Changes

|albedo=0.51<ref name=ssdhoriz/>

|albedo=0.51<ref name=ssdhoriz/>

|mfd=0.228 G (2.28 * 10^-5 T)<ref name=uranusfact/>

|mfd=0.228 G (2.28 * 10^-5 T)<ref name=uranusfact/>

|pmdm=3 * 10²⁴ N-m/T<ref name=Humphreys2>Humphreys, D. R. "[http://www.icr.org/index.php?module=articles&action=view&page=329 Beyond Neptune: Voyager II Supports Creation]." [[Institute for Creation Research]]. Accessed April 30, 2008</ref>

|pmdm=3 * 10²⁴ N-m/T<ref name=Humphreys2>Humphreys, D. R. "[https://www.icr.org/index.php?module=articles&action=view&page=329 Beyond Neptune: Voyager II Supports Creation]." [[Institute for Creation Research]]. Accessed April 30, 2008</ref>

|cmdm=2.05 * 10²⁵ N-m/T<ref name=Humphreys>Humphreys, D. R. "[http://www.creationresearch.org/crsq/articles/21/21_3/21_3.html The Creation of Planetary Magnetic Fields]." ''Creation Research Society Quarterly'' 21(3), December 1984. Accessed April 29, 2008.</ref>

|cmdm=2.05 * 10²⁵ N-m/T<ref name=Humphreys>Humphreys, D. R. "[http://www.creationresearch.org/crsq/articles/21/21_3/21_3.html The Creation of Planetary Magnetic Fields]." ''Creation Research Society Quarterly'' 21(3), December 1984. Accessed April 29, 2008.</ref>

|mdt=3195 a<ref name=calc>Calculated from observed present magnetic dipole moment and expected magnetic dipole moment at creation.</ref>

|mdt=3195 a<ref name=calc>Calculated from observed present magnetic dipole moment and expected magnetic dipole moment at creation.</ref>

== Rotational characteristics ==

== Rotational characteristics ==

Uranus's sidereal day is 17.24 Earth hours. Uranus's rotation is ''retrograde'' with respect to its orbit around the Sun and the orbits of most of the other planets. Moreover its axis is tilted 97.86° with respect to its orbital plane, so that in a sense the planet is rolling on its side.

Uranus's sidereal day is 17.24 Earth hours. Uranus's rotation is ''retrograde'' with respect to its orbit around the Sun and the orbits of most of the other planets. Moreover, its axis is tilted 97.86° with respect to its orbital plane, so that in a sense the planet is rolling on its side.

== Physical characteristics ==

== Physical characteristics ==

Uranus is a [[gas giant]] having a radius of 25,559 km (15,882 miles). Uranus’s atmosphere is about 83 % [[hydrogen]], 15% [[helium]], and 2% [[methane]]. The methane, more than any other constituent, gives Uranus its color.<ref name=rst/>

Uranus is a [[gas giant]] having a radius of 25,559&nbsp;km (15,882 miles). Uranus's atmosphere is about 83% [[hydrogen]], 15% [[helium]], and 2% [[methane]]. The methane, more than any other constituent, gives Uranus its color.<ref name=rst/>

=== Atmosphere ===

=== Atmosphere ===

=== Orientation of the Uranian system ===

=== Orientation of the Uranian system ===

According to evolutionary theories of how the solar system formed (i.e., the [[nebular hypothesis]]), Uranus's axis should not be tilted 98 degrees with respect to its orbit. Moreover its moons orbit Uranus around its equator, like the hands of a clock around a clock face. Uranus' thirteen rings also are around its equator, so they look vertical. The nebular hypothesis predicts none of these observations.

According to evolutionary theories of how the solar system formed (i.e., the [[nebular hypothesis]]), Uranus's axis should not be tilted 98 degrees with respect to its orbit. Moreover, its moons orbit Uranus around its equator, like the hands of a clock around a clock face. Uranus' thirteen rings also are around its equator, so they look vertical. The nebular hypothesis predicts none of these observations.

Naturalistic [[Astronomy|astronomers]] theorize that Uranus originally formed upright, but suffered a collision with another object, producing its severe tilt. This, however, raises more questions:

Naturalistic [[Astronomy|astronomers]] theorize that Uranus originally formed upright, but suffered a collision with another object, producing its severe tilt. This, however, raises more questions:

# Why is its orbit less eccentric than those of all the other planets except only those of [[Venus]], [[Neptune]], and [[Earth]]?

# Why is its orbit less eccentric than those of all the other planets except only those of [[Venus]], [[Neptune]], and Earth?

# Why is Uranus's orbit less inclined to the ecliptic than is that of any planet except Earth?

# Why is Uranus's orbit less inclined to the ecliptic than is that of any planet except Earth?

# Why are the orbits of Uranus's moons so slightly inclined with respect to Uranus's present equator?<ref name=AiG>Psarris, Spike. "[http://www.answersingenesis.org/creation/v24/i3/uranus.asp Entry for Uranus]." ''Creation'', 24(3):38-40, June 2002. Now hosted by [[Answers in Genesis]]. Accessed April 25, 2008.</ref> Indeed, the vertical orientation of Uranus's moons and of some of its rings was already well-known to astronomers before the Voyager 2 flyby. If the moons formed before the collision, then another series of precisely timed collisions would have been required to change the azimuths of all the orbits, ''and'' the rings&mdash;an absurd violation of [[Occam's razor]]. And if they formed after the collision, then in the absence of any condensing gas cloud, they ought to be inclined at random.

