1995 August 1
Crossing The Ring Plane
Credit: NASA, Hubble Space Telescope
"I do not know what to say in a case so surprising, so unlooked for and so novel." announced Galileo when Saturn's rings appeared to vanish in 1612. In fact, every 15 years Saturn's rings seem to almost disappear as viewed from the Earth. This happens just as the orbiting Earth crosses the plane of Saturn's rings. The edge on perspective temporarily robs astronomers of a spectacular sight, however, the ring plane crossing affords them the opportunity to measure the rings' thickness and search for undiscovered moons. In this image of Saturn, produced on May 22, 1995 by NASA's Hubble Space Telescope, two of Saturn's known moons are visible as star like objects to the left of the planet.
For more information about the ring plane crossing see the Saturn Ring Plane Crossing web page .
Crossing The Ring Plane
Credit: NASA, Hubble Space Telescope
"I do not know what to say in a case so surprising, so unlooked for and so novel." announced Galileo when Saturn's rings appeared to vanish in 1612. In fact, every 15 years Saturn's rings seem to almost disappear as viewed from the Earth. This happens just as the orbiting Earth crosses the plane of Saturn's rings. The edge on perspective temporarily robs astronomers of a spectacular sight, however, the ring plane crossing affords them the opportunity to measure the rings' thickness and search for undiscovered moons. In this image of Saturn, produced on May 22, 1995 by NASA's Hubble Space Telescope, two of Saturn's known moons are visible as star like objects to the left of the planet.
For more information about the ring plane crossing see the Saturn Ring Plane Crossing web page .
1995 August 2
Jupiter's Rings
Credit: NASA, Voyager Project
Astronomers using NASA's Voyager spacecraft to search for a ring system around Jupiter discovered these faint rings in 1979. Unlike Saturn's bright rings which are composed of chunks of rock and ice, Jupiter's rings appear to consist of fine particles of dust. One possibility is that the dust is produced by impacts with Jupiter's inner moons. This false color image has been computer enhanced.
The gas giant planets, Jupiter, Saturn, Uranus, and Neptune are all known to have rings. For more information about planetary ring systems see the Planetary Rings Node.
Jupiter's Rings
Credit: NASA, Voyager Project
Astronomers using NASA's Voyager spacecraft to search for a ring system around Jupiter discovered these faint rings in 1979. Unlike Saturn's bright rings which are composed of chunks of rock and ice, Jupiter's rings appear to consist of fine particles of dust. One possibility is that the dust is produced by impacts with Jupiter's inner moons. This false color image has been computer enhanced.
The gas giant planets, Jupiter, Saturn, Uranus, and Neptune are all known to have rings. For more information about planetary ring systems see the Planetary Rings Node.
1995 August 3
Io: A Volcanic Moon
Credit: NASA, Voyager Project
In 1610, Galileo turned his telescope to the heavens and discovered that the planet Jupiter had four bright moons. The innermost of these Galilean moons, Io, turned out to be one of the most exotic objects in the solar system. About the size of the earth's moon, Io is covered with volcanoes, many of which are currently active. The material expelled in the volcanic eruptions may contain compounds of Sulfur which take on a variety of colors and could account for its mottled, "pizza-like" appearance.
For a report of a recent eruption of an Io volcano, see the NASA Infrared Telescope Facility press release and photo .
Io: A Volcanic Moon
Credit: NASA, Voyager Project
In 1610, Galileo turned his telescope to the heavens and discovered that the planet Jupiter had four bright moons. The innermost of these Galilean moons, Io, turned out to be one of the most exotic objects in the solar system. About the size of the earth's moon, Io is covered with volcanoes, many of which are currently active. The material expelled in the volcanic eruptions may contain compounds of Sulfur which take on a variety of colors and could account for its mottled, "pizza-like" appearance.
For a report of a recent eruption of an Io volcano, see the NASA Infrared Telescope Facility press release and photo .
