Our Family of Planets and Moons - The Solar System Image Gallery
written by: Rod Martin, Jr.•edited by: RC Davison•updated: 9/28/2011
To the ancients, planets were merely wandering points of light against a backdrop of fixed stars. The only moon they knew was that of our own Earth. With modern technology, we have seen each of these wanderers up close in all their grandeur and beauty.
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Father Sun - Parent to the Solar System
Our Sun is a gigantic ball of hot gas, more massive than all of the mountains of Earth. In fact, eminently more massive than our entire planet. Just as Jupiter could easily swallow the Earth, Sol (our sun) could swallow Jupiter and every other planet in the Solar System. The image was taken in the extreme ultraviolet band of light.
Distance: 93 million miles (8.3 light minutes).
Mass: 330,000 times that of Earth.
Diameter: 865,000 miles (109 times that of Earth).
This is Venus with the veil stripped away. A false-color view produced by x-ray imaging, digging below the thick cloud layer to the tortured surface underneath.
Though Mercury is far closer to the Sun, Venus is far hotter because of its thick, "greenhouse" atmosphere—a pressure 92 times that at sea level on Earth. The surface temperature is close to 860 °F. Because of tidal braking by the Sun, Venus has an extremely slow rotation. Despite this, the temperature on Venus is roughly the same both day and night.
Our home planet, Earth, as seen from space. From the Sahara Desert to Australia and from the North Pole to the Southern Indian Ocean, this cloud-speckled view of our home remains one of the most lovely views of our planet. Australia, the Philippines and Japan are in early evening, while the Middle East sweats under the mid-day Sun. Notice the detail of the Mediterranean and the turquoise shallows of the Caspian Sea.
Our Moon is Earth's closest neighbor in space. Six different missions have landed men on its surface. It remains the fifth largest satellite in the Solar System. An airless world, it stands tidally locked so that only one face is ever presented to the Earth. Only after the beginning of the space age did humanity ever gaze on the lunar far side.
Thin, carbon dioxide clouds dot the surface of Mars from Olympus Mons on the left, across the Tharsis Highlands. A short distance from veiled Olympus Mons (the tallest volcano in the Solar System) stand the three large calderas of Tharsis Montes ranging from the Northeast to Southwest across the western highlands. The southernmost is Arsia Mons, the central peak is Pavonis Mons, and the northernmost is Ascraeus Mons. None of these three stand as high as Olympus Mons, despite the greater starting elevation of the highlands.
Just below the middle, in the center of this image, starts the Valles Marineris—a deep gash in the planet's surface which runs eastward from here, one-fourth of the way around Mars.
The atmosphere is extremely thin, roughly equivalent to that on Earth at an altitude 21 miles above sea level. No surface water exists, but there is evidence that the surface has been eroded by liquid water in the remote past. And so far, no indigenous life has been found on Mars.
Ceres is not only the largest asteroid—that field of rocky material between Mars and Jupiter—but it is also the only dwarf planet in the inner Solar System. The remainder of the asteroids are too small to form spherical shapes under their own gravitational pull.
With all of the high quality photos we've received from the Hubble Space Telescope, the graininess of this picture merely shows how difficult the asteroids are as imaging targets.
Jupiter is the king of planets in our Solar System. The colorful bands and swirls in this picture are exaggerated to show off the detail. The Great Red Spot near the planet's equator could hold two or three planets the size of Earth.
From the Sun, this is the first of the gas giant planets, along with Saturn, Uranus and Neptune.
Jupiter has dozens of moons, with four large satellites known as the Galilean moons, after their discoverer, Galileo Galilei.
Io is the innermost of the Galilean moons of Jupiter—one of the four Medician stars, as Galileo called them. Io (pronounced EYE-oh), is the most volcanically active body in the Solar System. This is because of the tidal stretching caused by Jupiter and nearby Europa. The coloration is caused in part by the moon's high concentration of sulfur. In fact, Io leaves a trail of sulfur in its orbit around Jupiter from all of the eruptions.
