Uranus+&+Neptune+-+TD

Getting Started

 * **Click on the edit button above to put your own content on this page.f**

Rubric: [[file:Space Exploration Adventure Rubric.doc]], [[file:Space Exploration Adventure Rubric.pdf]]
** Written Information **: As you enter text, the area will expand. Make sure to check the required details of the assignment and review the rubric (see document links) to self-assess your work. Your paragraphs will be in block format, enter one return between paragraphs. The tab key, indent feature will not appear when typing directly into the wiki page.

Visuals
 * [[image:http://i.space.com/images/i/12553/original/uranus-rings-sideways-multiple-impacts.jpg?1318012036 width="261" height="286" caption="CREDIT: Lawrence Sromovsky, (Univ. Wisconsin-Madison), Keck Observatory"]] || [[image:http://i.space.com/images/i/407/i02/uranus-planet-profile-101111.jpg width="418" height="338" caption="Uranus Infographic"]] ||  ||
 * [[image:http://edu.glogster.com/media/5/31/16/85/31168521.jpg width="300" height="300" caption="http://edu.glogster.com/media/5/31/16/85/31168521.jpg"]] || [[image:http://t1.gstatic.com/images?q=tbn:ANd9GcTv8J54qQpbgdyfwahJl_CfKw1OotWQphIAt9cvfOg9nNDVSSl5ttD0YV7aGQ width="365" height="273" caption="http://t1.gstatic.com/images?q=tbn:ANd9GcTv8J54qQpbgdyfwahJl_CfKw1OotWQphIAt9cvfOg9nNDVSSl5ttD0YV7aGQ"]] ||  ||
 * [[image:http://photojournal.jpl.nasa.gov/images/ppj_hp_pluto.jpg width="297" height="388" caption="Photojournal"]] || [[image:http://solarsystem.nasa.gov/images/Neptune.jpg width="277" height="180" caption="Voyager 2 captured this image of Neptune in 1989." link="http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=2424"]][[image:http://t3.gstatic.com/images?q=tbn:ANd9GcQ5D1bpm7kylWV38SLKf0g6N-TrIpmZdEP5jSnEuybPYG0itYNQKA width="206" height="244" caption="http://t3.gstatic.com/images?q=tbn:ANd9GcQ5D1bpm7kylWV38SLKf0g6N-TrIpmZdEP5jSnEuybPYG0itYNQKA"]] ||  ||

**Works Cited** **Sources** :Iconn.com,Space.com,Nasa.gov, Kids Info Bits

**Sources: Nasa.gov, Space.com, Iconn.org Kids Info Bits**

**Topic: Research Focus** **What is your topic? Similarities Between Uranus and Neptune** **State the focus of your research: What do They have in Common**

**Notes**  Similarities Beetween Uranus and Neptune Uranus and Neptune are the seventh and eighth farthest planets from the sun, respectively. Both are large, massive planets composed mostly of gaseous hydrogen, so they are classified as Jovian (Jupiterlike) planets. Uranus and Neptune are about the same size, and both orbit the sun in roughly circular orbits. Neptune, although slightly smaller, is more massive than Uranus and has a much more active atmosphere. Uranus 's orbital period, the amount of time it takes to revolve once around the sun, is 84 Earth years; for more-distant Neptune, it is 164.8 Earth years. Little was known of these two worlds before the Voyager 2 space probe visited Uranus in 1986 and Neptune in 1989.

Origin and Discovery
Like the other planets in the solar system, Uranus and Neptune formed about 4.5 billion years ago. Observations, computer models, and other evidence suggest how they formed from the cloud of gas and dust known as the solar nebula.

Planetary Formation
Uranus and Neptune were created when icy and rocky materials gathered together among the many solid particles in the colder outer portion of the solar nebula. As they grew more massive, their gravity captured hydrogen and helium gas from the nebula, as well as larger solid bodies called planetesimals orbiting far from the newly formed sun. Because the planetesimals at this distance from the sun were cold enough to remain icy, ice now makes up the majority of the mass of both planets. Uranus and Neptune built up more slowly than did the other Jovian planets, Jupiter and Saturn, because their longer orbital periods meant that they encountered other orbiting bodies less often. When the solar nebula began to break up, Uranus and Neptune had not had time to grow large enough to capture as much gas as Jupiter and Saturn. Therefore, the development of Uranus and Neptune may have stopped before it was complete, and they may represent a middle stage in the development of giant planets. Late in its formation, Uranus may have been struck by a very large proto-planet (planetesimal grown to planet- or planet-size) that was up to two times as massive as Earth. This event would explain the fact that Uranus 's axis of rotation is almost parallel to the plane of its orbit; that is, Uranus appears to be tipped over, with its equator running north and south. Such a collision may also have created the observed thin ring of material around the planet from which most if not all of Uranus 's satellites probably formed. Neptune, which is not tipped over, also has thin rings and numerous satellites, whose origin is probably related in large part to the equatorial ring materials.