1995 August 4
Closeup of an Io Volcano
Credit: NASA, Voyager Project, Copyright Calvin J. Hamilton
In 1979, one of NASA's Voyager spacecraft made a spectacular and unexpected discovery. Io, the innermost Galilean moon of Jupiter, was covered with volcanoes and some of them were erupting! In all, Voyager 1 observed nine volcanic eruptions during its encounter with the moon. When Voyager 2 flew past four months later it was able to confirm that at least six of them were still erupting. This Voyager image of Ra Patera, a large shield volcano, shows colorful flows up to about 200 miles long emanating from the dark central volcanic vent.
For more information about volcanism on Io, see Calvin J. Hamilton's Io page
Closeup of an Io Volcano
Credit: NASA, Voyager Project, Copyright Calvin J. Hamilton
In 1979, one of NASA's Voyager spacecraft made a spectacular and unexpected discovery. Io, the innermost Galilean moon of Jupiter, was covered with volcanoes and some of them were erupting! In all, Voyager 1 observed nine volcanic eruptions during its encounter with the moon. When Voyager 2 flew past four months later it was able to confirm that at least six of them were still erupting. This Voyager image of Ra Patera, a large shield volcano, shows colorful flows up to about 200 miles long emanating from the dark central volcanic vent.
For more information about volcanism on Io, see Calvin J. Hamilton's Io page
1995 August 5
Geysers on Triton
Credit: NASA, Voyager Project, Copyright Calvin J. Hamilton
In August of 1989 NASA's Voyager 2 spacecraft passed by Neptune, the most distant of the solar system's gas giant planets. Its encounter with Neptune climaxed with its closest approach to Neptune's largest moon Triton. From a distance of about 24,000 miles the robot space probe surveyed Triton's surface, whose temperature averages nearly -400 degrees Fahrenheit, and discovered surprising evidence of a complex and active world. For example, the prominent dark streaks in this image seem to come from small volcanoes and may consist of nitrogen frost mixed with organic compounds ejected during geyser-like eruptions.
For more information about Triton, see Calvin J. Hamilton's Triton page .
Geysers on Triton
Credit: NASA, Voyager Project, Copyright Calvin J. Hamilton
In August of 1989 NASA's Voyager 2 spacecraft passed by Neptune, the most distant of the solar system's gas giant planets. Its encounter with Neptune climaxed with its closest approach to Neptune's largest moon Triton. From a distance of about 24,000 miles the robot space probe surveyed Triton's surface, whose temperature averages nearly -400 degrees Fahrenheit, and discovered surprising evidence of a complex and active world. For example, the prominent dark streaks in this image seem to come from small volcanoes and may consist of nitrogen frost mixed with organic compounds ejected during geyser-like eruptions.
For more information about Triton, see Calvin J. Hamilton's Triton page .
1995 August 6
Liftoff of Space Shuttle Columbia
Credit: NASA, Kennedy Space Center
On April 12, 1981, space flight entered a new era with the first launch of Space Shuttle Columbia, shown above. NASA's Space Shuttles land like a normal plane, carry a heavy cargo, carry a large crew, make use of cheap solid fuel, and are reusable. Previous to this flight, no manned orbiting space ship had ever landed on a runway. Space Shuttles now are the flagships and the workhorses of NASA's space going rockets.
For more information about NASA's Space Shuttle missions, see the NASA Space Shuttle Launches page.
Liftoff of Space Shuttle Columbia
Credit: NASA, Kennedy Space Center
On April 12, 1981, space flight entered a new era with the first launch of Space Shuttle Columbia, shown above. NASA's Space Shuttles land like a normal plane, carry a heavy cargo, carry a large crew, make use of cheap solid fuel, and are reusable. Previous to this flight, no manned orbiting space ship had ever landed on a runway. Space Shuttles now are the flagships and the workhorses of NASA's space going rockets.
For more information about NASA's Space Shuttle missions, see the NASA Space Shuttle Launches page.
