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31 votes
Accepted

Can Pluto be seen with the naked eye from Neptune when Pluto and Neptune are closest?

No, it cannot. Far from it. The closest approach between both planets is roughly 16 AU due to the 3:2 orbit resonance. Pluto will even then be a tiny dot among many with a brightness around 14 mag. ...
planetmaker's user avatar
  • 19.5k
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
26 votes
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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
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20 votes
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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
  • 123k
17 votes
Accepted

What is this bright blue object taken by the Webb telescope?

That is Triton, Neptune's moon. The colours are false, since the JWST is an infrared telescope. Triton is an unusual object and probably didn't form with Neptune. Instead, it is likely a captured ...
James K's user avatar
  • 123k
16 votes

Why does Neptune only have one major moon?

It seems possible that Neptune once had a system of moons similar to other outer planets. However Triton, a Kuiper belt object was captured by Neptune, and this disrupted the existing moons. It would ...
James K's user avatar
  • 123k
16 votes

Can Pluto be seen with the naked eye from Neptune when Pluto and Neptune are closest?

According to the NASA Pluto fact sheet, the brightest that Pluto gets is an apparent visual magnitude of 13.65 when it is 28.6 au from the Earth and (presumably) about 29.6 au from the Sun. To work ...
ProfRob's user avatar
  • 153k
14 votes

Have there been successful attempts at spotting Neptune with the naked eye?

Well, having seen Neptune and identifying Neptune are two totally different things. Let's tackle this one step at a time. Your link says: From these observations it would appear that, if seen upon ...
Sir Cumference'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
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12 votes
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How fast is Neptune getting brighter? When was was this first noticed and reported?

TL;DR: There was apparent 11% increase of Neptune brightness during 1980 and 2000. This could be due to multiple reasons. Recent observation suggested the reason to be change in the amount and ...
Nilay Ghosh's user avatar
  • 4,462
10 votes
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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
  • 153k
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
  • 2,656
8 votes

Do tides occur on planets like Neptune, having water?

There will be tides, but they will be not very large. It's pretty easy to get a good estimate of their size. There are two things that control tides on Earth and both will be present anywhere else: ...
Mark Olson's user avatar
  • 7,640
7 votes

Do tides occur on planets like Neptune, having water?

Neptune's largest moon, Triton, is about a third the mass of Earth's moon, and roughly the same distance away from its primary, so it will indeed have noticeable tidal effect on Neptune's atmosphere ...
Russell Borogove's user avatar
7 votes
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When was the last time a total solar eclipse on Neptune courtesy of Triton occured, and when will be the next?

According to Wikipedia, all of Neptune's inner moons can cause solar eclipses. At that distance, "the Sun's angular diameter is reduced to one and a quarter arcminutes across". Triton has an ...
PM 2Ring's user avatar
  • 14.8k
6 votes
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What are those blobs in each of the two bright rings of Neptune shown in the new JWST image?

This photo captures 7 of the 14 moons of Neptune. The ones you pointed out are Despina on the right and Galatea on the left as illustrated by this NASA website. Now the reason why they seem to ...
DialFrost's user avatar
  • 2,115
6 votes
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How do I know that I’ve found Neptune?

Neptune is a tricky one: its color is not very different from a type A star, and its angular diameter is only twice that of the Airy disk of a star in a 20cm reflector. Even with good optics in good ...
Mike G's user avatar
  • 18.7k
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
  • 123k
5 votes
Accepted

Why is the eccentricity of Triton so low?

Tidal circularization is indeed a plausible mechanism for why Triton's orbital eccentricity is so low, and I believe it is in fact the prevailing theory, at the moment. In short, tidal forces from ...
HDE 226868's user avatar
  • 36.6k
5 votes

Diamonds in Neptune?

People have demonstrated high-pressure diamond formation using laser-driven shocks, much in line with the original idea. The diamond rain idea seems to be doing well (popular science article about it, ...
Anders Sandberg's user avatar
5 votes

Can Pluto be seen with the naked eye from Neptune when Pluto and Neptune are closest?

That's great question! ... I'm just thinking that just for comparison, Pluto is roughly 70% the diameter of our Moon and Pluto would be far away from Neptune than the Moon is from Earth. Moon is also ...
Daniel Morales's user avatar
5 votes
Accepted

Dates of Passage of Neptune at Aphelion and Perihelion

The last perihelion passage of the Neptune system barycentre relative to the Solar System barycentre (SSB) was at 1881-Feb-02 10:00 TDB. Here's a plot (courtesy of JPL Horizons) of the distance from ...
PM 2Ring's user avatar
  • 14.8k
5 votes
Accepted

How close to Neptune would I have to be to see it with the naked eye?

Fortunately, Neptune is in an almost circular orbit that is almost in the same plane as that of the Earth. The NASA planetary fact sheet has Neptune at an apparent magnitude of 7.7 when it is $4.35\...
ProfRob's user avatar
  • 153k
4 votes

How fast is Neptune getting brighter? When was was this first noticed and reported?

This is an incomplete answer—a placeholder for a more complete answer that I'm adding here at the request of the OP (who, I will say, has been very patient with me!). Although the precise reasons aren'...
Brian Tung's user avatar

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