- Nov 4, 2013
These are some suggestionsJupiter -
about planets to be added
about planets to be added
If the sun were as tall as a typical front door, the Earth would be the size of a nickel and Jupiter would be about as big as a basketball. Jupiter orbits our sun, a star. Jupiter is the fifth planet from the sun at a distance of about 778 million km (484 million miles) or 5.2 AU. One day on Jupiter takes about 10 hours (the time it takes for Jupiter to rotate or spin once). Jupiter makes a complete orbit around the sun (a year in Jovian time) in about 12 Earth years (4,333 Earth days). Jupiter is a gas-giant planet and therefore does not have a solid surface. However, it is predicted that Jupiter has an inner, solid core about the size of the Earth. Jupiter's atmosphere is made up mostly of hydrogen (H2) and helium (He). Jupiter has 50 known moons, with an additional 17 moons awaiting confirmation of their discovery -- that is a total of 67 moons. Jupiter has a faint ring system that was discovered in 1979 by the Voyager 2 mission. Many missions have visited Jupiter and its system of moons. The Juno mission will arrive at Jupiter in 2016. Jupiter cannot support life as we know it. However, some of Jupiter's moons have oceans underneath their crusts that might support life. Jupiter's Great Red Spot is a gigantic storm (about the size of two to three Earths) that has been raging for hundreds of years.
Looking like a giant pizza covered with melted cheese and splotches of tomato and ripe olives, Io is the most volcanically active body in the solar system. Volcanic plumes rise 300 km (or 190 miles) above the surface, with material spewing out at nearly half the required escape velocity. Io is a bit larger than Earth's Moon, third for Jupiter, and fifth in distance from the planet. There is lots of generated heat within Io from the tidal pumping, keeping much of its subsurface crust in liquid form seeking any available escape route to the surface to relieve the pressure. Thus, the surface of Io is constantly renewing itself, filling in any impact craters with molten lava lakes and spreading smooth new floodplains of liquid rock. The composition of this material is not yet entirely clear, but theories suggest that it is largely molten sulfur and its compounds (which would account for the variegated coloring) or silicate rock (which would better account for the apparent temperatures, which may be too hot to be sulfur). Sulfur dioxide is the primary constituent of a thin atmosphere on Io. It has no water to speak of, unlike the other, colder Galilean moons. Data from the Galileo spacecraft indicates that an iron core may form Io's center, thus giving Io its own magnetic field. Io's orbit is a cozy, more or less, 422,000 km (262,000 miles) from Jupiter, cuts across the planet's powerful magnetic lines of force, thus turning Io into a electric generator. Io can develop 400,000 volts across itself and create an electric current of 3 million amperes. This current takes the path of least resistance along Jupiter's magnetic field lines to the planet's surface, creating lightning in Jupiter's upper atmosphere.
Jupiter's icy moon Europa is slightly smaller than the Earth's Moon. Like the Earth, Europa is thought to have an iron core, a rocky mantle and a surface ocean of salty water. Unlike on Earth, however, this ocean is deep enough to cover the whole surface of Europa, and being far from the sun, the ocean surface is globally frozen over. Europa orbits Jupiter every 3.5 days and is phase locked -- just like Earth's Moon -- so that the same side of Europa faces Jupiter at all times. However, because Europa's orbit is eccentric (i.e. an oval or ellipse not a circle) when it is close to Jupiter the tide is much higher than when it is far from Jupiter. Thus tidal forces raise and lower the sea beneath the ice, causing constant motion and likely causing the cracks we see in images of Europa's surface from visiting robotic probes. This "tidal heating" causes Europa to be warmer than it would otherwise be at its average distance of about 780,000,000 km (485,000,000 miles) from the sun, more than five times as far as the distance from the Earth to the sun. The warmth of Europa's liquid ocean could prove critical to the survival of simple organisms within the ocean, if they exist.
Ganymede is the largest satellite in our solar system. It is larger than Mercury and Pluto, and three-quarters the size of Mars. If Ganymede orbited the sun instead of orbiting Jupiter, it would easily be classified as a planet. Ganymede has three main layers. A sphere of metallic iron at the center (the core, which generates a magnetic field), a spherical shell of rock (mantle) surrounding the core, and a spherical shell of mostly ice surrounding the rock shell and the core. The ice shell on the outside is very thick, maybe 800 km (497 miles) thick. The surface is the very top of the ice shell. Though it is mostly ice, the ice shell might contain some rock mixed in. Scientists believe there must be a fair amount of rock in the ice near the surface. Ganymede's magnetic field is embedded inside Jupiter's massive magnetosphere. Astronomers using the Hubble Space Telescope found evidence of thin oxygen atmosphere on Ganymede in 1996. The atmosphere is far too thin to support life as we know it. In 2004, scientists discovered irregular lumps beneath the icy surface of Ganymede. The irregular masses may be rock formations, supported by Ganymede's icy shell for billions of years. This tells scientists that the ice is probably strong enough, at least near the surface, to support these possible rock masses from sinking to the bottom of the ice. However, this anomaly could also be caused by piles of rock at the bottom of the ice. Spacecraft images of Ganymede show the moon has a complex geological history. Ganymede's surface is a mixture of two types of terrain. Forty percent of the surface of Ganymede is covered by highly cratered dark regions, and the remaining sixty percent is covered by a light grooved terrain, which forms intricate patterns across Ganymede. The term "sulcus," meaning a groove or burrow, is often used to describe the grooved features. This grooved terrain is probably formed by tensional faulting or the release of water from beneath the surface. Groove ridges as high as 700 m (2,000 feet) have been observed and the grooves run for thousands of kilometers across Ganymede's surface. The grooves have relatively few craters and probably developed at the expense of the darker crust. The dark regions on Ganymede are old and rough, and the dark cratered terrain is believed to be the original crust of the satellite. Lighter regions are young and smooth (unlike Earth's Moon). The largest area on Ganymede is called Galileo Regio. The large craters on Ganymede have almost no vertical relief and are quite flat. They lack central depressions common to craters often seen on the rocky surface of the Moon. This is probably due to slow and gradual adjustment to the soft icy surface. These large phantom craters are called palimpsests, a term originally applied to reused ancient writing materials on which older writing was still visible underneath newer writing. Palimpsests range from 50 to 400 km in diameter. Both bright and dark rays of ejecta exist around Ganymede's craters -- rays tend to be bright from craters in the grooved terrain and dark from the dark cratered terrain.
With a diameter of over 4,800 km (2,985 miles), Callisto is the third largest satellite in the solar system and is almost the size of Mercury. Callisto is the outermost of the Galilean satellites, and orbits beyond Jupiter's main radiation belts. It has the lowest density of the Galilean satellites (1.86 grams/cubic cm). Its interior is probably similar to Ganymede except the inner rocky core is smaller, and this core is surrounded by a large icy mantle. Callisto's surface is the darkest of the Galileans, but it is twice as bright as our own Moon. Callisto is the most heavily cratered object in the solar system. It is thought to be a long dead world, with hardly any geologic activity on its surface. In fact, Callisto is the only body greater than 1000 km in diameter in the solar system that has shown no signs of undergoing any extensive resurfacing since impacts have molded its surface. With a surface age of about 4 billion years, Callisto has the oldest landscape in the solar system.
Other Suggestions By Me:
Populating, Items, Planets, and More