1995 August 7
Night Launch of Endeavour
Credit: NASA, Kennedy Space Center
Space Shuttle Endeavour thunders off into orbit in a rare night launch. This March 1995 mission is most famous for operating the set of astronomical telescopes known as Astro-2. Astro-2's telescopes observed the universe in ultraviolet light - light so blue humans by themselves can't see it. Astro-2 measured the amount of ultraviolet light emitted by several interesting stars, galaxies, planets, and QSOs. Analysis of data from this NASA mission has yielded the first clear detection of helium created during the beginning of the universe.
For more information about NASA's Space Shuttle missions, see the NASA Space Shuttle Launches page.
Night Launch of Endeavour
Credit: NASA, Kennedy Space Center
Space Shuttle Endeavour thunders off into orbit in a rare night launch. This March 1995 mission is most famous for operating the set of astronomical telescopes known as Astro-2. Astro-2's telescopes observed the universe in ultraviolet light - light so blue humans by themselves can't see it. Astro-2 measured the amount of ultraviolet light emitted by several interesting stars, galaxies, planets, and QSOs. Analysis of data from this NASA mission has yielded the first clear detection of helium created during the beginning of the universe.
For more information about NASA's Space Shuttle missions, see the NASA Space Shuttle Launches page.
1995 August 8
Columbia Waits, Discovery Launches
Credit: NASA, Kennedy Space Center
Space Shuttle Discovery launches while the Space Shuttle Columbia is readied for a future mission. Space shuttles are launched from the Kennedy Space Center in Florida. At this date there are four operating space shuttles: Atlantis, Columbia, Discovery, and Endeavour. This mission is most famous for carrying the Hubble Space Telescope into orbit. The Hubble Space Telescope is the largest public optical telescope ever to operate in orbit, and because it is above Earth's atmosphere it's photographs are more clear than any ground based telescope. Hubble continues to make fundamental discoveries about planets, stars, galaxies, comets, QSOs, and the universe we live in.
Columbia Waits, Discovery Launches
Credit: NASA, Kennedy Space Center
Space Shuttle Discovery launches while the Space Shuttle Columbia is readied for a future mission. Space shuttles are launched from the Kennedy Space Center in Florida. At this date there are four operating space shuttles: Atlantis, Columbia, Discovery, and Endeavour. This mission is most famous for carrying the Hubble Space Telescope into orbit. The Hubble Space Telescope is the largest public optical telescope ever to operate in orbit, and because it is above Earth's atmosphere it's photographs are more clear than any ground based telescope. Hubble continues to make fundamental discoveries about planets, stars, galaxies, comets, QSOs, and the universe we live in.
1995 August 9
Challenger Launches Spacelab 2
Credit: NASA, Kennedy Space Center
Space Shuttle Challenger jumps off the launch pad in 1985 to begin a successful mission. The main purpose of this mission was to test a new space based laboratory named Spacelab 2. Spacelab 2 takes advantage of the effectively weightless conditions in orbit to carry out experiments in areas such as astronomy, physics, life science, materials science, and atmospheric physics. Challenger and her crew were lost in 1986 when a booster failure resulted in the breakup of the vehicle. Previously, Challenger and her crews flew nine successful Space Shuttle missions and made significant contributions to America's scientific growth.
Challenger Launches Spacelab 2
Credit: NASA, Kennedy Space Center
Space Shuttle Challenger jumps off the launch pad in 1985 to begin a successful mission. The main purpose of this mission was to test a new space based laboratory named Spacelab 2. Spacelab 2 takes advantage of the effectively weightless conditions in orbit to carry out experiments in areas such as astronomy, physics, life science, materials science, and atmospheric physics. Challenger and her crew were lost in 1986 when a booster failure resulted in the breakup of the vehicle. Previously, Challenger and her crews flew nine successful Space Shuttle missions and made significant contributions to America's scientific growth.
