Solar System of Sol
Our solar system consists of an average star we call the Sun (Sol), the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.
It includes: the satellites of the planets; numerous comets, asteroids, and meteoroids; and the interplanetary medium.
The Sun is the richest source of electromagnetic energy (mostly in the form of heat and light) in the solar system. The Sun’s nearest known stellar neighbor is a red dwarf star called Proxima Centauri, at a distance of 4.3 light years away.
The whole solar system, together with the local stars visible on a clear night, orbits the center of our home galaxy, a spiral disk of 200 billion stars we call the Milky Way.
The Milky Way has two small galaxies orbiting it nearby, which are visible from the southern hemisphere. They are called the Large Magellanic Cloud and the Small Magellanic Cloud.
The nearest large galaxy is the Andromeda Galaxy. It is a spiral galaxy like the Milky Way but is 4 times as massive and is 2 million light years away. Our galaxy, one of billions of galaxies known, is traveling through intergalactic space.
The planets, most of the satellites of the planets and the asteroids revolve around the Sun in the same direction, in nearly circular orbits. When looking down from above the Sun’s north pole, the planets orbit in a counter-clockwise direction. The planets orbit the Sun in or near the same plane, called the ecliptic.
Pluto is a special case in that its orbit is the most highly inclined (18 degrees) and the most highly elciptical of all the planets. Because of this, for part of its orbit, Pluto is closer to the Sun than is Neptune.
The axis of rotation for most of the planets is nearly perpendicular to the ecliptic. The exceptions are Uranus and Pluto, which are tipped on their sides.
This meteorite was collected from the Allan Hills in Antarctica. Meteorites are bits of rock that are captured by a planet’s gravity and pulled to the surface. This meteorite is of a type named chondrite and is thought to have formed at the same time as the planets in the solar nebula, about 4.55 billion years ago.
Discovered at Reckling Peak, Antarctica, this type of meteorite is known as an achondrite. It has a 
This iron meteorite was found at Derrick Peak, Antarctica. This type of meteorite gets its name because it is mostly made of the elements iron and nickel. This sample is probably a small piece from the core of a large asteroid that broke apart.
Even though this meteorite was collected in Elephant Moraine, Antarctica in 1979, some scientists believe that it came from the planet Mars. The minerals found in this rock are similar to those that scientists expect to find in rocks on Mars. This meteorite also contains vesicles, or shiny pockets, which contain air very much like the air measured on Mars by the Viking spacecraft. This meteorite is 180 million years old.
This meteorite, called EETA 79001, was found on the ice in Antarctica, and is quite likely from Mars. For scale, the cube at the lower right is 1 centimeter on a side. The meteorite is partly covered by a black glassy layer, the fusion crust. The fusion crust forms when the meteorite enters the Earth’s atmosphere at high speed. Friction heating melts the outer portion of the meteorite. Inside, the meteorite is gray. It is a 
Rocks are often made of small mineral grains that can’t be seen clearly without a microscope. To see these small grains, scientists grind and polish rock samples very thin so light can pass through them. This microscopic view, 2.3 millimeters across, is in false color, produced by holding polarizing filters above and below the microscopic slide. These filters cause different minerals to have distinctive colors, allowing easy identification of the minerals. Most of this meteorite (in yellow, green, pink, and black) is the mineral olivine, which is common in some basaltic rocks. The striped grain near the center is the mineral pyroxene.
This meteorite is assumed to be a sample of the crust of the asteroid 
As comets approach the Sun they develop enormous tails of luminous material that extend for millions of kilometers from the head, away from the Sun. When far from the Sun, the nucleus is very cold and its material is frozen solid within the nucleus. In this state comets are sometimes referred to as a "dirty iceberg" or "dirty snowball," since over half of their material is ice. When a comet approaches within a few 
Each time a comet visits the Sun, it loses some of its volatiles. Eventually, it becomes just another rocky mass in the solar system. For this reason, comets are said to be short-lived, on a cosmological time scale. Many scientists believe that some 
This color photograph of the Comet Kohoutek was taken by members of the lunar and planetary laboratory photographic team from the University of Arizona. They photographed the comet from the Catalina observatory with a 35mm camera on January 11, 1974.
