieth Century (...continued)

1969

The proper coming of the space age, man lands on the moon

• 20 July: President John F. Kennedy initiated the Apollo program amidst a tense Cold War political environment. In a speech to Congress on 25 May 1961, Kennedy outlined his Apollo program, a plan to send an American to the Moon by the end of the decade. This program, he hoped, would remind the world of America’s enormous technical capability. The Apollo program succeeded. On 20 July 1969, the world witnessed what was arguably the most astonishing technological achievement in history, Apollo 11 being perhaps the most famous venture of all time. The craft had begun its historic voyage on 16 July 1969, taking off on board a Saturn 5 booster rocket, the crew being - Commander: Neil Armstrong, Command module pilot: Michael Collins, Lunar module pilot: Edwin 'Buzz' Aldrin. This was the first time that human beings had attempted to land on another heavenly body. The whole world watched with bated breaths...

  'The Eagle has landed'

  Four days after take off, Armstrong made a perfect landing, in the Mare Tranquillitatis region of the Moon. Apollo 11 had been fitted with long spikes on the ends of its legs, as mission planners were uncertain how deep the lunar dust was going to be. In fact, the spikes penetrated only a short way into the soil. Armstrong and Aldrin had to jump nearly a metre down from the bottom rung of the ladder to the Moon's surface. As Neil Armstrong became the first man to set foot on the Moon, he uttered the immortal words "That's one small step for man, one giant leap for mankind." He and "Buzz" Aldrin spent two hours on the lunar surface, collecting rock and soil samples and taking photographs. They also left behind scientific apparatus, including a seismograph to measure moonquakes, and a laser reflectometer which allowed incredibly accurate measurements of the distance between the Earth and the Moon.
  
  If you have a broad sense of humour, go read the story
  "Mr Gorsky", concerning the landing, on my Humour Page.

Las Campanas Observatory founded.

Observations start at Big Bear Solar Observatory, located in Big Bear, California

1970

• 11 February: First launch of a Japanese spacecraft, by Lambda 4S rocket.
• 17 April: Apollo 13 forced to abort Lunar Mission when oxygen tank explodes. Crew managed safe return to Earth.
• 24 April:
  Launch of first Chinese artificial satellite.
  A CZ-1 rocket launched the first Chinese artificial satellite DFH-1 marking China's entry into the space age.
  
  
• 17 November:
  Lunokhod 1 arrives safely on the moon's suface
  The Soviet Luna 17 spacecraft landed the first roving remote-controlled robot on the Moon. Known as Lunokhod 1, it weighed just under 2,000 pounds and was designed to operate for 90 days while guided in real-time by a five person team at the Deep Space Center near Moscow, USSR, Planet Earth. The futuristic looking eight wheeler rode on top of a descent module which extended ramps from both sides offering alternative routes to the surface in case one side was blocked by boulders. Lunokhod 1 was to actually tour the lunar Mare Imbrium (Sea of Rains) for 11 months in one of the greatest successes of the Soviet lunar exploration program. This Lunokhod's operations officially ceased on October 4, 1971, 14 years after the launch of Sputnik.
  [Cite: NASA :: More… ]
  
  
• 12 December: Launch of the first serious high-energy astronomy mission, "Small Astronomy Satellite 1 (SAS-1)", a pioneering orbiting X ray observatory.

Astronomers discover that Saturn's rings are composed of ice.

Copernicus space telescope launched.

The Soviet spacecraft Venera 7 lands on Venus, the first man-made craft to land on another planet and return information to the Earth. After landing an antenna was extended, and signals were returned for 35 minutes. Another 23 minutes of very weak signals were received probably because the capsule bounced onto its side on landing and the medium gain antenna was not pointed correctly for strong signal transmission to Earth.



Vera Rubin uses the Doppler effect to deduce the rotation speed distribution of the great M31 galaxy in Andromeda, an early suggestion of unaccounted "dark mass" in the universe.


The French astronomer Antoine Labeyrie described a method whereby atmospherically induced blurring can be thwarted to obtain resolved detail down to the theoretical diffraction limit. Labeyrie's technique of "speckle interferometry" uses high-magnification, short-exposure snapshots to freeze out the instantaneous effects of turbulence and then applies mathematical techniques to remove these effects. The method works best when the object being observed is simple in appearance and not too extended in size. Its limitations superbly match the needs for studying binary star systems, pairs of stars bound by their mutual gravitational attraction into elliptical orbits about a common center of mass.

Cerro Tololo 158-inch optical reflecting telescope begins operation, located in Cerro Tololo, Chile. The Observatory is located about 500km north of Santiago, Chile, about 52km ESE (80km by road) of La Serena, at an altitude of 2200 meters. It lies on a 34,491Ha (85,227 ac.) site known as "Estancia El Tortoral" which was purchased by AURA on the open market in 1967 for use as an astronomical observatory.
[ More… ]

Kitt Peak National Observatory 158-inch optical reflecting telescope begins operation, located near Tucson, Arizona. It was selected in 1958 as the site for a national observatory under contract with the National Science Foundation (NSF) and was administered by the Association of Universities for Research in Astronomy. The land was leased from the Tohono O'odham under a perpetual agreement. In 1982 NOAO was formed to consolidate the management of three optical observatories, the National Solar Observatory facilities at Kitt Peak and Sacramento Peak, New Mexico, and the Cerro Tololo Inter-American Observatory in Chile. Kitt Peak is located 56 miles southwest of Tucson, Arizona, and has a Visitor Center open daily to the public.
[ More… ]

Uhuru x-ray telescope satellite. The first satellite devoted exclusively to the study of non-solar x-rays in space was launched by an international team from a platform off the coast of Kenya on December 12, 1970. It was named Uhuru, meaning freedom in Swahili to mark the fact that the date represented the 7th anniversary of Kenyan independence. Uhuru scanned the x-ray sky using two collimated x-ray telescopes pointing in opposite directions. In its three years of operation it mapped more than 200 X-ray sources and provided early evidence for the existence of black holes as well as a binary x-ray source.By May 1971 the satellite had completed full systematic scanning of the galactic plane and had covered some 95% of the celestial sphere
[ More… ]

1971

• 19 April:The Russians launch Salyut I, the first orbital space station. Salyut 1 was the world's first space station. It was derived from the Almaz reconnaissance platform designed in the 1960s by Soviet aerospace engineer Vladimir Chelomey and adapted for use with the Soyuz manned spacecraft originally developed by his rival Sergey Korolyov for the Soviet Moon-landing program.
  [ More… ]
• 28 May: Soviet Mars 3 Launched.
• 2 December: Mars 3 entered orbit around Mars and due to a minor malfunction the orbit was not what was wanted, but a long period orbit. Primary objectives were to image the Martian surface and clouds, determine temperatures, topography, composition of the surface, measure the atmosphere, solar wind and magnetic fields, also to act as the communication relays between the landers and Earth. Mars descent module entered the Martian atmosphere at roughly 5.7 km/s and by aerodynamic braking, parachutes, and retrorockets, the lander achieved a soft landing and began operations. After 14.5 seconds, transmission on both data channels stopped for unknown reasons and no further signals were received at Earth from the martian surface.
• 11 December: Ariel 4. Investigated astronomical objects in the radio range.

Mariner 9 discovers dry riverbeds on Mars.

