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30

For objects on the scale of a planet, the state of matter doesn't really matter much. A colliding planet or planetesimal would not "just pass through" The amount and density of the gas would prevent that. Some easy experiments: Put your hand outside a car as you are driving along, you'll feel that "gas" (ie air) has real substance and ...


21

Rings are made up of tiny (and not so tiny) pieces of rock and ice that are in some way the bits "left over" from the formation of the planet. The theory involves the Roche limit - and is that particles that are already within this limit can't accrete into a larger body because of the tidal forces involved. Another theory is that they are formed when a moon ...


18

Nasa.gov speculates that the most likely possibility is that an object with a mass close to that of Earth's collided with Uranus, causing it to rotate on its side from then on. A recent test by Space.com suggests that "Planet Uranus Got Sideways Tilt From Multiple Impacts". These findings suggest that two or more smaller collisions probably ...


18

According to https://arxiv.org/pdf/1808.01973.pdf, the magnitude of Neptune follows the relationship (formula 17, page 25): $ V = 5 \log_{10} (rd) - 7.00 + 7.944 \times 10^{-3} α + 9.617 \times 10^{-5} α^2 $ Where r is the distance of Neptune to the Sun, d is the distance of Neptune to the observer, and α is “the arc between the Sun and the sensor with its ...


15

NASA's Neptune fact sheet states that Neptune's irradiance is $1.51 W/m^2$. This is roughly three orders of magnitude less than at Earth (at $1367.6 W/m^2$). This sounds like a lot, and it is quite an attenuation. So much that for example solar panels for interplanetary probes are not worthwile at these distances from the sun. However, if you compare this ...


14

Supplementary answer supporting @PierrePaquette thorough and well-source answer: I tried the nice new JPL Horizons interface and fired up Excel which I haven't used in a long time. For years 1800 to 2100 in Observer mode it calculates apparent magnitude using all the bells and whistles (albedo model, phase angle, illumination, etc.) and gives the following ...


13

From wikipedia, the rings of uranus The definitive discovery of the Uranian Rings [...] use[d] the occultation of the star SAO 158687[...] The star SAO 158687, also cataloged as HD 128598 is a magnitude 8.7, orange dwarf star in Libra. There seems to be nothing special about the star, except that one day, a planet passed in front of it.


8

Why does Uranus and Neptune have more methane than Jupiter and Saturn? It's a combination of equations of state (EOS), serpentinization, and mixing (rotational and convective) that favors a preference for some reactions (and resulting compounds) over others. See the references below. The giant planets are all mostly hydrogen and helium, but Uranus and ...


8

The brightness of a Solar System object, seen in reflected light, depends on how far it is from the Sun, $d_s$, and how far away it is from the observer, $d_o$, (and the angles between them). Both dependencies are "inverse square laws": $${\rm brightness} \propto \left(\frac{1}{d_s^2}\right)\left(\frac{1}{d_o^2}\right)\ . $$ Both Uranus and Neptune ...


7

The "strength of gravity" (ie gravitational acceleration) is determined by the mass of the planet and the distance between the planet and the moon. The formula is $$GM/r^2.$$ For the Earth (mass= 1 Earth, distance to moon=390000km) the acceleration is $0.003 ms^{-2}$ For Uranus and Titania (mass =14.5 Earth, distance=435000km) the acceleration is $0.03 ms^...


7

As Miranda is a rather small object (only 235km diameter) it may simply have not enough mass to make it matter settle into hydrostatic equilibrium under the influence of its gravity, thus it basically retains the irregular shape most asteroids have. This nice arxiv paper discusses the mass limits necessary for a stellar body to settle into a nice round shape:...


6

The suspected theory of a giant impact most likely happened during the formation of our Solar System around 3 - 4 billion years ago. It is assumed that an Earth-size or larger proto-planet collided with Uranus. If not all, most of the moons of Uranus were formed after that impact, since such an impact would release a tremendous amount of material into ...


6

The high inclination of the Uranus system to its orbit around the Sun has been known since the satellites were discovered. Lassell 1851 shows Ariel and Umbriel moving at least as far north and south of the planet as they do east and west of it. William Herschel probably noticed the same thing about Titania and Oberon in 1787. When Uranus is at an equinox, ...


