PIA00404: Moon - North Polar Mosaic, Color.

20th-21st Century Planetary Discoveries

  Expand   Kuiper Belt and Oort Cloud:

  • 1943 – Astronomer Kenneth Edgeworth suggests that a reservoir of comets exists beyond the planets
  • 1950 – Astronomer Jan Oort theorizes that a vast population of comets may exist on the distant edges of our solar system
  • 1951 – Astronomer Gerald Kuiper predicts the existence of a belt of ice objects just beyond the orbit of Neptune
  • 1992 – After five years of searching, astronomer David Jewitt and Jane Luu discover the first Kuiper Belt object, 1992 QBI
  • 2002 – Scientists using the 48-inch Oschin telescope at Palomar Observatory find Quasar
  • 2004 – Astronomers using the Palomar 48-inch Oschin telescope announce the discovery of Sedna (2003 VB12)
  • 2005 – Astronomers announce the discovery of 2003 UB 313, a distant icy solar system body that has a small moon

  Expand   Comets:

  • 1986 – An international fleet of five spacecraft converges on comet Halley as it makes its regular (about every 76 years) pass through the inner solar system
  • 1994 – In the first observed planetary impact by a comet, awed scientists watch as fragments of comet Shoemaker-Levy 9 smash into Jupiter’s atmosphere
  • 2001 – Deep Space 1 flies by and photographs comet Borrelly
  • 2004 – NASA’s Stardust spacecraft snaps photos and collects dust samples from comet Wild 2 during the closest-ever flyby of a comet nucleus. The photographs show jets of dust and a rugged, textured surface
  • 2005 – The Deep Impact impactor collides with comet Tempel 1 to reveal the interior of the nucleus

  Expand   Pluto and Charon:

  • 1930 – Clyde Tombaugh discovers Pluto
  • 1977-1999 – Pluto’s lopsided orbit brings it slightly closer to the Sun than Neptune. It will be at least 230 years before Pluto again gets another 20-year stint as the eighth planet
  • 1978 – American astronomers James Christy and Robert Harrington discover Pluto’s only moon, Charon
  • 1988 – Astronomers discover that Pluto has an atmosphere
  • 2010-2025 – Pluto’s atmosphere may freeze and collapse as the planet moves farther from the Sun

  Expand   Neptune:

  • 1984 – Astronomers find evidence for the existence of a ring system, but the rings are clearly not uniform in density
  • 1989 – Voyager 2 becomes the first and only spacecraft to visit Neptune, passing about 4,800 kilometers (2,983 miles) above the planet’s north pole
  • 2003 – Using improved observing techniques, astronomers discover five new moons orbiting Neptune
  • 2001 – Neptune completes its first 165-year orbit of the Sun since its discovery in 1846

  Expand   Uranus:

  • 1948 – A new moon, Miranda, is discovered
  • 1977 – Scientists discover Uranus’ faint ring system while watching a distant star pass behind the planet
  • 1986 - Voyager 2 becomes the first, and still the only, spacecraft to visit Uranus, discovering 10 moons and several additional rings during its flyby
  • 1997-1999 – Astronomers discover more tiny moons orbiting Uranus

  Expand   Saturn:

  • 1979 – Pioneer 11 is the first spacecraft to reach Saturn, flying within 22,000 kilometers (13,700 miles) of the ringed planet’s cloud tops
  • 1981 – Using Saturn’s powerful gravity as an interplanetary “slingshot,” Voyager 2 is placed on a path toward Uranus, then Neptune, then out of the solar system
  • 1994 – The Hubble Space Telescope finds evidence of surface features beneath the hazy atmosphere of Saturn’s largest moon, Titan
  • 2004 – After a seven-year journey, the Cassini-Huygens spacecraft becomes the first spacecraft to orbit Saturn; 76 orbits of Saturn and 45 Titan flybys are planned for the four-year mission
  • 2005 – The Huygens probe successfully lands on Titan, returning images of the complex surface

  Expand   Galilean Moons of Jupiter:

  • 1979 – Voyager 1 photographs an erupting volcano on Io: the first ever seen anywhere but on Earth
  • 1979-2000 – Using data from the Voyager and Galileo spacecraft, scientists gather strong evidence of an ocean beneath the icy crust of Europa; Galileo data indicate possible oceans on Ganymede and Callisto
  • 2003 – The Galileo mission ends with the spacecraft deliberately descending into Jupiter’s atmosphere. In the same year, scientists discover 23 new moons of Jupiter

  Expand   Jupiter:

  • 1973 – Pioneer 10 becomes the first spacecraft to cross the asteroid belt and fly past Jupiter
  • 1979 – Voyager 1 and 2 discover Jupiter’s faint rings, several new moons, and volcanic activity on Io’s surface
  • 1994 – Astronomers watch pieces of comet Shoemaker-Levy 9 collide with Jupiter
  • 1995-2003 – The Galileo spacecraft conducts extended observations of Jupiter and its moons and rings