1995 August 10
The Orbiting Hubble Space Telescope
Credit: NASA, Space Telescope Scientific Institute
The Hubble Space Telescope (HST) is the largest orbiting public optical telescope in history. Its 2.4 meter diameter reflecting mirror and its perch above Earth's atmosphere allow it to create exceptionally sharp images. Originally launched in 1990, HST optics were repaired to their intended accuracy in 1993 by the first of several regular servicing missions. Astronomers using HST continue to make numerous monumental scientific discoveries, including new estimates of the age of our universe, previously unknown galaxies, evidence of massive black holes in the centers of galaxies, previously unknown moons, and a better understanding of physical processes in our universe.
The Orbiting Hubble Space Telescope
Credit: NASA, Space Telescope Scientific Institute
The Hubble Space Telescope (HST) is the largest orbiting public optical telescope in history. Its 2.4 meter diameter reflecting mirror and its perch above Earth's atmosphere allow it to create exceptionally sharp images. Originally launched in 1990, HST optics were repaired to their intended accuracy in 1993 by the first of several regular servicing missions. Astronomers using HST continue to make numerous monumental scientific discoveries, including new estimates of the age of our universe, previously unknown galaxies, evidence of massive black holes in the centers of galaxies, previously unknown moons, and a better understanding of physical processes in our universe.
1995 August 11
The Compton Gamma Ray Observatory
Credit: NASA, Compton Gamma Ray Observatory Science Support Center
The Compton Gamma Ray Observatory (CGRO) was the most massive instrument ever launched by a NASA Space Shuttle and continues to revolutionize gamma-ray astronomy. This orbiting observatory sees the sky in gamma-ray photons - light so blue humans can't see it. These photons are blocked by the Earth's atmosphere from reaching the Earth's surface. Results from CGRO have shown the entire universe to be a violent and rapidly changing place - when viewed in gamma-rays. Astronomers using CGRO data continue to make monumental discoveries, including showing that mysterious flashes of gamma-rays are much more powerful than previously imagined, discovery of a whole new class of QSO, and discovery of objects so strange that astronomers can't yet figure out what they are.
The Compton Gamma Ray Observatory
Credit: NASA, Compton Gamma Ray Observatory Science Support Center
The Compton Gamma Ray Observatory (CGRO) was the most massive instrument ever launched by a NASA Space Shuttle and continues to revolutionize gamma-ray astronomy. This orbiting observatory sees the sky in gamma-ray photons - light so blue humans can't see it. These photons are blocked by the Earth's atmosphere from reaching the Earth's surface. Results from CGRO have shown the entire universe to be a violent and rapidly changing place - when viewed in gamma-rays. Astronomers using CGRO data continue to make monumental discoveries, including showing that mysterious flashes of gamma-rays are much more powerful than previously imagined, discovery of a whole new class of QSO, and discovery of objects so strange that astronomers can't yet figure out what they are.
1995 August 12
Atlantis Landing
Credit: NASA, Kennedy Space Center
Space Shuttle Atlantis lands at Edwards Air Force Base in California. The Space Shuttle is the first orbital space vehicle to land on a runway like an airplane. Space Shuttles sometimes have the option of landing in White Sands, New Mexico or at the Shuttle Landing Facility at the Kennedy Space Center in Florida. The runways the shuttles land on are among the longest in the world. Shuttles that do not land in Florida must generally be strapped to the back of a 747 airplane and flown back.
Atlantis Landing
Credit: NASA, Kennedy Space Center
Space Shuttle Atlantis lands at Edwards Air Force Base in California. The Space Shuttle is the first orbital space vehicle to land on a runway like an airplane. Space Shuttles sometimes have the option of landing in White Sands, New Mexico or at the Shuttle Landing Facility at the Kennedy Space Center in Florida. The runways the shuttles land on are among the longest in the world. Shuttles that do not land in Florida must generally be strapped to the back of a 747 airplane and flown back.
