Uranus

2,876,679,082 km from the sun."

The
4 inner planets are the closest to the Sun, and the outer planets are the other four – Jupiter, Saturn, Uranus, and Neptune."

Uranus
has a volume which is about 63 times the volume of Earth which means that 63 Earths can fit inside Uranus."

The planet is often dubbed an ice giant, since 80 percent or more of its mass is made up of a fluid mix of water, methane, and ammonia ices. Unlike the other planets of the solar system, Uranus is tilted so far that it essentially orbits the sun on its side, with the axis of its spin nearly pointing at the star."

In truth, it takes the Earth exactly 23 hours 56 minutes and 4.1 seconds to rotate once on its axis. Meanwhile, on average, a solar day on Earth is 24 hours long, which means it takes that amount of time for the Sun to appear in the same place in the sky."

Uranus orbits the Sun at an average distance (semi-major axis) of 2.875 billion km (1.786 billion mi), ranging from 2.742 billion km (1.7 mi) at perihelion to 3 billion km (1.86 billion mi) at aphelion. Another way to look at it would be to say that it orbits the Sun at an average distance of 19.2184 AU (over 19 times the distance between the Earth and the Sun), and ranges from 18.33 AU to 20.11 AU."

Uranus is made of water, methane, and ammonia fluids above a small rocky center. Its atmosphere is made of hydrogen and helium like Jupiter and Saturn, but it also has methane. The methane makes Uranus blue."

The seventh planet in the solar system — and the largest of the ice giants — Uranus has an atmosphere more comparable with Neptune than with Saturn and Jupiter. Known as ice giants, the two most distant planets from the sun have atmospheres that are heavily dominated by ices. The bizarre orientation of the planet, which orbits the sun tipped on its side, reveals that its inner core has a stronger influence on its weather patterns than the distant ."

The rings of Uranus were the first to be found around a planet other than Saturn. The American astronomer James L. Elliot and colleagues discovered the ring system from Earth in 1977, nine years before the Voyager 2 encounter, during a stellar occultation by Uranus—i.e., when the planet passed between a star and Earth, temporarily blocking the star’s light. Unexpectedly, they observed the star to dim briefly five times at some considerable distance above Uranus’s atmosphere both before and after the planet occulted the star. The dips in brightness indicated that the planet was encircled by five narrow rings. Later Earth-based observations revealed four additional rings. Voyager 2 detected a 10th ring and found indications of others. Outward from Uranus, the 10 are named 6, 5, 4, Alpha, Beta, Eta, Gamma, Delta, Lambda, and Epsilon. The cumbersome nomenclature arose as the new rings were found in places that did not fit the original nomenclature. Characteristics of the rings are given in the table.

Rings of Uranus
name distance from centre of planet (km) observed width (km)* equivalent width (km)**
*The range of values reflects real variations with respect to longitude as well as measurement error.
**Equivalent width is the product of the observed width and the fraction of light attenuated and is given for visible light.
6 41,837 1–2 0.66
5 42,235 2–7 1.23
4 42,571 1–6 1.06
Alpha 44,718 4–11 3.86
Beta 45,661 4–13 3.16
Eta 47,176 1–4 0.64
Gamma 47,627 2–8 3.13
Delta 48,300 3–8 2.69
Lambda 50,026 2–3 0.3
Epsilon 51,149 20–95 42.8
The rings are narrow and fairly opaque. Observed widths are simply the radial distances between the beginning and the end of the individual dimming events. Equivalent widths are the product (more precisely, the integral) of the radial distance and the fraction of starlight blocked. The fact that the equivalent widths are generally less than the observed widths indicates that the rings are not completely opaque. Combining the brightness of the rings observed in Voyager images with the equivalent widths from occultations shows that the ring particles reflect less than 5 percent of the incident sunlight. Their nearly flat reflectance spectrum means that the particles are basically gray in colour. Ordinary soot, which is mostly carbon, is the closest terrestrial analogue. It is not known whether the carbon comes from darkening of methane by particle bombardment or is intrinsic to the ring particles.
The scattering effects on Voyager’s radio signal propagated through the rings to Earth revealed that the rings consist of mostly large particles, objects greater than 140 cm (4.6 feet) across. Scattering of sunlight when Voyager was on the far side of the rings and aiming its camera back toward the Sun also revealed small dust particles in the micrometre size range. Only a small amount of dust was found in the main rings. Most of the microscopic particles were instead distributed in the spaces between the main rings, which suggests that the rings are losing mass as a result of collisions. The lifetime of the dust in orbit around Uranus is limited by drag exerted by the planet’s extended atmosphere and by the radiation pressure of sunlight; the dust particles are driven to lower orbits and eventually fall into the Uranian atmosphere. The calculated orbital lifetimes are so short—1,000 years—that the dust must be rapidly and continually created. Uranus’s atmospheric drag appears to be so large that the present rings themselves may be short-lived. If so, the rings did not form with Uranus, and their origin and history are unknown.