6

NASA distinguishes four types of exoplanets: Gas Giant, Super-Earth, Neptune-like, and Terrestrial. The question asks why ice planets termed "Neptune-like" and not "Uranus-like". Let's start with some statistics: What is curious, that (at least according to scholar.google.com), intially more icy exoplanets were termed Uranus like planet ...


5

The inside of a giant planet is not like regular gas. First of all, it is hot. You are away of how it gets hot inside the Earth (causing volcanos). It is also hot inside Jupiter, but since Jupiter is bigger, it is hotter. It would be hot enough to vaporise rock under "normal conditions". The pressure is immense, and things stop behaving as you are used to ...


5

Herschel, the discoverer of the planet named it Georgium Sidus, "George's star" after his patron, King George III of Great Britain. The name was not popular outside of Great Britain, and there were various other proposals. It was Johann Elert Bode who proposed Uranus, the Latin form of the Greek god of the sky. It fits with the existing planets having the ...


4

There is not a single accepted theory as to what caused Uranus' tilt. Rather there are two families of explanations and we still need to collect more data to figure out which is correct. As explained by @Timtech, Uranus' tilt might have been caused by a giant impact. This is supported by simulations showing that an impact might have been violent enough to ...


4

As per the books referred to in comments: Both planets could be resolved as a disk, but no surface features could be observed on either. Spectrograms had been taken, so the general colour of the planets was known. The extreme axial tilt of Uranus was known about. But the relative warmth of Neptune was not.


4

I have found the answer. I just found that venus has an axial tilt of nearly 180 degrees, so I realised that the >90 degree tilts are due to the fact that they are the planets with retrograde rotation, which is equivalent to an 'upside down' (>90 degrees) counter clockwise, normal, rotation.


4

The Nice model of solar system evolution proposes that both Uranus and Neptune migrated outward from their original orbits due to numerous encounters with planetesimals, stimulated by a temporary 2:1 resonance between Jupiter and Saturn. Simulations going back billions of years can put either Uranus or Neptune initially closer to the Sun. Desch 2007, ...


4

In short, No. Side detail: Uranus and Neptune consist likely of 20% gas and 80% rock, coming from simple density considerations. They have large inner cores with masses around $\rm 12-14 \; m_{earth} $, and something like $\rm 2-3 \; m_{earth} $ of gas on top of them. Jupiter and Saturn are true gas giants. They both have $\rm 5-20 \; m_{earth} $ of solids ...


4

The solar perturbations on most of the satellites of Uranus are on a very small scale indeed, which may explain the absence of the instabilities noted in the question. A perturbational effect depends on the scale of the solar perturbing accelerations relative to the ordinary inverse-square attraction of the primary body. The scale factor (often designated ...


4

As said, winds on Uranus are quite strong blowing upto 560 miles/hr (900 kmph). But, the question is what forces drives these winds? Researchers has been digging for quite a while. They investigated the gravity fields of Uranus using data gathered by NASA's Voyager 2 spacecraft and ground-based telescopes. The strength of a planet's gravity field depends on ...


4

There is a science-based approach to explaining the dark spot on Uranus. In 2009 (the image and sighting of the spot in question are from 2006) a paper was published titled: The Dark Spot in the atmosphere of Uranus in 2006: Discovery, description, and dynamical simulations by H.B. Hammel a, L.A. Sromovsky et. al.. In this work they say that the dark spot is ...


4

Disclaimer: This answer is inspired by Magnetic fields of Uranus and Neptune: Metallic fluid hydrogen by Nellis [2017], who explains the center offset of the ice-giants' magnetic fields by contrasting them with Earth's magnetic field. Earth's axisymmetric magnetic field The most researched magnetic field in our Solar System is, of course, Earth. Nellis 2017 ...


4

I started Stellarium on my computer and pressed F6 to bring up the "Location" window. Then I changed the planet to "Uranus", and marvelled at the view of the many rings and many moons from the planet's "surface" For convenience I clicked the buttons to remove the ground and the atmosphere. then I found and clicked on Saturn. It ...


3

Provided that you are the same distance from the centre and you are on or above the surface then the heavier (more mass) planet will have a greater gravitational attraction. It is still possible that the heavier planet has a lower attraction at the surface since it may be bigger. If you can find the mass and radius then you can use the formula that James ...


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