1972

• 2 March: Pioneer 10 was launched from the launch pad at Cape Kennedy, carrying Earth's first space probe to an outer planet. To accomplish this feat, Pioneer 10 had to pass through what was initially feared to be an impenetrable asteroid belt.
  [ NASA :: More… ]
  
• 21 August: Copernicus. It carried an 80-cm UV telescope and successfully carried out its observing program.
• 12 December: Small Astronomy Satellite (SAS) 42 Uhuru. The first X-ray satellite, carrying a telescope sensitive for X-ray photons of 2..20 keV energy.

Last Apollo mission to Moon. Apollo 17 concluded the series of lunar landings in which a dozen astronauts explored the Moon.

1973

• 2 March: Pioneer 10 launched towards Jupiter, arrives 4 December 1973.
• 5 April: Pioneer 11 launched towards Jupiter, arrives 5 December 1974 and carried on to Saturn, 1 September 1979.
• 14 May: Skylab was America's first space station and orbital science and engineering laboratory. Skylab was launched into Earth orbit by a Saturn V rocket as part of the Apollo program. Three crews visited the station, with their missions lasting 28, 59 and 84 days.
  [ NASA :: More… ]
  
• 10 June: Radio Astronomy Explorer (RAE) 2. Put into Lunar orbit, and investigated solar and galactic radio radiation, using the Moon to "shield" Earth with its radio noise.

Astronomers determined that the clouds of Venus were composed primarily of sulfuric acid.

UK 1.2 metre Schmidt optical reflecting telescope begins operation. It is operated by the Anglo-Australian Observatory, and located adjacent to the 3.9 metre Anglo-Australian Telescope at Siding Spring Observatory, Australia. It is a survey telescope with a 6° by 6° field of view, and has been the primary source of optical survey data in the southern sky since it was opened in 1973. The original sky survey plates have been digitally scanned by the Space Telescope Science Institute to create the Guide Star Catalog for the Hubble Space Telescope, and the Digitized Sky Survey.

1974

• 29 March: Mariner 10 (launched 3 November 1973) flies past the planet Mercury.
• 15 October: Ariel 5. Satellite devoted to X-ray astronomy.

The Anglo-Australian Telescope is a 3.9m equatorially mounted telescope operated by the Anglo-Australian Observatoryand situated at the Siding Spring Observatory Australia at an altitude of a little over 1100m. It is jointly funded?by the United Kingdom and Australia, with observing time made available to astronomers worldwide.It is equipped with a number of instruments, including the Two Degree Field facility, a robotic optical fiber positioner for obtaining spectroscopy of up to 400 objects over a 2° field of view simultaneously. The University College London Échelle Spectrograph, a high-resolution optical spectrograph which has been used to discover many extrasolar planets; and IRIS2, a wide-field infrared camera and spectrograph. The AAT was one of the last large telescopes built with an equatorial mount. More recent large telescopes have insteadadopted the more compact and mechanically stable altazimuth mount. The AAT was however one of the very first telescopes to be fully computer-controlled, and set new standards for pointing and tracking accuracy.
[ AAO :: More… ]

Mariner 10 encounters Mercury. After passing Venus, Mariner 10 encountered Mercury four times, sending back pictures of Mercury's surface. With the scorched inner planet Mercury as its ultimate target, the final Mariner pioneered the use of a "gravity assist" swing by the planet Venus to bend its flight path. Using a near-ultraviolet filter, it produced the first clear pictures of the Venusian chevron clouds and performed other atmospheric studies before moving to the small, airless, cratered globe of Mercury. Here a fortuitous gravity assist enabled the spacecraft to return at six-month intervals for close mapping passes over the planet, covering half the globe (Mercury’s slow rotation left the other half always in the dark when Mariner 10 returned).

An X-ray source is discovered in the constellation Cygnus, postulated to be a black hole.

Kitt Peak National Observatory completed.

Mariner 10 sends photos of Venus and Mercury back to Earth.

1975

• 19 April: Aryabhata. Indian Scientific Satellite, Measured X-rays from Milky Way and extragalactic regions, besides Solar and ionosphere observations.
• June 8: Venera 9 was a USSR unmanned space mission to Venus. It consisted of an orbiter and a lander. It was launched on June 8, 1975. The orbiter consisted of a cylinder with two solar panel wings and a high gain parabolic antenna attached to the curved surface. A bell-shaped unit holding propulsion systems was attached to the bottom of the cylinder, and mounted on top was a 2.4 meter sphere which held the lander. The orbiter entered Venus orbit on October 20, 1975. Its mission was to act as a communications relay for the lander and to explore cloud layers and atmospheric parameters with several instruments and experiments. It performed 17 survey missions from October 26, 1975 to December 25, 1975.
  [ Russian Spaceweb :: More… ]
  
• 11 June: Venera 11 also lands, takes pictures.
  

A 6 metre telescope is commissioned in Russia.

Astronomers discover a large amount of ethyl alcohol near the center of the Milky Way galaxy.

Cerro Tololo Inter-American Observatory completed.

Giant impact hypothesis presented as the cause of the creation of the Moon.

Soviet Soyuz 19 docks with Apollo 18.

Antoine Labeyrie builds the first two-telescope optical interferometer

Gerald Smith, Frederick Landauer, and James Janesick use a CCD to observe Uranus in the methane band. This was the first known use of CCDs in astronomy was an observation. Initially, professional astronomers were reluctant to abandon photography, yet, the new technology soon caught on. By the late 1980's, most important observatories, and even a few amateurs, were routinely using CCDs.

1976

19 June: Viking 1 soft lands on Mars. 3 September: Viking 2 soft lands on Mars.

The 6-m BTA-6 (Bolshoi Teleskop Azimutalnyi or Large Altazimuth Telescope) goes into operation on Mt. Pashtukhov in the Russian Caucasus.

For several years the two Viking expeditions returned information about Mars. The Orbiters photographed the entire surface of Mars at a resolution of 150 to 300 meters, and selected areas at 8 meters. The lowest altitude for both Orbiters was 300 km. The results showed volcanoes, lava plains, canyons, cratered areas, wind-formed features, and evidence for surface water was also determined. The Viking Landers transmitted images of the surface, took surface samples and analyzed them for composition and signs of life, studied atmospheric composition and meteorology, and deployed seismometers.

European Southern Observatory completed.

Special Astrophysical Observatory completed.

1977

• 20 August: Voyager 2 launched towards Jupiter ariving 9 July 1979, continuing to encounter Saturn 26 August 1981. Continued to Uranus, 25 January 1985 and Neptune, 25 August 1989
• 5 September: Voyager 1 launched towards Jupiter. arriving 5 March 1979, continuing to encounter Saturn 12 November 1980
  
  
• 22 October: The International Sun-Earth Explorer (ISEE) program consisted of 3 satellites. ISEE-1 and ISEE-3 were the principal US contribution to the International Magnetospheric Study, and ISEE-2 which was built and managed by ESA. ISEE-1 and 2 were launched into almost coincident orbits, and their separation in the orbit was controlled by manuvuering ISEE-2.

Rings are discovered around Uranus.

Stephen Hawking determined that black holes do radiate away some of their energy, known now as Hawking radiation.

Star Wars debuts.

