Uranus And Neptune – Icy Blues!

Discussion in 'Education & Personal Growth' started by kkrish, Aug 26, 2018.

  1. kkrish

    kkrish IL Hall of Fame

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    Uranus and Neptune are the same size and have the same composition. They both, because of their large distance from the sun contain more methane and ammonia ice. These two are therefore termed as ice giants while Jupiter and Saturn are known as gas giants.


    Uranus (you-ran-us)

    wikipedia.jpg
    Image source: Wikipedia

    This greenish-blue planet could have been named Georgium Sidus if William Herschel, who discovered the planet in 1781, had his way. The world had other plans though and named this planet Uranus after the Greek god of the sky.

    Uranus is the father of Cronus (Saturn) and grandfather of Zeus (Jupiter)

    The seventh planet is 19.8 AUs from the sun. This is 2.9 billion kilometers away and takes sunlight two hours and 40 seconds to reach the planet. This was the first planet to be discovered with the help of a telescope.

    A radioactive element was discovered in 1789, eight years after this planet was discovered and we got Uranium, named after this planet.

    Uranus appears to have found something funny, or so it appears to be. This planet, instead of spinning on its axis upright or slanted (like our Earth) appears to be ROFL (rolling on the floor). This is because its axis is parallel to its elliptical plane. Scientists believe that some huge collision must have caused the planet to “fall down on its side”.

    The Sideways rotation means extreme seasons on the planet. So at the planet’s North Pole, it is 21 years daytime in summer, 21 years of night in winter, and 42 years of day and night in the spring and fall.

    This is the only other planet next to Venus to rotate from East to West known as retrograde rotation

    It takes the planet 84 Earth years to complete one orbit around the Sun. The planet spins at the rate of 17 hours per rotation.

    The planet is about four times wider than the Earth. If Earth is the size of an apple, Uranus would be the size of a basketball.

    Uranus formed about 4.5 billion years ago when our solar system formed. At first it was close to the sun but slowly moved away about 4 billion years ago to its current position.

    About 80% of this planet is made up of a hot dense fluid of "icy" materials—water, methane and ammonia—enclosing a small rocky core. Near the core, the temperature is 4,982 degrees Celsius. It gets its greenish-blue color from the methane present in its atmosphere.

    Uranus does not have a true surface as the planet is full of swirling fluids. A spacecraft would have no place to land and if it flew inside the swirling fluids it would be destroyed by the extreme pressure and temperatures of the fluids.

    Till date Voyager 2 is the only spacecraft that has flown by this planet.

    Uranus has 13 known rings. The inner rings are narrow and dark and the outer rings are brightly colored.

    Recently scientists have confirmed that Uranus stinks. That’s because there is a lot of hydrogen-sulfide (H2S) in the planet’s upper atmosphere and we all know that H2S stinks like rotten eggs. Not that any human is going to descend on Uranus, and even if one does, he/she cannot really sniff at the atmosphere. To really smell the atmosphere one has to remove the space-helmet which is a definite “no, no!”

    Magnetosphere

    Usually magnetic fields are aligned with their planets’ rotation. However, Uranus’ magnetic field is tilted by about 60 degrees from its rotational axis. Not only is the magnetic field tilted but also is offset from the planet’s center by about a third of its radius.

    Due to the lopsided magnetic field auroras on Uranus are not in line with its poles.

    Atmosphere

    A great dark spot and a small dark spot were the only two clouds that Voyager 2 saw during its flyby in 1986, more recent observations reveal that more such clouds are present as the planet reaches its equinox.

    Though Uranus is closer to the Sun than Neptune, at some places its atmosphere is -224.2 Celsius (49K) which is even colder than Neptune.

    With very strong winds reaching up to 900 kilometers per hour, these winds blow in the reverse direction of the planet’s rotation at the equator (retrograde) and closer to the poles they blow in the rotational direction (prograde).

    Moons

    Miranda, Juliet, Puck, Ophelia, Rosalind, Cressida, Belinda… no we have not moved to Shakespeare’s works. We are talking about the Uranus’ moons. The moons are all named after Shakespeare’s and Alexander Pope’s characters, moving away from the traditional practice of names from Roman and Greek mythology.

    Uranus has 27 known moons and most of the inner moons appear to be ice and rock, while the composition of the outer moons still remain a mystery.

    Rings

    Uranus has two sets of rings. The inner system of nine rings consists mostly of narrow, dark grey rings. There are two outer rings: the innermost one is reddish like dusty rings elsewhere in the solar system, and the outer ring is blue like Saturn's E ring.

    In order of increasing distance from the planet, the rings are called Zeta, 6, 5, 4, Alpha, Beta, Eta, Gamma, Delta, Lambda, Epsilon, Nu and Mu. Some of the larger rings are surrounded by belts of fine dust.

    contd...
     