1995 August 13
The Sun Erupts
Credit: NASA, Skylab
The sun was captured in 1973 throwing one of the largest eruptive prominences ever recorded. Sol, our sun, is a normal star. It formed about 5 billion years ago, and will last about another 5 billion years. The sun will never explode, and a solar flare will never destroy the earth. Eventually the sun will become a white dwarf star. The sun is made of mostly hydrogen and helium. The sun's center is so hot that when hydrogen nuclei collide, they stick together and release energy - a process called nuclear fusion No one knows why the center of the sun emits so few neutrinos.
The Sun Erupts
Credit: NASA, Skylab
The sun was captured in 1973 throwing one of the largest eruptive prominences ever recorded. Sol, our sun, is a normal star. It formed about 5 billion years ago, and will last about another 5 billion years. The sun will never explode, and a solar flare will never destroy the earth. Eventually the sun will become a white dwarf star. The sun is made of mostly hydrogen and helium. The sun's center is so hot that when hydrogen nuclei collide, they stick together and release energy - a process called nuclear fusion No one knows why the center of the sun emits so few neutrinos.
1995 August 14
Mercury: Closest Planet to the Sun
Credit: NASA, Mariner 10
This picture was compiled from images taken by the NASA spacecraft Mariner 10 which flew by the planet three times in 1974. Mercury is the closest planet to the Sun, the second hottest planet (Venus gets hotter), and the second smallest planet (Pluto is smaller). Mercury rotates so slowly that one day there - "day" meaning the normal time it takes from sunset to sunset - lasts 176 days on Earth. It is difficult to see Mercury not because it is dim but because it always appears near the Sun, and is therefore only visible for a short time just after sunset or just before sunrise. Mercury is made of rocky material like Earth. No one knows why Mercury has the magnetic field that it does.
Mercury: Closest Planet to the Sun
Credit: NASA, Mariner 10
This picture was compiled from images taken by the NASA spacecraft Mariner 10 which flew by the planet three times in 1974. Mercury is the closest planet to the Sun, the second hottest planet (Venus gets hotter), and the second smallest planet (Pluto is smaller). Mercury rotates so slowly that one day there - "day" meaning the normal time it takes from sunset to sunset - lasts 176 days on Earth. It is difficult to see Mercury not because it is dim but because it always appears near the Sun, and is therefore only visible for a short time just after sunset or just before sunrise. Mercury is made of rocky material like Earth. No one knows why Mercury has the magnetic field that it does.
1995 August 15
Venus: Earth's Sister Planet
Credit: NASA, Galileo, Copyright Calvin J. Hamilton
This picture in visible light was taken by the Galileo spacecraft. Venus is very similar to Earth in size and mass - and so is sometimes referred to as Earth's sister planet - but Venus has a quite different climate. Venus' thick clouds and closeness to the Sun (only Mercury is closer) make it the hottest planet - much hotter than the Earth. Humans could not survive there, and no life of any sort has ever been found. When Venus is visible it is usually the brightest object in the sky after the Sun and the Moon. More than 20 spacecraft have visited Venus including Venera 9, which landed on the surface, and Magellan, which used radar to peer through the clouds and make a map of the surface. There are still many things about Venus's unusual atmosphere that astronomers don't understand.
Venus: Earth's Sister Planet
Credit: NASA, Galileo, Copyright Calvin J. Hamilton
This picture in visible light was taken by the Galileo spacecraft. Venus is very similar to Earth in size and mass - and so is sometimes referred to as Earth's sister planet - but Venus has a quite different climate. Venus' thick clouds and closeness to the Sun (only Mercury is closer) make it the hottest planet - much hotter than the Earth. Humans could not survive there, and no life of any sort has ever been found. When Venus is visible it is usually the brightest object in the sky after the Sun and the Moon. More than 20 spacecraft have visited Venus including Venera 9, which landed on the surface, and Magellan, which used radar to peer through the clouds and make a map of the surface. There are still many things about Venus's unusual atmosphere that astronomers don't understand.