1978

• 22 June:James Christy and Robert Harrington discover Pluto's moon, Charon. Pluto's mass was unknown, and was likely to remain so without a breakthrough. That came on June 22, 1978, when American astronomer James Christy was studying photographs of Pluto at the U.S. Naval Observatory. Several images of Pluto were elongated, and the pictures were thought to be defective. However, Christy found other photographs in which the bump on Pluto was in different positions. In fact, he found a series of photographs from 1970 that showed the bump progressing around Pluto in a 6-day period. Christy reasoned that Pluto must have a satellite.
  [ Image: Hubble/NASA :: More… ]
  
• 12 August: The International Sun-Earth Explorer (ISEE-3) was launched. It was inserted into a "halo" orbit about the libration point some 240 Earth radii upstream between the Earth and Sun. ISEE-3 was renamed ICE (International Cometary Explorer) when, after completing its original mission in 1982, it was gravitationally maneuvered to intercept the comet P/Giacobini-Zinner. On September 11, 1985, it flew through the tail of the comet.
• 20 September: Einstein. High Energy Astronomical Observatory 3. Carried Gamma ray telescopes.

Pioneer 12 and 13 reach Venus. After entering orbit, Pioneer 12 returned global maps of the planet's clouds, atmosphere and ionosphere, measurements of the atmosphere-solar wind interaction, and radar maps of 93 percent of the planet's surface. Pioneer 13 carried 4 probes designed to perform in-situ atmospheric measurements. Released from the carrier vehicle in mid-November 1978, the probes entered the atmosphere at 41,600 km/hr and carried a variety of experiments to measure chemical composition, pressure, density, and temperature of the mid-to-lower atmosphere.
[ NASA :: More… ]

International Ultraviolet Explorer (IUE) launched. IUE operated for over 20 years making it one of the longest serving astronomical satellites. It was a ESA/NASA-UK venture. It analysed ultraviolet light from the stars, which is blocked by the Earth's ozone layer but often carries storm signals of cosmic upheavals.
[ ESA :: More… ]


Multiple Mirror 176-inch equivalent optical/infrared reflecting telescope begins operation, located in Amado, Arizona

1979

• 21 February: Hakucho (Japan). X-ray satellite. Active until April 15, 1985.
• 5 March: Voyager 1's closest approach to Jupiter. It discovers Jupiter's rings.
  [ Image: JPL/NASA :: More… ]
  
• 2 June: Ariel 6. Satellite devoted to X-ray astronomy.
• 7 June: (India) Bhaskara-I. Primarily an Earth observing satellite, it also carried an All-Sky monitor similar to Ariel-V.
• 9 July: Voyager 2's closest approach to Jupiter.
• 24 December: First flight of Europe's Ariane rocket

Canada-France-Hawaii 140-inch optical reflecting telescope begins operation, located at Mauna Kea Observatory, Hawaii.

NASA Infrared Telescope Facility[1] 120-inch infrared reflecting telescope begins operation, located at Mauna Kea, Hawaii.

UKIRT 150-inch infrared reflecting telescope begins operation, located at Mauna Kea Observatory, Hawaii.

1980

The first multiple mirror telescope is built at Mt. Hopkins, Arizona.

In Agust Voyager 2 found subdued contrasts and color differences in Saturn's atmosphere that could be a result of more horizontal mixing or less production of localized colors than in Jupiter's atmosphere. While Voyager 1 saw few markings, Voyager 2's more sensitive cameras saw many: Long-lived ovals, tilted features in east-west shear zones, and others similar to, but generally smaller than, on Jupiter.

In November Voyager 1 found that about 7 percent of the volume of Saturn's upper atmosphere is helium (compared with 11 percent of Jupiter's atmosphere), while almost all the rest is hydrogen.

Completion of construction of the Very Large Array. This is one of the world's premier astronomical radio observatories, consisting of 27 radio antennas in a Y-shaped configuration on the Plains of San Agustin fifty miles west of Socorro, New Mexico. (It was used in the opening scenes of Arthur C Clarke's 2010: Odyssey Two - though in the film it was set at Aricebo)
[ Image: NRAO :: More… ]

1981

12 April First flight of the Space Shuttle.

Alan Guth proposes early period of inflation of universe. Guth proposed that the a number of difficulties with the standard model of the expanding universe could be explained by an enormous expansion very early in the history of the universe.

Very Large Array begins operations. The Very Large Array (VLA) is an array of 27 radio telescopes that work together to produce radio images that are comparable to those of traditional optical telescopes.

1982

European X-ray Orbiting Satellite launched.

Rings around Neptune discovered.

1983

• 25 January:
  Infrared Astronomical Satellite - IRAS
  This telescope was a joint project of the United States (NASA), the Netherlands (NIVR), and the United Kingdom (SERC). IRAS was the first observatory to perform an all-sky survey at infrared wavelengths. It mapped 96% of the sky four times, at 12, 25, 60 and 100 micrometre wavelengths. It discovered about 350,000 sources, many of which are still unidentified. A arge number (75,000) are believed to be young starburst galaxies, still active in the star-formation stage. After 10 months IRAS exhausted its helium coolant and ceased operations on November 21, 1983.
• 18 June:
  First US Woman in Space
  Sally Ride was one of 8,000 people to answer an advertisement in a newspaper seeking applicants for the space program. As a result, she joined NASA in 1978. As part of her training she was the Capsule Communicator (CapCom) for the second and third Space Shuttle flights (STS-2 and STS-3) and helped develop the Space Shuttle's robot arm. On June 18, 1983 she became the first American woman in space as a crewmember on Space Shuttle Challenger for STS-7. On STS-7, the 5-person crew deployed two communications satellites, conducted pharmaceutical experiments, and was the first to use the robot arm in space and the first to use the arm to retrieve a satellite.

Astronomers announce that the Small Magellanic Cloud may be two galaxies.

Vector bosons detected.

Sally Ride is first US woman in space.

Pioneer 10 becomes the first man-made object to travel beyond the solar system.

1986

• 28 January: Space shuttle Challenger lost with all its crew, exploding shortly after launch from Cape Canaveral.
• 20 February: Soviet space station "Mir" launched; reentered the atmosphere 23 March 2001.
• 6 March: Russia's Vega 1 flies past Comet Halley, after dropping French balloon experiment on Venus.
• 
  14 March: Europe's Giotto. European Space Agency's Giotto probe flies past Comet Halley and returns 2333 images during the Comet Halley encounter of March 13-14, 1986. All were recorded before the closest approach of 596 km; the last from a distance of 1180 km, 15 seconds before closest approach. The sequence of images highlights details on the nucleus and the dust jets emanating from the sunlit side.
  
• 26 May: Exosat (ESA). European X-ray Observatory Satellite.
• 4 November:
  
  
  Voyager 2's Encounter with Uranus.
  Activity built to a peak in late January 1986, with most of the critical observations occurring in a six- hour period in and around the time of closest approach. The spacecraft made its closest approach to Uranus at on 24 Jan. It photographed the five major moons and discovered 10 more, all relatively tiny.

Soviet Union launches first part of the Mir space station. There is a rather good interactive site concerning the progress of the Soviet MIR spacestation at "Russian Spaceweb".

Other space probes encounter Comet Halley. Altogether five space probes flew past Comet Halley at distances as small as 600 km. Images sent back by the spacecraft showed that the nucleus of Halley is very dark and larger than anticipated.

Kamiokande neutrino telescope begins operating. Shortly after it was completed, the Kamiokande telescope was one of two neutrino telescopes to detect neutrinos from a supernova in the Large Magellanic Cloud.