Collisions between the tightly packed ring particles would naturally lead to an increase in the radial width of the rings. Moons more massive than the rings can halt this spreading in a process called shepherding. Certain orbits that lie inside or outside the orbit of a given ring are at the proper radius for a moon in such an orbit to establish a stable dynamic resonance with the ring particles. The condition for the resonance is that the orbital periods of the moon and the ring particles are related to each other in the ratio of small whole numbers. In this kind of relationship, as the moon and the particles pass one another periodically, they interact gravitationally in a way that tends to maintain the regularity of the encounters. The moon exerts a net torque on the ring, and, as the moon and ring exchange angular momentum, energy is dissipated by collisions among the ring particles. The outcome is that the moon and ring particles repel each other. Whichever body is in the outer orbit moves outward, while the one in the inner orbit moves inward. Because the moon is much more massive than the ring, it prevents the ring from spreading across the radius at which resonance occurs. A pair of shepherd moons, one on either side of a ring, can maintain its narrow width.
Voyager 2 found that the innermost two moons, Cordelia and Ophelia, orbit on either side of the Epsilon ring at exactly the right radii required for shepherding. Shepherds for the other rings were not observed, perhaps because the moons are too small to be seen in the Voyager images. Small moons may also be reservoirs that supply the dust leaving the ring system.
Portion of Uranus's ring system with the bright Epsilon ring flanked by its two shepherd moons, Cordelia and Ophelia, in an image obtained by Voyager 2 on Jan. 21, 1986, three days before the spacecraft's closest approach to the Uranian system. Many of Uranus's other rings can be discerned inward of the Epsilon ring.
Portion of Uranus's ring system with the bright Epsilon ring flanked by its two shepherd moons, Cordelia and Ophelia, in an image obtained by Voyager 2 on Jan. 21, 1986, three days before the spacecraft's closest approach to the Uranian system. Many of Uranus's other rings can be discerned inward of the Epsilon ring.
Jet Propulsion Laboratory/National Aeronautics and Space Administration

5 FACTS

• Uranus was officially discovered by Sir William Herschel in 1781."
• Uranus turns on its axis once every 17 hours, 14 minutes."
• from Uranus makes one trip around the Sun every 84 Earth years."
• Uranus is often referred to as an “ice giant planet."
• Uranus is the coldest planets."

REFERENCES

• Retreaved from coolcosmos.ipac.caltech.edu/ask/125-How-big-is-Uranus-
• Retreaved from https://www.space.com/45-uranus-seventh-planet-in-earths-solar-system-was-f...
• Retreaved fromhttps://solarsystem.nasa.gov/planets/uranus/in-depth/

REFERENCES

• Retreaved from https://www.space.com/45-uranus-seventh-planet-in-earths-solar-system-was-f...
• Retreaved from https://solarsystem.nasa.gov/planets/uranus/in-depth/
• Retreaved from http://coolcosmos.ipac.caltech.edu/ask/130-How-long-does-it-take-Uranus-to-...

REFERENCES

• https://www.britannica.com/place/Uranus-planet/The-ring-system
• https://www.space.com/45-uranus-seventh-planet-in-earths-solar-system-was-f...

REFERENCES

• Retreaved from https://spaceplace.nasa.gov/all-about-uranus/en/
• Retreaved fromhttps://spaceplace.nasa.gov/all-about-uranus/en/
• Retreaved fromhttps://space-facts.com/uranus/

REFERENCES

• Retreaved from https://spaceplace.nasa.gov/all-about-uranus/en/
• Retreaved from https://spaceplace.nasa.gov/all-about-uranus/en/
• Retreaved from https://www.space.com/45-uranus-seventh-planet-in-earths-solar-system-was-f...