1995 August 16
Uranus: The Tilted Planet
Credit: NASA, Voyager 2
This picture was snapped by the Voyager 2 spacecraft in 1986 - the only spacecraft ever to visit Uranus. Uranus is the third largest planet after Jupiter and Saturn. Uranus has many moons and a ring system. Uranus is composed mostly of liquid water, methane and ammonia, surrounded by a thick gas atmosphere of mostly hydrogen and helium. Uranus is peculiar in that its rotation axis is greatly tilted and sometimes points near the sun. It remains an astronomical mystery why Uranus' axis is so tilted. Uranus and Neptune are very similar.
Uranus: The Tilted Planet
Credit: NASA, Voyager 2
This picture was snapped by the Voyager 2 spacecraft in 1986 - the only spacecraft ever to visit Uranus. Uranus is the third largest planet after Jupiter and Saturn. Uranus has many moons and a ring system. Uranus is composed mostly of liquid water, methane and ammonia, surrounded by a thick gas atmosphere of mostly hydrogen and helium. Uranus is peculiar in that its rotation axis is greatly tilted and sometimes points near the sun. It remains an astronomical mystery why Uranus' axis is so tilted. Uranus and Neptune are very similar.
1995 August 17
Neptune: Big Blue Giant
Credit: NASA, Voyager 2, Copyright Calvin J. Hamilton
This picture was taken by the Voyager 2 spacecraft in 1986 - the only spacecraft ever to visit Neptune. Neptune will be the farthest planet from the Sun until 1999, when the elliptical orbit of Pluto will cause it to once again resume this status. Neptune, like Uranus, is composed mostly of liquid water, methane and ammonia, is surrounded by a thick gas atmosphere of mostly hydrogen and helium, and has many moons and rings. Neptune's moon Triton is unlike any other and has active volcanoes. The nature of Triton's unusual orbit around Neptune is the focus of much discussion and speculation.
Neptune: Big Blue Giant
Credit: NASA, Voyager 2, Copyright Calvin J. Hamilton
This picture was taken by the Voyager 2 spacecraft in 1986 - the only spacecraft ever to visit Neptune. Neptune will be the farthest planet from the Sun until 1999, when the elliptical orbit of Pluto will cause it to once again resume this status. Neptune, like Uranus, is composed mostly of liquid water, methane and ammonia, is surrounded by a thick gas atmosphere of mostly hydrogen and helium, and has many moons and rings. Neptune's moon Triton is unlike any other and has active volcanoes. The nature of Triton's unusual orbit around Neptune is the focus of much discussion and speculation.
1995 August 18
Pluto: The Frozen Planet
Credit: NASA, Hubble Space Telescope, R. Albrecht (ESA/ESO)
The Hubble Space Telescope imaged Pluto and its moon Charon in 1994. Pluto is usually the most distant planet from the Sun but because of its elliptic orbit Pluto crossed inside of Neptune's orbit in 1979 and will cross back out again in 1999. Compared to the other planets, very little is known about Pluto. Pluto is smaller than any other planet and even smaller than several other planet's moons. From Pluto, the Sun is just a tiny point of light. Pluto is probably composed of frozen rock and ice, much like Neptune's moon Triton. Pluto has not yet been visited by a spacecraft, but a mission is being planned for the next decade.
Pluto: The Frozen Planet
Credit: NASA, Hubble Space Telescope, R. Albrecht (ESA/ESO)
The Hubble Space Telescope imaged Pluto and its moon Charon in 1994. Pluto is usually the most distant planet from the Sun but because of its elliptic orbit Pluto crossed inside of Neptune's orbit in 1979 and will cross back out again in 1999. Compared to the other planets, very little is known about Pluto. Pluto is smaller than any other planet and even smaller than several other planet's moons. From Pluto, the Sun is just a tiny point of light. Pluto is probably composed of frozen rock and ice, much like Neptune's moon Triton. Pluto has not yet been visited by a spacecraft, but a mission is being planned for the next decade.