1987

• 23 February: The explosion of Supernova 1987A, that occurred in 168,000 B. C. was seen on Earth, becoming the first supernova visible to the naked eye since the one observed by Johannes Kepler in 1604. The unusual chemistry of SN 1987A has led many astronomers to suspect the progenitor star had merged with another star shortly before the explosion. Like many stars that have reached the end of their lives, the star that produced SN 1987A is surrounded by a gaseous nebula. Scientists have had difficulty explaining the bizarre and intricate shapes of these nebulae. Some have suggested the merger process might explain the triple rings of SN 1987A, but it has been unclear whether this was correct.
  [ Images: NASA/AAO :: More at AAO... :: More at NASA... ]
  

La Palma Observatory completed.

Soviet Union launches their first space shuttle.

In Hawaii 2 millimeter/submillimeter radio telescopes were completed on Mauna Kea: the Caltech Submillimeter Observatory (10.4m) and the James Clerk Maxwell Telescope (15m).

5-m Swedish-ESO Submillimetre Telescope (SEST) installed at the ESO La Silla Observatory.

1988

• 7 July:Phobos 1 was launched.
• 12 July:Phobos 2 was launched. These ware unmanned space missions launched by the Soviet Union to study Mars and its moons Phobos and Deimos. Phobos 2 became Mars orbiter and sent back 38 images. Both probes, unfortunately, suffered nearly complete failure. The program was funded by 14 nations - Sweden, Switzerland, Austria, France, West Germany, and the United States.
• 15 November: Soviet space shuttle "Buran" conducts its first (unmanned) flight.

Australia Telescope Compact Array aperture synthesis radio telescope begins operation, located near Narrabri, Australia.

The most distant star to date is recorded, a supernova more than 5 billion light years away.

1989

• 29 January: Phobos 2 went into Mars orbital insertion phases. It had gathered data on the Sun, Mars, and Phobos. Shortly before its final stage, during which the spacecraft was to approach within 50 m of Phobos' surface and release two landers, one a mobile 'hopper', the other a stationary platform, contact with Phobos 2 was lost - the signal failed to be successfully reacquired.
  
  
• 8 August: Hipparcos. Astrometrical satellite for measuring high precision parallaxes. Although launched successfully, the spacecraft didn't achieve its designed high orbit. Nevertheless, it was highly successful and measured 118,000 star positions at 0.001 arc seconds acuracy, plus some 1,050,000 positions at 0.025 arc seconds, in two color band ("B" and "V"), so that also over 1 million color indices were obtained.
  
  
• 25 August: Voyager 2 reaches Neptune, discovering 3 ring systems and 8 moons. Since this was the last major planet Voyager 2 could visit, it was decided to make a close flyby of the moon Triton, regardless of the consequences to the trajectory, as with Voyager 1's encounter with Saturn and its moon Titan. The probe also discovered the Great Dark Spot, which has since disappeared, according to Hubble Space Telescope observations. Originally thought to be a large cloud itself, it was later postulated to be a hole in the visible cloud deck. With the 2006 decision of the International Astronomical Union to demoted Pluto to a "dwarf planet," the 1989 fly-by of Neptune by Voyager 2 became the point when every planet in the solar system had been visited at least once by spacecraft.
  
  
• 18 November: COsmic Background Explorer (COBE). Cobe was launched in and measured the cosmological microwave background radiation. The most significant result was the discovery of very small fluctuations (order 0.0001, 10^{-5}) in the background.
  
• 1 December: Granat (USSR). Gamma ray satellite.

Japan launches a probe into lunar orbit.

New Technology European Southern Observatory completed.

United States launches Galileo probe. United States launches Magellan probe.

1990

• 5 April: Compton Gamma Ray Observatory (CGRO) (NASA). Developed as "Gamma Ray Observatory (GRO)". Carried instruments to investigate Gamma photons of energy 30 keV to 30 GeV.
• 24 April: Hubble Space Telescope (HST) (Nasa, ESA). Formerly called the "Large Space Telescope (LST)" and later simply the "Space Telescope (ST)". Originally with improperly designed optics, this spacecraft carries the largest telescope ever launched to orbit, with a 2.4-meter aperture primary mirror. When the design error was detected, a computer program was involved to get the images better, but the telescope became usable to its full capabilities only after the HST refurbishment Shuttle mission in December 1993. Since then it has delivered a bunch of premium scientific results and gorgeous images of all kinds of celestial objects. A final service mission is currently scheduled for April, 2008.
• 20 May: The Hubble Space Telescope sent back its first photographs.
  
  
• 6 June:
  
  On this day, Voyager 1, at 4 billion miles distant and speeding out of the Solar System, looked back at the earth and took this image of our planet. Carl Sagan was moved to say...
  "That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every 'superstar,' every 'supreme leader,' every saint and sinner in the history of our species lived there - on a mote of dust suspended in a sunbeam."
  
  
• 1 June: Rosat. The Roentgen Satellite (Rosat) carries a 83-cm X-ray telescope of 2.4 meter focal lenght, for observing X-ray photons of 0.1 to 2.0 keV energy. ROSAT launched (The Röntgen Satellite, was an X-ray observatory developed through a cooperative program between Germany, the United States, and the United Kingdom. The satellite was proposed by the Max-Planck-Institut für extraterrestrische Physik (MPE) and designed, built and operated in Germany. It was launched by the United States on June 1, 1990). ROSAT produced X-ray images of hot, X ray emitting objects.
• 27 June: NASA reported that a flaw in the Hubble Space Telescope was preventing it from achieving optimum focus.
• 11 July: Gamma (USSR). Gamma ray astronomy.

Graduate student Alan Hildebrand, of the University of Arizona, and his colleagues identify the 180 mile wide Chicxulub crater in Mexico, and propose it as being the most likely candidate for the catastrophic environmental changes that killed off 70% of all species around 65 million years ago. In the following years, the work of Hildebrand and his colleagues would be tested to further identify the importance of Chicxulub as the site of a K/T boundary impact. (K/T Is the abbreviation for the boundary between the Cretaceous and Tertiary time periods. K is for 'kreta', meaning chalk, and T is for Tertiary)

The NTT (New Technology Telescope) in Chile, the pride of the European astronomical community was inaugurated. Its mirrors span 3.5 meters and is the first telescope built with active or computer assisted optics.

Magellan begins radar mapping of Venus. Magellan produced an almost complete radar map of the surface of Venus.

CCDs (A charge-coupled device is an image sensor, consisting of an integrated circuit containing an array of linked, or coupled, light-sensitive capacitors. This device is also known as a Color-Capture Device.) become the detector of choice in astronomy. CCDs are much more sensitive than photographic plates and allow astronomers to detect very faint objects.

First Keck 10-m telescope completed. The Keck telescope, unlike most earlier large optical telescopes, has a mirror made of many hexagonal segments. There are now twin Keck telescopes on Mauna Keck.
[ Image: Keck Observatory :: More… ]

1991

• 5 February: Ginga (Japan). X-ray satellite successfully launched.
• 5 April: Compton Gamma Ray Observatory is launched.
• 17 July: SARA (French). Radio astronomy satellite put into orbit.
  
  
• 29 October: Galileo obtains first up-close images of asteroid (Gaspra). The Galileo spacecraft passed Gaspra at a distance of only 1,600 km. Images from Galileo showed craters and groovelike cracks. These two colour views of the asteroid Gaspra were produced by combining three images taken through violet, green, and infrared filters by the Galileo spacecraft on October 29, 1991, from a distance of about 16,000 kilometers (10,000 miles).
  [ Image: JPL/NASA :: More… ]
  (I cannot resist the temptation to observe that this asteroid, in shape, bears a striking resemblance to a certain adult toy)

Astrophysical Research Consortium completed.