This is a CCD image of Comet 1993a Mueller, taken on October 6, 1993 with a 288mm f/5.2 Schmidt-Cassegrain telescope. The comet has a coma diameter of 91 centimeters and a fan-shaped tail, up to 2.13 meters long.
This photograph was taken by amateur astronomer John Laborde on March 9, 1976. This picture shows two distinct tails. The thin blue 
These NASA Hubble Space Telescope pictures of Comet Hale-Bopp show a remarkable "pinwheel" pattern and a blob of free-flying debris near the nucleus. The bright clump of light along the spiral (above the nucleus, which is near the center of the frame) may be a piece of the comet’s icy crust that was ejected into space by a combination of ice evaporation and the comet’s rotation, and which then disintegrated into a bright cloud of particles.
Asteroids are rocky and metallic objects that orbit the Sun but are too small to be considered planets. They are known as minor planets. Asteroids range in size from Ceres, which has a diameter of about 1,000 kilometers, down to the size of pebbles. Sixteen asteroids have a diameter of 240 kilometers or greater. They have been found inside Earth’s orbit to beyond Saturn’s orbit. Most, however, are contained within a main belt that exists between the orbits of Mars and Jupiter. Some have orbits that cross Earth’s path and some have even hit the Earth in times past. One of the best preserved examples is 
Asteroids are material left over from the formation of the solar system. One theory suggests that they are the remains of a planet that was destroyed in a massive collision long ago. More likely, asteroids are material that never coalesced into a planet. In fact, if the estimated total mass of all asteroids was gathered into a single object, the object would be less than 1,500 kilometers across — less than half the diameter of our Moon.
Pluto was discovered by Clyde W. Tombaugh on February 18, 1930, making it the last planet found in our Solar System. Pluto is usually farther from the Sun then any of the nine planets; however, due to the 
This view of Pluto was taken by the Hubble Space Telescope. It shows a rare image of tiny Pluto with its moon Charon, which is slightly smaller than the planet. Because Pluto has not yet been visited by any spacecraft, it remains a mysterious planet. Due to its great distance from the sun, Pluto’s surface is believed to reach temperatures as low as -240°C. From Pluto’s surface, the Sun appears as only a very bright star.
This is the clearest view yet of the distant planet Pluto and its moon, Charon, as revealed by the Hubble Space Telescope (HST). The image was taken on February 21, 1994, when the planet was 4.4 billion kilometers from the Earth. The HST corrected optics show the two objects as clearly separate and sharp disks. This now allows astronomers to measure directly (to within about 1 percent) Pluto’s diameter of 2,320 kilometers and Charon’s diameter of 1,270 kilometers. The HST observations show that Charon is bluer than Pluto. This means that the worlds have different surface composition and structure. A bright highlight on Pluto indicates that it might have a smoothly reflecting surface layer. A detailed analysis of the HST image also suggests that there is a bright area parallel to the equator of Pluto. However, subsequent observations are needed to confirm that this feature is real. The new HST image was taken when Charon was near its maximum elongation from Pluto (0.9 arcseconds). The two worlds are 19,640 kilometers apart.
The never-before-seen surface of the distant planet Pluto is resolved in these NASA Hubble Space Telescope pictures. These images, which were made in blue light, show that Pluto is an unusually complex object, with more large-scale contrast than any planet except Earth. Pluto probably shows even more contrast and perhaps sharper boundaries between light and dark areas than is shown here, but Hubble’s resolution (just like early telescopic views of Mars) tends to blur edges and blend together small features sitting inside larger ones. The two smaller inset pictures at the top are actual images from Hubble. North is up. Each square pixel (picture element) is more than 160 kilometers across. At this resolution, Hubble discerns roughly 12 major "regions" where the surface is either bright or dark. The larger images (bottom) are from a global map constructed through computer image processing performed on the Hubble data. Opposite hemispheres of Pluto are seen in these two views.