Atmospheres
Uranus and Neptune have visible atmospheres composed of about 84 percent hydrogen, 14 percent helium, and 2 percent methane. Neither planet has any solid surface, so locations in their atmospheres are identified by atmospheric pressure. At a pressure of 1 bar, which is equal to air pressure at sea level on Earth, the temperature on Uranus and Neptune is about -325°F (-198°C). Just below this level are thin clouds of condensed methane. Beneath the methane clouds, at pressures of about 3 bars, are thicker decks of clouds that may consist of frozen hydrogen sulfide. Uranus and Neptune also have an unusually high ratio of carbon to hydrogen that may have resulted from the impact of carbon-rich comets during the planets' formation. These comets also contained water and ammonia that would have formed ices in the planets' cold outer atmospheres and sunk to deeper and warmer regions lower in the atmospheres. Because such regions are too deep to have been visible to Voyager 2, the relative amounts of these materials in the planets' atmospheres are not known. However, small amounts of carbon monoxide and nitrogen have been observed in Neptune 's atmosphere. Below the visible atmosphere on both planets the gas density, pressure, and temperature all increase with depth. Temperature rises fast enough to allow convection, the transfer of hot gases from the warm interiors of the planets to their atmospheres. Above the 1 bar level in the atmospheres, the temperature on both planets falls to about -361°F (-218°C) and remains fairly constant until the point where the pressure drops to about 0.01 bars. Above this point, temperature rises with altitude. Despite being farther from the sun, Neptune 's upper atmosphere is warmer at this level than that of Uranus. In addition, this part of the planets' upper atmospheres includes a layer of haze, created when ultraviolet light from the sun destroys methane in the atmospheres and forms complex molecules such as ethane and acetylene.

Weather
Uranus has almost no visible features, and even computer-enhanced images show only small clouds and plumes rotating around it. Because Uranus 's axis is tilted so far, each pole received daylight for half of the planet's 84-year orbit around the sun and lies in total darkness for the other half. Even so, strong winds blow from east to west along the equator and middle latitudes. The atmosphere on Uranus is not very active because the planet has no internal heat source and receives only 0.27 percent of the amount of sunlight that falls on Earth. Neptune receives 2½ times less sunlight than Uranus. It has a less hazy, more complex atmosphere with rapidly changing cloud systems. It also features a Great Dark Spot, much like Jupiter's Great Red Spot. The Great Dark Spot is the size of Earth and rotates counterclockwise with nearby winds blowing at about 7,217 miles per hour (2,200 km) per hour. Other smaller spots and clouds are also visible above Neptune 's surface. As on Uranus, winds on Neptune blow along east-west lines of latitude. Neither planet shows much temperature difference between the poles and the equator, which suggests that each of their atmospheres is very efficient at distributing heat evenly around the planet.

Heat Flow
All the gas giants in the outer solar system are slowly cooling and shrinking, radiating more energy into space than they absorb from the sun. Energy from the warmer interior of each planet is transported by convection to the cooling layers of the atmosphere. Neptune radiates 2.5 times as much energy as it absorbs, while Uranus radiates just 1.1 times as much. However, neither Neptune nor Uranus radiates as much energy into space as predicted by theoretical models of their behavior. This shortfall may be due to slight changes in composition deep within the interiors of each planet. Such changes could hinder the action of convection and thus slow down the rate of cooling.

Interior Structure
Because the interiors of Uranus and Neptune cannot be observed, scientists use theoretical models to predict their characteristics. These models indicate that the atmospheres have about the same composition from their exteriors inward to about 80 to 85 percent of each planet's radius. At this point, the weight of the atmosphere above causes pressures of 300,000 bars and temperatures of 4,940°F (2,727°C). Under these conditions, hydrogen and helium behave more like hot, dense liquids than gases. Below this point, the atmosphere's density increases to about the density of water. This fact suggests a change in composition from a mixture of hydrogen, helium, and methane to a mixture of water, methane, and ammonia. This new composition continues to a point very deep within each planet, and most of the mass of each planet consists of these materials.

Magnetic Fields
Both planets have peculiar magnetic fields. Earth's magnetic field is closely aligned with its axis of rotation, with the north and south magnetic poles close to the north and south geographic poles. On Neptune and Uranus, by contrast, the magnetic fields are tilted far off the axis of rotation. They are also displaced from the center of the planet. Experiments that simulate the atmosphere of Uranus suggest that this difference may be caused by the ability of ices below the planet's crust to conduct electric currents. The electrically conducting regions of Uranus and Neptune may be much closer to their surfaces than those of Earth and the other Jovian planets, and such a circumstance could account for these unusual magnetic fields.

Key Terms
astronomer scientist who studies space and the various bodies it contains density amount of mass (matter that causes an object to have weight) in a unit of volume latitude distance north or south of a planet's equator, measured in degrees

BLUE PLANETS
Both Uranus and Neptune appear blue-green, a color caused by several factors. One factor is that blue light is more easily scattered by atmospheric gases than other wavelengths of light. This process, called Rayleigh scattering after the British scientist who discovered it, also accounts for the blue sky on Earth. Because red light is not so easily scattered, it penetrates more deeply into the atmospheres of Uranus and Neptune, where it is absorbed by methane gas and layers of hydrogen sulfide clouds. Thus, when sunlight is reflected by thee planets' clouds, much of the red light has been removed, and the planets appear blue-green to observers.