# Why are the orbits of Uranus's moons so slightly inclined with respect to Uranus's present equator?<ref name=AiG>Psarris, Spike. "[http://www.answersingenesis.org/creation/v24/i3/uranus.asp Entry for Uranus]." ''Creation'', 24(3):38-40, June 2002. Now hosted by [[Answers in Genesis]]. Accessed April 25, 2008.</ref> Indeed, the vertical orientation of Uranus's moons and of some of its rings was already well known to astronomers before the Voyager 2 flyby. If the moons formed before the collision, then another series of precisely timed collisions would have been required to change the azimuths of all the orbits, ''and'' the rings&mdash;an absurd violation of [[Occam's razor]]. And if they formed after the collision, then in the absence of any condensing gas cloud, they ought to be inclined at random.

Naturalists try to explain that last by suggesting that Uranus's moons are leftover debris from the collision that tilted its axis. However, Uranus's moons make up only one hundredth of one percent of the mass of the planet, and an impact violent enough to knock the giant over would have produced far more debris than that. (Earth's [[Moon]], also supposed to be the result of a giant collision involving its primary, has a mass of 1.23% that of earth.)<ref name=AiG/><ref name=Psarris>Psarris, Spike. ''Our Created Solar System'' Seattle Creation Conference, 2006.</ref> Moreover, not only are the moons of Uranus oriented well to Uranus's equator, but many of them orbit retrograde to Uranus's own rotation.

Naturalists try to explain that last by suggesting that Uranus's moons are leftover debris from the collision that tilted its axis. However, Uranus's moons make up only one hundredth of one percent of the mass of the planet, and an impact violent enough to knock the giant over would have produced far more debris than that. (Earth's [[Moon]], also supposed to be the result of a giant collision involving its primary, has a mass of 1.23% that of earth.)<ref name=AiG/><ref name=Psarris>Psarris, Spike. ''Our Created Solar System'' Seattle Creation Conference, 2006.</ref> Moreover, not only are the moons of Uranus oriented well to Uranus's equator, but many of them orbit retrograde to Uranus's own rotation.

=== The magnetic field ===

=== The magnetic field ===

The strength of Uranus' magnetic field presented a problem for the evolutionary model when Voyager 2 flew by the planet in 1986. According to the classic dynamo theory, Uranus should not have an appreciable magnetic dipole moment. That it has, did not surprise creationists, because Dr. Russell Humphreys predicted its strength from his own model of the creation of celestial magnetic fields. Humphreys published his model two years before Voyager reconnoitered Uranus.<ref name=Humphreys/><ref name=Humphreys2/>

The strength of Uranus' magnetic field presented a problem when Voyager 2 flew by the planet in 1986. According to the classic dynamo theory, Uranus should not have an appreciable magnetic dipole moment. That it has, did not surprise creationists, because Dr. Russell Humphreys predicted its strength from his own model of the creation of celestial magnetic fields. Humphreys published his model two years before Voyager reconnoitered Uranus.<ref name=Humphreys2/><ref name=Humphreys/>

As mentioned, Uranus' magnetic axis is 60 degrees displaced from Uranus' axis of rotation. It is also displaced from the planet's center by about one-third of the planet's radius. The dynamo theory cannot account for such vast discrepancies. Humphreys' model says nothing about the alignment of a body's magnetic axis with respect to its rotational axis, so these findings do not compromise this model. Humphreys suggests that the displacement results from the asymmetric accretion of additional matter into Uranus' core after the planet's creation. The dynamo theory would have difficulty with this concept, because a dynamo requires a liquid core.<ref name=Humphreys2/>

As mentioned, Uranus' magnetic axis is 60 degrees displaced from Uranus' axis of rotation. It is also displaced from the planet's center by about one-third of the planet's radius. The dynamo theory cannot account for such vast discrepancies. Humphreys' model says nothing about the alignment of a body's magnetic axis with respect to its rotational axis, so these findings do not compromise this model. Humphreys suggests that the displacement results from the asymmetric accretion of additional matter into Uranus' core after the planet's creation. The dynamo theory would have difficulty with this concept, because a dynamo requires a liquid core.<ref name=Humphreys2/>

== Missions to Uranus ==

== Missions to Uranus ==

The only deep-space probe to visit Uranus thus far has been [[Voyager 2]], which flew by Uranus on January 24, 1986. Voyager 2 discovered ten of Uranus's twenty-seven satellites, and two previously unknown rings. Voyager 2 then continued onward to [[Neptune]] before heading out of the [[Solar System]].

The only deep-space probe to visit Uranus thus far has been [[Voyager 2]], which flew by Uranus on January 24, 1986. Voyager 2 discovered ten of Uranus's twenty-seven satellites, and two previously unknown rings. Voyager 2 then continued onward to Neptune before heading out of the Solar System.

== Gallery ==

== Gallery ==