This is the first image-based surface map of the solar system’s most remote planet, Pluto. The map, which covers 85 percent of the planet’s surface, confirms that Pluto has a dark equatorial belt and bright polar caps, as inferred from ground-based light curves obtained during the mutual eclipses that occurred between Pluto and its satellite Charon in the late 1980s. The brightness variations in this map may be due to topographic features such as basins and fresh impact craters. However, most of the surface features are likely produced by the complex distribution of frosts that migrate across Pluto’s surface with its orbital and seasonal cycles and chemical byproducts deposited out of Pluto’s nitrogen-methane atmosphere. Names may later be proposed for some of the larger regions. Image reconstruction techniques smooth out the coarse pixels in the four raw images to reveal major regions where the surface is either bright or dark. The black strip across the bottom corresponds to the region surrounding Pluto’s south pole, which was pointed away from Earth when the observations were made, and could not be imaged.
This image of Pluto was taken with the 2.6 meter Nordic Optical Telescope, located at La Palma, Canary Islands. It is a good example of the best imagery that can be obtained from Earth-based telescopes.
This is a painting by Pat Rawlings of the Pluto Express mission scheduled for launch in 2001 to arrive at Pluto around 2013. The mission will consist of a pair of small, fast, relatively cheap spacecraft weighing less than 100 kilograms each. The spacecraft will pass within 15,000 kilometers of Pluto and Charon.
Neptune is the outermost planet of the gas giants. It has an equatorial diameter of 49,500 kilometers. If Neptune were hollow, it could contain nearly 60 Earths. Neptune orbits the Sun every 165 years. It has eight moons, six of which were found by Voyager. A day on Neptune is 16 hours and 6.7 minutes. 
This picture of Neptune was taken by Voyager 2 on August 20, 1989. One of the great cloud Features, dubbed the Great Dark Spot by Voyager scientists, can be seen toward the center of the image. It is at a latitude of 22 degrees south and circuits Neptune every 18.3 hours. The bright clouds to the south and east of the Great Dark Spot constantly change their appearances in periods as short as four hours.
These almost true-color pictures of Neptune were constructed from HST/WFPC2 images taken in blue (467-nm), green (588-nm), and red (673-nm) spectral filters. There is a bright cloud feature at the south pole, near the bottom right of the image. Bright cloud bands can be seen at 30S and 60S latitude. The northern hemisphere also includes a bright cloud band centered near 30° N latitude. The second picture was compiled from images taken after the planet had rotated about 180 degrees of longitude (about 9 hours later) to show the opposite hemisphere. One feature that is conspicuous by its absence is the storm system known as the 
These three images were taken on October 10, October 18 and November 2, 1994, when Neptune was 4.5 billion kilometers from Earth. Building on Voyager’s initial discoveries, Hubble has revealed that Neptune has a remarkably dynamic atmosphere that changes over just a few days. The temperature difference between Neptune’s strong internal heat source and its frigid cloud tops (-162° Celsius) might trigger instabilities in the atmosphere that drive these large-scale weather changes. The pink features are high-altitude methane ice crystal clouds. 
In June 1994, the Hubble telescope revealed that the 
This image shows bands of sunlit cirrus-like clouds in Neptune’s northern hemisphere. These clouds cast shadows on the blue cloud deck 56 kilometers below. The white streaky clouds are from 48 to 160 kilometers wide and extend for thousands of kilometers. 
This Voyager 2 image has been processed by computers so that both the clouds’ structure in the dark regions near the pole and the bright clouds east of the Great Dark Spot are visible. Small trails of clouds trending east to west and large-scale structure east of the Great Dark Spot all suggest that waves are present in the atmosphere and play a large role in the type of clouds that are visible.