Apoapsis (farthest from the planet): 263,000 miles.
Slightly smaller than Earth's moon, Europa has a very tenuous atmosphere of oxygen. This moon has one of the smoothest solid surfaces in the Solar System, made mostly of water ice. The striations crisscrossing the surface are cracks in the ice, but surprisingly there are very few meteor craters. There has been some speculation that a liquid water ocean exists underneath the surface allowing the possibility of some form of life. The heat for this liquid water is from the tidal flexing from Jupiter and its sibling moons, similar to the flexing which drives the volcanism on Io. The image on the right is enhanced to bring out more of the detail.
Apoapsis (farthest from the planet): 421,000 miles.
Jupiter's Ganymede - Largest Moon in the Solar System
Ganymede is roughly equal parts silicate rock and water ice and it possesses an extremely thin oxygen atmosphere. It is also the only moon in the Solar System with its own magnetosphere. Ganymede is the largest moon in the Solar System and 77% the diameter of Mars.
Apoapsis (farthest from the planet): 666,000 miles.
Callisto is the third-largest moon in the Solar System, after Ganymede and Titan. It is also 99% the diameter of Mercury, but contains only about a third of that planet's mass. Unlike the other three Galilean moons, Callisto does not suffer the tidal heating experienced by its siblings. It has an extremely thin atmosphere of carbon dioxide and possibly oxygen.
Apoapsis (farthest from the planet): 1,179,000 miles.
Periapsis (closest to the planet): 1,162,000 miles.
Saturn is not the only planet in the Solar System with rings, but its complex ring system puts the others to shame by its sheer beauty. The body of the planet is the least dense of any world in the Solar System. If a bath of water large enough could be found, Saturn would float in it because of its low density. Saturn is the second-largest planet in our star system. It possesses dozens of moons, most of them only very large rocks—likely captured asteroids. Saturn's largest moon, Titan, is the second-largest moon in the Solar System.
Saturn is also the most "flattened" planet in the Solar System—with a difference between polar and equatorial diameters of about 10%.
This amazing view is from beyond Saturn, looking back toward our Sun. Nearly every particle near Saturn has been lit up, revealing a far larger array of debris in the plane of the ring system.
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Saturn's Titan with Tethys
Titan is Saturn's largest moon and second-largest moon in the Solar System. It is the only moon with a substantial atmosphere—mostly nitrogen (98.4%) with varying amounts of methane and other hydrocarbons. The atmosphere is so thick in fact, that surface pressure is about 1.45 times that at sea level on Earth. The surface temperature is close to a frigid −290 °F.
Apoapsis (farthest from the planet): 781,000 miles.
Periapsis (closest to the planet): 738,000 miles.
Orbital Period: 15.945 days.
Mass: 0.0225 times that of Earth.
Diameter: 0.404 times that of Earth.
Tethys is a medium-sized moon of Saturn. It has a very low density, indicating that it consists largely of water ice and very little rocky material.
Uranus is the coldest of the Solar System planets, despite being closer to the Sun than Neptune. Uranus is the third-largest planet in radius, but fourth in mass. It is one of the system's four gas giants.
Blessed with 27 known moons, Uranus has 5 main satellites, namely Miranda, Ariel, Umbriel, Titania and Oberon.
Neptune is the last full-fledged planet in the Solar System. The planet has 13 known moons, but only one with enough mass to become spheroidal under its own gravity. This largest moon is Triton, with a diameter about 0.2122 times that of Earth.
Once upon a time, Pluto was the ninth planet of the Solar System. In recent years, however, Pluto has been demoted to a new category called "dwarf planet." It's large moon, Charon is a significant percentage of the size of Pluto, making the two the closest thing in the Solar System to "twin planets." Well, perhaps "twin dwarf planets." The newly discovered moons of Nix and Hydra reside to the right of the main pair.
A fourth moon of Pluto was discovered by Mark Showalter of the SETI Institute, and announced on July 20, 2011. It has been provisionally named S/2011 P 1 or P4.