CalTech may have discovered ice at Mercury's north pole.

Mauna Kea Keck Observatory completed.

Helen Sharman becomes the first British astronaut, on Soyuz TM-12.

Alex Wolszczan and Dale Frail at Pennsylvania State Univ. reported evidence of 3 extra-solar planets (exoplanets) orbiting around the spinning remains of Pulsar B1257+12. They found the pulsar in 1990 using the Arecibo radio telescope.

1992

• 7 June: EUVE. Extreme UltraViolet Explorer.
• 31 July: Eureca (ESA). European Retrievable Carrier. This reusable satellite carried Watch, the Wide-Angle Telescope for Cosmic Hard X-rays (of 6-150 keV energy).
  
  
• 12 Oct: Under the auspices of NASA, the Arecibo radio telescope in Puerto Rico began a microwave search for occupied planets. Known as SETI - Search for Extraterrestrial Intelligence. Aricebo is the world's largest single dish telescope, is simply unique. The fixed reflector on the ground is 305 meters (1000 ft) across, and almost exactly a kilometer (0.6 mile) around. The platform, suspended in mid-air (450 feet above the ground), weighs 900 tons and is about the size of a five-story building!
  
  • A short history of SETI
  • The SETI Institute
  • SETI at home
  • SETI at home for UK users
• 30 October: The Catholic Church, not before time, admits that it made a mistake when it condemned Galileo in 1633. A commission of the church, appointed by Pope John Paul II in 1980, had concluded that the Inquisition was in error in its 1632 condemnation of Galileo's support of the Copernican Theory of the solar system. Well done - only 360 years late. One might point out to The Catholic Church a variation of a purported saying of one of its more famous teachers... "Render unto your putative god that which is his - myth and legend; and unto science, that which is theirs - fact".

Astronomers discover microwave background fluctuations.

COBE satellite discovers ripples from the Big Bang.

The Very Long Baseline Array (VLBA) was completed. It is a string of 10, 25-meter radio telescopes, that stretch from the Virgin Islands to Hawaii. They operate in the cm. radio wavelengths. Data from each station is merged through radio interferometry into a primary image whose angular resolution equals that of a single telescope nearly 5,000 miles in diameter.

1993

• 20 February: ASCA (Japan). Advanced Satellite for Cosmology and Astrophysics.
• 25 April: Alexis (DoE, USA; operated by LANL). Array of Low Energy X-ray Imaging Sensors. Built and controlled from LANL.
• December: Engineers and scientists worked frantically to complete the first phase of the DUMAND project. The Deep Underwater Muon and Neutrino Detector was being set up 22 miles off the coast of Kailua-Kona, Hawaii. It was built as a kind of telescope that would provide information on the Earth's interior, on life in the deep sea, on black holes in space, as well as info on subatomic particles. It resembles a massive inverted jellyfish pinned to the seafloor. It is hoped that some high energy neutrinos will interact with matter and be transformed into a muon that will produce a blue-green light known as a Cherenkov Radiation that can be detected. It existed from about 1976 through 1995. The goal was the construction of the first deep ocean high energy neutrino detector, to be placed at 4800 m depth in the Pacific Ocean off Keahole Point on the Big Island of Hawaii. Many preliminary studies were carried out, from technology to ocean optics. A prototype vertical string of instruments suspended from a special ship was employed to demonstrate the technology, and measure the cosmic ray muon flux in the deep ocean. Data from this Short Prototype String were, for example, used to set the then best limits upon PeV energy neutrinos as might be expected from Active Galactic Nuclei. Due to a series of misfortunes it was no longer possible to communicate with the installed apparatus, so in 1995 the US DOE cancelled further efforts on DUMAND. The DUMAND goal to begin high energy neutrino astronomy is being carried forward in several ocean experiments (in order of age): NESTOR, ANTARES, and NEMO, all located in the Meditteranean Sea, as well as the venerable Lake Baikal Project in Asia, and the AMANDA/ICECUBE Project at the South Pole. The DUMAND hardware was donated to the NESTOR Project in Greece, and may yet be employed there.

ASTRO-D launched. Kitt Peak National Observatory WIYN Consortium completed.

Keck 10-meter optical/infrared reflecting telescope begins operation, located at Mauna Kea, Hawaii.

1994

• 1 November: GGS-Wind. Carried a Transient Gamma Ray Spectrometer.
• 14 Aug: Space telescope Hubble photographed Uranus with rings.

Fragments of Comet Shoemaker-Levy strike Jupiter. Tides due to Jupiter broke Comet Shoemaker-Levy into at least 18 fragments that later struck Jupiter, producing bright fireballs and new cloud features.

An asteroid passes earth at only 160,000km (100,000 miles).

Hubble Space Telescope finds evidence for a black hole at the centre of the M87 galaxy.

United States launches Clementine, a joint project of NASA and the Strategic Defense Initiative.

1995

• 18 March: IRTS/SFU (Japan). The IRTS is a cryogenically cooled infrared telescope that was launched aboard a multi-purpose space platform SFU (Space Flyer Unit). It surveyed approximately 7 % of the sky with a relatively wide beam during its 28-day mission. Four focal plane instruments made simultaneous observations of the sky at wavelengths from 1 to 1000 micron.
• 21 March:
  Mars Photographs
  The best long-range photographs ever taken of the planet Mars, from The Hubble Space Telescope
• 4 November:
  Surfsat-1 launched
  The satellite was designed, built, and tested with the help of 60 undergraduate college students from the California Institute of Technology and 14 other universities. Surfsat-1, which stands for Summer Undergraduate Research Fellowship SATellite #1, started seven years ago with a handful of summer students. Surfsat-1 contains low power radio beacons and transponders, radiating over hemispherical antennas in three microwave bands, for testing new NASA ground tracking facilities. The solar-powered spacecraft, which remains attached to the second stage of the launch vehicle, was designed to operate for at least one year.
• 17 November: ISO. Infrared Space Observatory (ESA).
• 7 December: The Galileo spacecraft reaches Jupiter, helped by "gravity assist" maneuvers involving Venus and (twice) Earth.
• 30 December:
  The Rossi X-ray Time Explorer Launched
  This satellite is to observe X-ray photons of 2-200 keV energy. The RXTE observes x-rays from black holes, neutron stars, X-ray pulsars and x-ray bursts with its 3 instruments:
  1. Proportional Counter Array
  2. High Energy X-ray Timing Experiment
  3. All Sky Monitor
  How fast and how energetic are they? Well, some pulsars spin faster than a thousand times a second. And a neutron star produces a gravitational pull so powerful that a marshmallow striking the star's surface would hit with the force of a thousand hydrogen bombs. Astronomers study changes that happen from microseconds to months in cosmic objects to learn about how gravity works near black holes, how pulsars in binary systems are affected by mass transferring from one star to the other, and how the giant engines in distant galaxies are powered.
• 30 December: Long time exposure by the Hubble telescope ("Deep Field") reveals the most distant galaxies.

Galileo probe enters Jupiter's atmosphere. An entry probe detached from the Galileo spacecraft and parachuted into Jupiter's atmosphere. The probe sent back data for about an hour before it was destroyed by high pressure and temperature.