Feathery white clouds fill the boundary between the dark and light blue regions on the Great Dark Spot. The pinwheel shape of both the dark boundary and the white cirrus suggests that the storm system rotates counterclockwise. Periodic small scale patterns in the white cloud, possibly waves, are short lived and do not persist from one Neptunian rotation to the next. 
This Voyager 2 image shows a beautiful dual-crescent view of Neptune and Triton. The image, acquired on August 31, 1989, is a parting tribute of the Voyager mission.
This image shows the Small Dark Spot, which is south of the Great Dark Spot. The small spot is thought to be a storm in Neptune’s atmosphere, perhaps similar to Jupiter’s Great Red Spot. 
These two 591-second exposures of the rings of Neptune were taken by Voyager 2 on August 26, 1989 from a distance of 280,000 kilometers. The two main rings are clearly visible and appear complete over the region imaged. Also visible in this image is the inner faint ring at about 42,000 kilometers from the center of Neptune, and the faint band which extends smoothly from the 53,000 kilometer ring to roughly halfway between the two bright rings. The bright glare in the center is due to over-exposure of the crescent of Neptune. Numerous bright stars are evident in the background. Both rings are continuous. 
This portion of one of Neptune’s rings appears to be twisted. Scientists believe it looks this way because the original material in the rings was in clumps that formed streaks as the material orbited Neptune. The motion of the spacecraft added to the twisted appearance by causing a slight smearing in the image. 
This view of Uranus was acquired by 
This view of Uranus was acquired by NASA’s Hubble Space Telescope and reveals a pair of bright clouds in the planet’s southern hemisphere, and a high altitude haze that forms a "cap" above the planet’s south pole. This is just one view of a sequence of three that can be obtained by selecting the above gif image. Hubble’s new view was obtained on August 14, 1994, when Uranus was 2.8 billion kilometers from Earth. These atmospheric details were only previously seen by the Voyager 2 spacecraft, which flew by Uranus in 1986. Since then, detailed observations of Uranus’s atmospheric features have not been possible because the planet is at the resolution limit of ground-based telescopes. Hubble’s Wide Field Planetary Camera 2 observed Uranus through a filter that is sensitive to light reflected by a pair of high altitude clouds. This makes a high altitude haze over Uranus’ south polar region clearly visible, along with a pair of high altitude clouds or plume-type features that are 4,300 and 3,100 kilometers across, respectively. Two additional Hubble Telescope images can be found here.
The discovery of two 
The 9 known rings of Uranus are visible here. The somewhat fainter, pastel lines seen between the rings are artifacts of computer enhancement. Six narrow-angle images were used to extract color information from the extremely dark and faint rings. The final image was made from three color averages and represents an enhanced, false-color view. The image shows that the brightest, or epsilon, ring at top is neutral in color, with the fainter 8 remaining rings showing color differences between them.
This montage of images of the Uranian system was prepared from an assemblage of images taken by the Voyager 2 spacecraft during its Uranus encounter in January 1986. This artist’s view shows 
Saturn is the sixth planet from the Sun and is the second largest in the solar system with an equatorial diameter of 119,300 kilometers. Much of what is known about the planet is due to the Voyager explorations in 1980-81. 
NASA’s Voyager 2 took this photograph of Saturn on July 21, 1981, when the spacecraft was 33.9 million kilometers from the planet. Two bright, presumably 
In one of nature’s most dramatic examples of "now-you see-them, now-you-don’t," NASA’s Hubble Space Telescope captured Saturn on May 22, 1995, as the planet’s magnificent ring system turned edge-on. This ring-plane crossing occurs approximately every 15 years when the Earth passes through Saturn’s ring plane. The rings do not disappear completely because the edge of the rings reflects sunlight. The dark band across the middle of Saturn is the shadow of the rings cast on the planet (the Sun is almost 3 degrees above the ring plane.) The bright stripe directly above the ring shadow is caused by sunlight reflected off the rings onto Saturn’s atmosphere. Two of Saturn’s icy moons are visible as tiny starlike objects in or near the ring plane.
