45 votes
Accepted

Why wasn't the planet Uranus recognized by ancient cultures?

The source of light that is Uranus was observed as far back as 128 BC. However it was misidentified as star as late as the 1760's. Then it was observed by Herschel in 1781, who also misidentified it,...
StephenG - Help Ukraine's user avatar
43 votes

Why is Uranus called a "green planet"?

I think your issue is linguistic not astronomical. The way a language cuts up the space of colours into discrete names is varies strongly from one language to another, and even from one dialect to ...
James K's user avatar
  • 121k
30 votes
Accepted

How is it possible for a collision to be responsible for Uranus's axial tilt?

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 ...
James K's user avatar
  • 121k
28 votes

Why is Neptune a darker blue than Uranus?

This is an intriguing question, with a solution suggested by the Irwin et al. (2022; arXiv:2201.04516) paper that inspired the YouTube, NewScientist, ScienceAlert, Phys.org, etc. coverage of the past ...
giardia's user avatar
  • 2,088
27 votes

Why wasn't the planet Uranus recognized by ancient cultures?

I like ScienceSnake's comment - a combination of faintness and its comparatively small apparent motion. It was observed in 1690 by John Flamsteed on several occasions, but because it moved so little ...
Bumptious Q Bangwhistle's user avatar
26 votes
Accepted

Are spacecraft visits to Uranus and Neptune hard to plan?

Uranus and Neptune are far - in orders of light-hours away. It took Voyager 2 nearly a decade to reach Uranus since its launch, costing almost $1B to build it in the first place. It's not that we can'...
4NT4R3S's user avatar
  • 899
20 votes
Accepted

Could Neptune be viewed with the naked eye from Uranus?

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}...
Pierre Paquette's user avatar
17 votes

How am I supposed to locate the planets Uranus and Neptune with a 70 mm f/5.7 refractor?

Right now you won't. Both are on the "wrong" side of the sun and so not easily observable from Earth. At the moment (early 2020s) they are in the constellation of Aries and Pices which are ...
James K's user avatar
  • 121k
17 votes

Why is Uranus called a "green planet"?

This answer looks into why Uranus is "green" or at least greener compared with Neptune's blue. Both planets have similar atmospheric compositions and would ordinarily be expected to show ...
Oscar Lanzi's user avatar
  • 1,113
15 votes

Why wasn't the planet Uranus recognized by ancient cultures?

It would require a lucky coincidence As noted by others, Uranus is faint and easy to misidentify as a fixed star. However, Bourtembourg 2013 claims that Uranus was observed already in 128 BC by ...
Martin Modrák's user avatar
14 votes

Could Neptune be viewed with the naked eye from Uranus?

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 ...
uhoh's user avatar
  • 31.1k
13 votes

Which star did Uranus occult in 1977 when the planet's rings were discovered?

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 ...
James K's user avatar
  • 121k
10 votes
Accepted

Why was Neptune rather than Uranus chosen as an archetype?

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". ...
B--rian's user avatar
  • 5,616
10 votes

Why is Neptune a darker blue than Uranus?

Tl:DR: According to a team led by planetary physicist Patrick Irwin of the University of Oxford in the UK, an extended layer of haze dilutes the hue of Uranus, resulting in a paler color compared to ...
Nilay Ghosh's user avatar
  • 4,462
9 votes

Could Neptune be viewed with the naked eye from Uranus?

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 ...
ProfRob's user avatar
  • 152k
8 votes
Accepted

Why do Uranus and Neptune have more methane than Jupiter and Saturn?

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 ...
Rob's user avatar
  • 2,646
8 votes

Why is Uranus called a "green planet"?

This is just a mere illusion. In reality, the peak wavelength is actually between green and blue, that is slightly cyanish/turquoise. The reason this happens is because the atmosphere of Uranus ...
Arjun's user avatar
  • 1,256
7 votes
Accepted

Does Uranus have a stronger gravitational pull on its moons than Earth does?

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 ...
James K's user avatar
  • 121k
6 votes

Uranus' axis of rotation-when discovered?

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 ...
Mike G's user avatar
  • 18.7k
6 votes
Accepted

Why was Uranus named what it was?

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 ...
James K's user avatar
  • 121k
6 votes

If the axial tilt of Uranus (97°) was caused by a giant impact, then why do its moons orbit around its equator at the same tilt (≈97°)?

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 ...
H.Aziz Kayıhan's user avatar
6 votes

Calculating net gravitational force on Uranus

In the particular case of Uranus, (and considering Uranus and its moons a single system) You only need to consider the Sun + perturbations by the other outer planets. As a more general procedure, ...
James K's user avatar
  • 121k
6 votes
Accepted

Is Uranus the farthest object in Solar System that you can see with naked eyes?

Yes, apart from maybe Neptune, which is within the "extreme naked eye limit", there are no other objects further than Uranus that have an apparent magnitude above +8. See this list: https://...
Rabbi Kaii's user avatar
6 votes

Why is Uranus called a "green planet"?

A convenient pattern Uranus’ color is somewhere between green and blue. Since a lot of space trivia is in the purview of elementary education, and since patterns are useful for memorizing, it’s ...
Spencer Joplin's user avatar
5 votes
Accepted

What is the underlying nature of the dark spot found on Uranus?

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 ...
Wilhelmroentgen's user avatar
5 votes

Aren't there any rock or similar firm material on/in the gas giant planets?

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 ...
James K's user avatar
  • 121k
5 votes

Why is Uranus called a "green planet"?

Although both Uranus and Neptune exhibit a color palette ranging from deep blue to pale green, there is a prime difference in the atmospheric composition which determines the color difference. In the ...
Nilay Ghosh's user avatar
  • 4,462
5 votes
Accepted

Why are heavier hydrocarbons not present in lower part of Uranian atmosphere?

Methane is more abundant in the thermosphere and the stratosphere. On the stratosphere, the Wikipedia article you cite says The most abundant stratospheric hydrocarbons after methane... Also note ...
ProfRob's user avatar
  • 152k

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