Infrared Space Observatory (ISO) launched. ISO obtained high resolution infrared spectra and images of cool bodies and clouds of dust in the solar system, galaxy, and beyond.

The 47 Ursae Majoris system with possible planets was discovered by Marcy and Butler. Planets found orbiting stars like the Sun. Astronomers in the United States and Switzerland reported the first detections of Jupiter-like planets orbiting nearby Sun-like stars.

1996

• 30 January:
  Comet Hyakutake
  On January 30, 1996, Yuji Hyakutake in Japan discovered a new comet using 25x150 binoculars. The comet was designated Comet C/1996 B2 (Hyakutake). As subsequent observations of the new comet were obtained, Brian Marsden from the IAU Central Bureau was able to compute the comet's orbital elements, and these computations indicated that the comet will pass as close as 0.10 AU (9.3 million miles) from the Earth on March 25, 1996! The comet has become a bright naked-eye object and remained so in March, April and May in 1996. The comet had exceeded expectations, becoming the brighest comet since Comet West in 1976. A long tail of up to 100 degrees was reported, and small fragments have been observed to break off the main nucleus. Comet Hyakutake is indeed the Great Comet of 1996.
  
  
• 21 February: The Space Telescope Science Institute announced that photographs from the Hubble Space Telescope confirmed the existence of a "black hole" equal to the mass of two billion suns in a galaxy some 30 million light-years away.
• 7 March: 1st surface photos of Pluto were photographed by Hubble Space Telescope.
• 24 April: MSX. Midcourse Space Experiment. Carried IR instruments sensitive for radiation of 4.2 to 26 microns (micrometers) wavelength.
• 30 April:
  Italian X-Ray Telescope
  Launch of SAX (Italy). Later renamed BeppoSAX. X-ray satellite.
  
  
• 9 June: Alex Wolszczam describes the pulsar B1257+12, 1,300 light-years away. His measurements indicate a planetary system nearby. Other stars with planets possibly include 51 Pegasi, 70 Virginis, 47 Ursae Majoris and 55 Cancri. It was later proposed that the evidence for the planets was caused by energy waves circling their home star.
• 23 June: Two new exo-planets have been reported. One is 4 times the size of Jupiter, and revolves around the star Tau Bootes in the constellation Bootes. The other, about 60% the mass of Jupiter, revolves around Upsilon Andromedae.
• 27 June: A team of scientists using the Hubble space telescope believe that they have identified galaxies that were formed 14-7.5 Billion years ago. The images, called the Hubble Deep Field, were made in Dec. and released in Jan.
• 5 August:
  Latest picture of Jupiter's moon Io and its active volcanoes.
  [Images - Voyager Project, JPL, and NASA]
  
  
• 5 September: Astronomers using the Hubble space telescope discovered a galaxy under construction. They say 18 gigantic star clusters were packed within a space just 2 million light years across and apparently on the verge of forming a brand new galaxy. Light from the event originated 11 billion years ago.
• 30 September:
  Meyer-Womble Telescope
  The Observatory stands near the summit of Mount Evans, operated by the University of Denver. Located at 39°35?12?N, 105°38?24?W and 14,148 feet (4,312 m), it is the second highest telescope in the world. Before the Indian Astronomical Observatory became operation in 2001 it was the highest. Through a gift of $3.8 million from the estate of William Womble, construction of the facility was completed in 1996. Eric Meyer, M.D., an anesthesiologist who designed the dual-aperture 28.5-inch, f/21 Ritchey-Chretien telescope, and his wife, Barbara, donated $1 million and brought the optical lenses personally from Chicago.
  
  
• October: The Keck II telescope on the dormant Mauna Kea volcano in Hawaii began science observations.
• 30 December:
  Death of Carl Sagan
  Carl Sagan dies at the age of 62 after a two-year fight with bone marrow disease. Sagan became world-famous after his acclaimed PBS documentary, "Cosmos". He also won the Pulitzer Prize for his book, "Dragons of Eden". Sagan was deeply enthralled by the possibilty of life outside of Earth and had currently been serving as professor of astronomy at Cornell University.
  
  

Mars Pathfinder begins to transmit data.

NASA scientist announce the discovery of proof of living organisms on a Mars meteorite found in Antarctica.

The Mars Global Surveyor spacecraft indicates the probability that Mars once had large bodies of water and may still contain significant amounts of water.

Claim of evidence for fossil life in Martian meteoroid. A meteorite blasted from Mars by an asteroidal impact was found to contain possible fossil traces of ancient biological activity and life-like structures.

The Near Earth Asteroid Rendezvous spacecraft orbits the asteroid 433 Eros.

The Russian Mars 96 Orbiter fails to achieve Mars trajectory and crashed on Earth.

1997

• 12 February: Japan launches the radio telescope satellite HALKA, which is renamed VSOP. This will add a space-based component to radio telescopes on Earth, enabling finer-resolution interferometry. The combination with Earth-based radio telescopes and VSOP is termed the Very Long Baseline Space Observatory.
• 13 February: Tune-up and repair work on the Hubble Space Telescope is started by astronauts from Space Shuttle Discovery.
• 23 February: The 11-year-old Mir space station has problems when an oxygen-producing candle bursts into flame, burns for nearly 14 minutes, and sends smoke through the station, blocking the route to the Soyuz space capsule. Both oxygen generators fail in March, forcing the crew to rely on candles. Coolant leaks in April raise temperatures briefly above 86° F., causing primary air-purification systems to fail.
• 28 February: Astronomers observe, with the BeppoSAX satellite (Italy-Netherlands X-Ray satellite), that a gamma-ray burst is followed by a radiation afterglow lasting several days.
• 11 March: First ever space funerals when the ashes of Timothy Leary and Gene Roddenberry are launched into space.
• 21 April: Minisat 1 (Spain). carries the Low Energy Gamma-Ray Imager (LEGRI).
• June 25: The unmanned Russian supply ship Progress collides with the Spektr module June 25 during a practice docking procedure, damaging Spektr's solar arrays and causing a loss of pressure and knocking out half of Mir's power.
• 30 June: The space probe NEAR Shoemaker travels toward its destination at asteroid 243 Ida, it passes by and images asteroid 253 Mathilde, a 66 by 48 km (41 by 30 mi) low-density object covered with several very large craters.
• 4 July: The NASA spacecraft Pathfinder lands on Mars in the Area Vallis region. Its mobile "rover" Sojourner is equipped with instruments to study soil and rocks, it beams back perfect color pictures nearly 120 million miles to the Jet Propulsion Laboratory at Pasadena, Calif., and its success bolsters arguments against the need for manned space exploration, but the spacecraft falls silent after 83 days.
• 6 August: It was reported that MWC480, a young star in the constellation Taurus, 450 Light years distant, has a gas-rich disk which looks like a possible "construction zone" for new planets.
• 7 August: A relief capsule docks with Mir August 7 following further mishaps, and Russian cosmonauts Vasily Tsibliev and Alexander Lazutkin land their Soyuz spacecraft in Kazakhstan on 14 August.
• 25 August: the United States launches the Advanced Composition Explorer (ACE) satellite, which will study the solar wind and cosmic rays from a stable point where the gravity from Earth and Sun are in balance.
• 15 October: The United States in conjunction with the European Space Agency launches the nuclear powered Cassini-Huygens mission, in many ways the most advanced space probe to date. Its goal is the study of Saturn and its satellites, with the Cassini orbiter to travel around the planet as the Huygens lander plunges into Saturn's atmosphere for a closer look. Along the way Cassini-Huygens will get a gravity boost from Jupiter, giving it a chance to report on that planet as it flies by.
• 21 October: Pictures of the Antennae galaxies, two intermeshed colliding galaxies, taken by the Hubble Space Telescope in 1996, were revealed to the public for the first time.