This image, taken by the Hubble Space Telescope, shows a rare storm that appears as a white arrowhead-shaped feature near the planet’s equator. The storm is generated by an upwelling of warmer air, similar to a terrestrial thunderhead. The east-west extent of this storm is equal to the diameter of the Earth (12,700 kilometers). The Hubble images are sharp enough to reveal that Saturn’s prevailing winds shape a dark "wedge" that eats into the western (left) side of the bright central cloud. The planet’s strongest eastward winds, clocked at 1,600 kilometers per hour based on Voyager spacecraft images taken in 1980-81, are at the latitude of the wedge. To the north of this arrowhead-shaped feature, the winds decrease so that the storm center is moving eastward relative to the local flow. The clouds expanding north of the storm are swept westward by the winds at higher latitudes. The strong winds near the latitude of the dark wedge blow over the northern part of the storm, creating a secondary disturbance that generates the faint white clouds to the east (right) of the storm center. The storm’s white clouds are ammonia ice crystals that form when an upward flow of warmer gases shoves its way through Saturn’s frigid cloud tops.
The top image shows the first image ever taken of bright auroras at Saturn’s northern and southern poles, as seen in far ultraviolet light by the Hubble Space Telescope. Hubble resolves a luminous, circular band centered on the north pole, where an enormous auroral curtain rises as far as 2,000 kilometers above the cloud tops. This curtain changed rapidly in brightness and extent over the two hour period of HST observations. The aurora is produced as trapped charged particles precipitating from the magnetosphere collide with atmospheric gases. As a result of the bombardment, Saturn’s gases glow at far-ultraviolet wavelengths (110-160 nanometers). These wavelengths are absorbed by the Earth’s atmosphere, and can only be observed from space-based telescopes. For comparison, the bottom image is a visible-light color composite of Saturn as seen by Hubble on December 1, 1994. Unlike the ultraviolet image, Saturn’s familiar atmospheric belts and zones are clearly seen. The lower cloud deck is not visible at UV wavelengths because sunlight is reflected from higher in the atmosphere.
Two days after its encounter with Saturn, Voyager 1 looked back on the planet from a distance of more than 5 million kilometers. This view of Saturn has never been seen by an earth based telescope, since the earth is so close to the Sun only the sunlit face of Saturn can be seen.
This color-enhanced image shows the dark spoke-like features in the rings. The spokes seem to form very rapidly with sharp edges and then dissipate. The A ring appears as the outermost bands but in this image appears as two bands divided by the Encke’s division. The Cassini’s division divides the A and B bands.
Possible variations in chemical composition from one part of Saturn’s ring system to another are visible in this Voyager 2 picture as subtle color variations that can be recorded with special computer-processing techniques. This highly enhanced color view was assembled from clear, orange and ultraviolet frames obtained August 17, 1981 from a distance of 8.9 million kilometers. In addition to the previously known blue color of the C-ring and the Cassini Division, the picture shows additional color differences between the inner B-ring and outer region (where the spokes form) and between these and the A-ring.
Saturn’s outermost ring, the F-ring, is a complex structure made up of two narrow, braided, bright rings along which "knots" are visible. Scientists speculate that the knots may be clumps of ring material, or mini moons. The F-ring was photographed at a range of 750,000 kilometers.
This montage of images of the Saturnian system was prepared from an assemblage of images taken by the Voyager 1 spacecraft during its Saturn encounter in November 1980. This artist’s view shows Dione in the forefront, Saturn rising behind, Tethys and Mimas fading in the distance to the right, Enceladus and Rhea off Saturn’s rings to the left, and Titan in its distant orbit at the top.
This image shows Saturn’s satellites approximately to scale as well as Saturn’s ring structure.