1995 August 19
Our Solar System from Voyager
Credit: NASA, Voyager 1,
After taking its spectacular pictures of the outer solar system planets, Voyager 1 looked back at six planets from the inner solar system. Here Venus, Earth, Jupiter, Saturn, Uranus, and Neptune, were all visible across the sky. Each, however, was now just a small speck of light, dimmer than many of the stars in the sky. Voyager 1 is only one of four human-made objects to leave our Solar System, the other three being Voyager 2, and Pioneer 10 and 11.
Our Solar System from Voyager
Credit: NASA, Voyager 1,
After taking its spectacular pictures of the outer solar system planets, Voyager 1 looked back at six planets from the inner solar system. Here Venus, Earth, Jupiter, Saturn, Uranus, and Neptune, were all visible across the sky. Each, however, was now just a small speck of light, dimmer than many of the stars in the sky. Voyager 1 is only one of four human-made objects to leave our Solar System, the other three being Voyager 2, and Pioneer 10 and 11.
1995 August 20
Announcing Comet Hale-Bopp
Credit: Erich Meyer and Herbert Raab, Austria
The pictured fuzzy patch may become one of the most spectacular comets this century. Although it is very hard to predict how bright a comet will become, Comet Hale-Bopp, named for its discoverers, was spotted farther from the Sun than any previous comet - a good sign that it could become very bright, easily visible to the naked eye. This picture was taken on July 25th 1995, only two days after its discovery. A comet bright enough to see without a telescope occurs only about once a decade. The large coma and long tail of bright comets are so unusual and impressive that they have been considered omens of change by many cultures. A comet does not streak by in few seconds - but it may change its position and structure noticeably from night to night.
Announcing Comet Hale-Bopp
Credit: Erich Meyer and Herbert Raab, Austria
The pictured fuzzy patch may become one of the most spectacular comets this century. Although it is very hard to predict how bright a comet will become, Comet Hale-Bopp, named for its discoverers, was spotted farther from the Sun than any previous comet - a good sign that it could become very bright, easily visible to the naked eye. This picture was taken on July 25th 1995, only two days after its discovery. A comet bright enough to see without a telescope occurs only about once a decade. The large coma and long tail of bright comets are so unusual and impressive that they have been considered omens of change by many cultures. A comet does not streak by in few seconds - but it may change its position and structure noticeably from night to night.
1995 August 21
An Orbiting Iceberg
Credit: European Space Agency, Giotto Camera Team.
A comet nucleus, formed from the primordial stuff of the solar system, resembles a very dirty iceberg. Orbiting far from our Sun, it can remain frozen, preserved for billions of years. Occasionally, a chance gravitational encounter will alter this distant orbit and send the nucleus plummeting towards the inner solar system. In 1986, the European spacecraft Giotto visited the nucleus of Halley's comet as it approached the sun. Data from Giotto's cameras were used to produce this enhanced image which shows surface features on the dark nucleus against the bright background of clouds of gasses produced as the icy material was vaporized by the Sun's heat. The potato shaped nucleus measures about 10 miles across.
An Orbiting Iceberg
Credit: European Space Agency, Giotto Camera Team.
A comet nucleus, formed from the primordial stuff of the solar system, resembles a very dirty iceberg. Orbiting far from our Sun, it can remain frozen, preserved for billions of years. Occasionally, a chance gravitational encounter will alter this distant orbit and send the nucleus plummeting towards the inner solar system. In 1986, the European spacecraft Giotto visited the nucleus of Halley's comet as it approached the sun. Data from Giotto's cameras were used to produce this enhanced image which shows surface features on the dark nucleus against the bright background of clouds of gasses produced as the icy material was vaporized by the Sun's heat. The potato shaped nucleus measures about 10 miles across.