Asiasat 3 launched by the People's Republic of China, fails to achieve orbit, later successfully relaunched as HGS 1.

World's first university, where Aristotle and Socrates taught, is discovered in Athens.

Jupiter's moon Europa is found to be covered by liquid water under a thick outer layer of ice. Astronomers propose that Europa may harbor living organisms in the water flowing under the ice.

Comet Hale-Bopp, an extremely large comet first observed by amateur astronomers on July 22, 1995, makes it closest approach to Earth. At this time, it is visible with the naked eye. Scientists detect a host of organic compounds in its tail.

Astronomers from the University of Cambridge, England, discover the Antila Galaxy, a small member of the 30-some galaxies that constitute the Local Group which includes the Milky Way and Andromeda galaxies.

A study of data from the Compton Gamma Ray Observatory in space reveals jets of positrons (antielectrons) emanating from the center of the Milky Way Galaxy. They interact with ordinary electrons to produce radiation with a characteristic wavelength, which, expressed as energy, is 0.511 MeV, exactly the energy-mass of an electron.

1998

• 6 January: The Lunar Prospector spacecraft is launched into orbit around the Moon, and later confirms evidence for frozen water, in soil in permanently shadowed craters near the Moon's poles.
• 24 January: The U.S. space shuttle Endeavor docks with Russia's Mir space, carrying the last of seven U.S. astronauts to spend time on Mir. The Discovery space shuttle docks in June, scientific equipment is removed, and Mir is abandoned later in the year after its orbit is changed to make the 120-ton space station burn up in the atmosphere after 12 years in space.
• 17 February: Voyager 1 space probe becomes the most distant artificial object, reaching some 104 million km from Earth.
• 2 March: Data sent from the Galileo probe indicates that Jupiter's moon Europa has a liquid ocean under a thick crust of ice.
• 5 March: NASA announces that the Clementine probe orbiting the Moon has found enough water in polar craters to support a human colony and rocket fueling station.
• 5 March: NASA announces the choice of United States Air Force Lt. Col. Eileen Collins as commander of a future Space Shuttle Columbia mission to launch an X-ray telescope, making Collins the first woman commander of a space shuttle mission.
• 2 April: The United States launches TRACE (Transition Regions and Coronal Explorer), an Earth-orbiting satellite that will use its ultraviolet telescope to study magnetism in the Sun's corona.
• 8 April: Europe's Infrared Space Observatory has claimed to have discovered water around stars and planets. Water vapor in the atmosphere of Titan has also been reported.
• 21 April: Astronomers think they have discovered possible signs of a new family of planets orbiting a star 220 light-years away. Apparently the clearest evidence yet of worlds forming beyond our solar system. The dust structures are thought to be new solar systems forming around 3 sun-like stars.
  
  
• 25 May:In Cerro Paranal, Chile, the first mirror of the Very Large Telescope (VLT), operated by the European Southern Observatory (which includes Belgium, Denmark, France, Germany, Italy, the Netherlands, Sweden, and Switzerland), sees its "first light". When completed, the VLT will combine four mirrors, each 8.2 m (323 in.) in diameter. The telescopes are to be named and will be called - Antu, Kueyen, Melipal and Yepun.
  [Credit: ESO :: More…]
  
  
• 4 July: Japan launches Nozomi ("hope"), a.k.a. Planet B, which is originally planned for an orbit about Mars beginning in October 1999, from which it will study the Martian atmosphere and its interaction with the solar wind. Problems will develop and to conserve fuel the planned orbit about Mars is put off until 2004.
• 18 July: SINOSAT-1 was successfully launched from the Xichang Satellite Launch Center on onboard a Chinese LM-3B launch vehicle.
• 21 July: Astronaut Alan B. Shepard Jr. dies of leukemia at Monterey, Calif., at age 74.
• August:
  If you took a picture of the Sun at the same time each day, would it remain in the same position? The answer is no, and the shape traced out by the Sun over the course of a year is called an analemma. The Sun's apparent shift is caused by the Earth's motion around the Sun when combined with the tilt of the Earth's rotation axis. The Sun will appear at its highest point of the analemma during summer and at its lowest during winter. Analemmas created from different Earth latitudes would appear at least slightly different, as well as analemmas created at a different time each day. The analemma pictured to the left was built up by Sun photographs taken from 1998 August through 1999 August from Ukraine. The foreground picture from the same location was taken during the early evening in 1999 July.
  [Credit & Copyright: Vasilij Rumyantsev - Crimean Astrophysical Observatory]
• 23 Sepember: Scientists reported two more planets beyond our solar system. One in the constellation Cygnus and the other in Aquarius.
• 8 October: Astronomers reported sighting galaxies 12 billion light-years away using the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope.
• 29 October: Senator John Glenn, now 77, returns to orbit as a member of the space shuttle Discovery crew.
• 5 December: The United States launches SWAS (Submillimeter Wave Astronomy Satellite), a space-based radio telescope that will study the chemical composition of interstellar gas clouds, the homes of new stars.

Construction started on the International Space Station.

Two groups, one headed by Saul Perlmutter of Lawrence Berkeley National Laboratory in California and the other led by Brian P Schmidt of the Mount Stromlo Observatory near Canberra, Australia, discover by observing distant Type 1 supernovae that the universe's expansion is speeding up. This conclusion comes from comparing the distance to the supernovae revealed by two different measures, redshift and brightness. Because redshift distances are based on how fast the universe is expanding, when the brightness measurements (independent of expansion) reveal farther distances than redshifts do, the implication is that the universe expands more quickly at greater distances. The astronomers postulate that some force is accelerating expansion, which before this had been expected to slow down. The still unknown force is called dark energy.

United States launched the Mars Climate Orbiter and Mars Polar Lander, part of the Mars Orbiter '98 mission.

Data from satellite-borne X-ray telescopes combined with optical data from the Keck II telescope reveal the largest known explosion since the big bang, a burst of gamma rays as luminous for a second or two as the rest of the universe. The cause of the explosion remains unknown.

The heaviest quark predicted, "Top", is found.

A burst of X rays from the object SGR 1900+14 reveals that the object is the first known magnetar (predicted by theorists since 1992), a type of neutron star that produces the most intense magnetic fields known in the universe.

The Galileo spacecraft helps scientists to discover the origins of Jupiter's rings.

Astronomers use images produced by the Galileo space probe during its orbits about Jupiter to determine that the giant planet has four separate rings instead of only one. Each ring is produced by the passage of a shepherding moon. The shepherds are Metis, Adrastea, Amalthea, and Thebe, all among the smaller satellites of Jupiter.

Japanese researchers find evidence that neutrinos (possible candidate as "dark matter") may have mass.

Gamma ray bursts proven to originate in distant galaxies, not our own, thus deepening the mystery of their origin and power.

Raymond Davis publishes the final results of the detection of neutrinos from the Sun with the detector at the Homestake Gold Mine in South Dakota, and concludes that fewer neutrinos have been detected than predicted by current theories.