    Last edited: Aug 27, 2018
  2. kkrish

    kkrish IL Hall of Fame

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    Neptune

    fig1.jpg

    Image courtesy: aasnova.org

    Named after the Roman god of the sea, Neptune is the only planet that was first discovered based on mathematical calculations. Its presence was predicted by Urbain Le Verrier, and Johann Galle discovered the planet in 1846. The name, Neptune, was suggested by Le Verrier

    The last planet in our Solar System, Neptune, in 2011 completed its orbit around the Sun since its discovery in 1846. So our birthday, if we lived in Neptune, will be once every 165 Earth years.

    Though this is the last planet, sometimes Neptune is even farther from the Sun than dwarf planet Pluto (every 248 Earth years to be precise) because of Pluto’s elliptical and erratic orbit and this last for 20 years.

    Neptune spins quite fast and one day on this another blue planet is 16 hours.

    Dark, cold, and with supersonic winds whipping about, Neptune is 30 times further from Sun than Earth is from the sun (30 AU), at a distance of 4.5 billion kilometers.

    It takes sunlight four hours to reach the planet. The sunlight is so far away that noon on Neptune would be like twilight on Earth. That dim. In other words, we receive about 900 times the brightness than does Neptune.

    The windiest of all the planets in our Solar system, frozen methane is whipped across the planet at speeds more than 2,000 km/h. Compare it to Earth’s most powerful winds which are a maximum of 400km/h.

    Neptune’s diameter is four times wider than Earth’s. If Earth were an apple, Neptune would be a basketball.

    Neptune has a small rocky core surrounded by hot and dense “icy material” - water, methane, and ammonia and its atmosphere is mostly molecular hydrogen, atomic helium and methane.

    Till date Voyager is the only spacecraft that has flown by this planet that has six known rings, and 13 moons named after Greek mythological sea gods and nymphs. Triton is its largest moon and this moon is the only one in our solar systems that revolves around its planet retrograde. Scientist therefore believe that Triton could have been an independent object captured by Neptune’s gravity.

    Neptune’s axis of rotation is tilted 28 degrees with respect to the plane of its orbit around the Sun, which is similar to the axial tilts of Mars and Earth. This means that Neptune experiences seasons just like we do on Earth; however, since its year is so long, each of the four seasons lasts for over 40 years.

    Magnetosphere

    The main axis of Neptune's magnetic field is tipped over by about 47 degrees compared with the planet's rotation axis. Like Uranus, whose magnetic axis is tilted about 60 degrees from the axis of rotation, Neptune's magnetosphere undergoes wild variations during each rotation because of this misalignment. The magnetic field of Neptune is about 27 times more powerful than that of Earth.

    Atmosphere

    Neptune's atmosphere is made up mostly of hydrogen and helium with just a little bit of methane. Neptune's neighbor Uranus is a blue-green color due to such atmospheric methane, but Neptune is a more vivid, brighter blue, so there must be an unknown component that causes the more intense color.

    In 1989 a large, oval-shaped storm in Neptune's southern hemisphere dubbed the "Great Dark Spot" was large enough to contain the entire Earth. That storm has since disappeared, but new ones have appeared on different parts of the planet.

    The Latest: NASA's Hubble Space Telescope confirmed the presence of a dark vortex in the atmosphere of Neptune. Though similar features were seen during the Voyager 2 flyby of Neptune in 1989 and by the Hubble Space Telescope in 1994, this vortex is the first one observed on Neptune in the 21st century.

    Neptune's dark vortices are high-pressure systems and are usually accompanied by bright "companion clouds," which are also now visible on the distant planet. The bright clouds form when the flow of ambient air is perturbed and diverted upward over the dark vortex, causing gases to likely freeze into methane ice crystals.
     
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  3. kkrish

    kkrish IL Hall of Fame

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    The Voyager pictures of Uranus show it as a pale greenish blue planet and Neptune as a vivid blue planet. It is said that both were color enhanced to show the difference, and that both are very pale blue planets. Uranus gets about 1/400 of the light and Neptune is even dimmer, because it get 1/900 the light.

    Source:
    nasa.gov
    Simpleastronomy.blogspot.com.
     
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  4. Gauri03

    Gauri03 Moderator Staff Member IL Hall of Fame

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    I'd been waiting for this ever since you hinted you had been working on a new article. Interesting read, as always, on the two lesser known, weird cousins of the solar system. I have updated the index though I do hope this won't be the last time. There is a vast universe outside the solar system! : )
     
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  5. kkrish

    kkrish IL Hall of Fame

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    Thank you @Gauri03 .
    I sincerely appreciate your help.

    No, you job of giving links in the sticky thread is not yet over. :biggrin:

    There is more in the solar system, and I have many more beyond also, lined up before I say, "done" :)
     
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  6. Gauri03

    Gauri03 Moderator Staff Member IL Hall of Fame

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    I am more than happy to be of use. Keep them coming! :thumbup:
     
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