  Expand   Moons of the Solar System:

  • 1969 – Astronaut Neil Armstrong is the first if 12 humans to walk on the surface of the Moon
  • 1980 – Voyager 1 instruments detect signs of surface features beneath the hazy atmosphere of Saturn’s largest moon, Titan
  • 2000-2005 – Since the beginning of the year 2000, 84 of the 153 known moons of the solar system have been discovered. Jupiter’s known moons have increased from 18 to 62. Saturn’s known moon have jumped from 18 to 47. Uranus’ moon count has gone from 21 to 27, and Neptune’s knows moon have increased in number from 8 to 13

  Expand   Meteors and Meteorites:

  • 1908 (Tunguska), 1947 (Sikote Alin), 1969 (Allende and Murchison), 1976 (Jilin) – Important 20th-century meteorite falls
  • 1969 – Discovery of meteorites in a small area of Antarctica leads to annual expeditions by U.S. and Japanese teams
  • 1982-1983 – Meteorites from the Moon and Mars are identified in Antarctic collections
  • 1996 – A team of NASA scientists suggests that Martian meteorite ALH 84001 may contain evidence of microfossils from Mars
  • 2005 – NASA’s Mars Exploration Rover Opportunity finds an iron meteorite on Mars

  Expand   Asteroids:

  • 1991-1994 – On its way to Jupiter, the Galileo spacecraft takes the first close-up images of an asteroid (Gaspra) and discovers the first moon (later named Dactyl) orbiting an asteroid (Ida)
  • 1997-2000 – NEAR Shoemaker spacecraft flies by Mathilde and orbits and lands on Eros

  Expand   Mars:

  • 1965 – NASA’s Mariner 4 sends back 22 photos of Mars, the world’s first close-up photos of a planet beyond Earth
  • 1976 – Viking 1 and 2 make the first, and still one of the few, successful landings on the surface of Mars
  • 1997 – Mars Pathfinder lands and dispatches Sojourner, the first wheeled rover to explore the surface of another planet
  • 2004 – Twin Mars Exploration Rovers named Spirit and Opportunity land on Mars and find the strongest evidence yet obtained that the red planet once had long-standing bodies of water

  Expand   Earth's Moon:

  • 1959-1960 – Luna 1,2, and 3 are the first to by, impact, and photograph the far side of the Moon
  • 1966 – Surveyor 1 makes the first soft landing on the Moon
  • 1969 – Astronaut Neil Armstrong is the first of 12 humans to walk on the lunar surface
  • 1996 – Clementine data indicate water ice at the south pole
  • 1998 – Lunar Prospector data indicate that ice exists at both lunar poles

  Expand   Earth:

  • 1960 – NASA launches Tiros, the first weather satellite
  • 1972 – Landsat 1 is launched, the first in a series that continues today. The images are used in agriculture, geology, forestry, regional planning, mapping, and global change research
  • 1992 – Topex/Poseidon, a U.S.-France mission, begins measuring sea-surface height; the data revolutionize understanding of the ocean’s role in weather and climate
  • 1997 – The U.S.-Japan Tropical Rainfall Measuring Mission is launched. It includes the first space borne instrument to provide three-dimensional maps of storm structure
  • 1999-2005 – A series of Earth-observing satellites is launched to provide complementary data sets on Earth’s system: Terra (land, oceans, atmosphere), Aqua (water cycle), Aura (atmospheric chemistry), and Gravity Recovery and Climate Experiment (gravity fields). Planned are CloudSat (clouds) and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations mission (aerosols, clouds)

  Expand   Venus:

  • 1962 – Mariner 2 reaches Venus and reveals the planet’s extreme surface temperatures. It is the first spacecraft to send back information from another planet
  • 1970 – Venera 7 sends back 23 minutes of data from the surface of Venus. It is the first spacecraft to successfully land on another planet
  • 1990-1994 – The Magellan spacecraft, in orbit around Venus, uses radar to map 98 percent of the planet’s surface

  Expand   Mercury:

  • 1965 – Though it was thought for centuries that the same side of Mercury always faced the Sun, astronomers find the planet rotates three times for every two orbits
  • 1974-1975 – Mariner 10 photographs roughly half of Mercury’s surface in three flybys
  • 1991 – Scientists using Earth-based radar find signs of ice tucked in permanently shadowed areas of craters in Mercury’s polar regions
  • 2004 – MESSENGER launches on a mission to make the most comprehensive study yet of the innermost planet

  Expand   Our Star – The Sun:

  • 1994 – The Ulysses spacecraft makes history as it makes the first observations of the Sun’s Polar Regions, which cannot be studied from Earth