In the Gran Sasso Tunnel, Italy, astronomers from Italy and Germany begin operations of the Gallium Neutrino Observatory, using 100 tons of gallium chloride. As in the earlier GALLEX experiment, they study solar neutrinos observed when the neutrinos strike gallium atoms and transmute them to germanium.

1999

• 23 January: the Robotic Optical Transient Search Experiment (ROTSE) near Los Alamos National Laboratory in New Mexico observes the first optical image associated with a gamma-ray burst. The light from GRB 990123 is captured just 22 seconds after the explosion is recognized by gamma-ray detecting satellites. GRB 990123 is also the most powerful gamma-ray burst observed to this date. Current theory holds that the gamma-ray bursts occur when a giant star collapses into a black hole, sending out jets that produce the bursts as they strike nearby gas or dust.
• 7 February: the United States launches the space probe Stardust. Its mission is the capture and return to Earth of dust from comet Wild 2, which it is scheduled to reach in January 2004. Stardust is expected to parachute the samples back to Earth in 2006.
• 11 February: Pluto, a dwarf planet with an eccentric orbit, moves further from the Sun than Neptune. It had been nearer than Neptune since 1979, and will become again in 2231.
• 23 February: ARGOS. Advanced Research and Global Observations Satellite, carrying the Unconventional Stellar Aspect (USA) experiment.
• 4 March: WIRE. Wide Field Infrared Explorer. Failed because of an electronic failure which lead to destroying the cooling system for the IR camera. Some optical astronomy is done with its 5-cm optical guidance telescope, notably stellar seismology.
• March: Mars Global Surveyor enters its orbit about the planet Mars, beginning a study that will last for at least one Mars year of 687 days. Among its first discoveries is that fossil magnetism, which can be detected from space, indicates that 4,000,000,000 years ago Mars had active tectonic plates, similar to those known on Earth. It also finds additional evidence that water once flowed over the Martian surface.
• 15 April: Astronomers announced that 3 planets had been detected orbiting the star Upsilon Andromedae some 44 light-years away.
• 28 April: ABRIXAS (Germany). "A Broad-Band Imaging All-Sky Survey". X-ray satellite. Failed during second day in orbit because of power supply failure.
• 24 June: The United States along with Canada and France launches FUSE (Far Ultraviolet Spectroscopic Explorer), a space-based telescope that will explore the universe at wavelengths slightly longer than X rays. FUSE fills a gap in astronomers' coverage of the electromagnetic spectrum.
• 23 July: The space shuttle Columbia, piloted by Col. Eileen Collins, puts the Chandra X-Ray Observatory, a space-based telescope that will become among the most successful of NASA's observatories. Developed as Advanced X-ray Astrophysics Facility (AXAF). This 5,200 kg satellite is a 11.2 meter long, 4.2 meter diameter observatory, and should observe cosmic X-ray sources, during a scheduled active lifetime of 5 years.
• 31 July: NASA intentionally crashes the Lunar Prospector spacecraft into the Moon, thus ending its mission to detect frozen water on the lunar surface.
• 11 August: A total solar eclipse is seen in Europe and Asia.
• October: NASA received a set-back when the Mars Climate Orbiter is lost.
• 29 November: Astronomers reported finding 6 planets orbiting sun-like stars as close as 65 light years from Earth.
• 3 December: NASA loses radio contact with the Mars Polar Lander, moments before the spacecraft enters the Martian atmosphere.
• 10 December: The European Space Agency launches the X-Ray Multi-Mirror Telescope, generally known as XXM-Newton. This is the most powerful X-ray detector ever put into space. XXM-Newton has three X-ray telescopes, two X-ray spectroscopes, and an optical telescope. Its orbit about Earth takes it a third of the way to the Moon, giving it long periods of time for observation of stars, pulsars, active galaxies, and black holes.
• 14 December 14: REOSC, the Optical Department of the SAGEM Group, finished the polishing of the fourth 8.2-m main mirror for the Very Large Telescope (VLT) of the European Southern Observatory. The mirror was today delivered to ESO at a ceremony at the REOSC factory in Saint Pierre du Perray, just south of Paris. The precision of the form of the mirror that was achieved during the polishing process is 8.5 nanometer (1 nanometer = 1 millionth of a millimetre) over the optical surface. This exceptional value corresponds to an optical resolution (theoretical image sharpness) of 0.03 arcseconds in the visible spectrum. This corresponds to distinguishing two objects separated by only 15 cm at a distance of 1000 km and will allow to detect astronomical objects that are 10,000 million times fainter than what can be perceived with the unaided eye.
• 18 December: NASA launches into orbit the Terra platform carrying five Earth Observation instruments, including ASTER, CERES, MISR, MODIS and MOPITT.

A comparison of the luminosity and red shift of remote supernovas indicates that the Universe is expanding faster and faster.

Geoffrey W. Marcy of San Francisco State University and Robert Noyes of the Harvard-Smithsonian Center for Astrophysics discover that there are at least three planets orbiting the star Upsilon Andromedae, a star about 44 light-years from Earth. Two planets are much larger than Jupiter, while the third, about 3/4 the size of Jupiter, is orbiting the star so closely that its period is only 4.6 Earth days; thus, this first nonsolar system of planets to be discovered is not much like our familiar solar system.

Gregory W. Henry becomes the first astronomer to observe the periodic dimming of light from star HD 209458; this is caused by an extrasolar planet orbiting the star.

The real Hubble Constant, the speed at which the universe is expanding, is calculated.

The Sloan Digital Sky Survey begins. It uses the largest electronic camera ever built to map millions of galaxies and other objects visible from our galaxy.

Philip Lucas and Patrick Roche discover 13 free-floating extrasolar "planets" in the Orion Nebula. Since these small bodies are not in orbit about a star, however, they will later be termed "planetars" or "sub-brown dwarfs." They are not brown dwarfs because they have masses below 13 times that of Jupiter. At a mass of 13 Jupiters, bodies produce limited nuclear reactions, making brown dwarfs low-level cousins of stars.

United States launched Deep Space 2.

The Hobby-Eberly telescope, dedicated primarily to spectroscopy, begins operation in October at the McDonald Observatory in the Davis Mountains of Texas. It has the world's largest primary mirror at 11 m (433 in.), but is considered the world's third largest telescope at this time (Keck 1 and 2 are first and second) because only 9.2 m (362 in.) of the surface is available for use at any one time.

NEAR (Near Earth Asteroid Rendezvous) spacecraft orbits an asteroid (Eros) for the first time.

During this year the Gemini North and Subaru telescopes begin operations on Mauna Kea, Hawaii. Gemini is 8 metres and will have an exact twin in the Southern Hemisphere. Subaru is 8.3 metres and is the largest telescope mirror to this time cast from a single piece of glass.

2000

• 10 February: Astro-E (Japan). Unfortunately, the spacecraft got lost during launch. Designed for a 2-year operational life, it carried a complex X-ray observatory, equipped with 4 foiled telescopes with imaging spectrometers, 1 foiled telescope with micro-calorimeter, and one hard X-ray detector.
• 25 August: In West Virginia the new $75 million Robert C. Boyd Green Bank Telescope, the world's largest fully steerable radio telescope, was dedicated following almost 10 years of construction.
• 9 October: HETE-2. High Energy Transient Explorer to detect GRBs and observe in X-ray and Gamma ray radiation.

The space shuttle Endeavor set out on its radar topography mission of the Earth.

The NEAR Shoemaker spacecraft sends back images of the asteroid Eros, and makes a historic first landing on an asteroid.