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103 votes
Accepted

Did I see Pluto with my naked eye?

Pluto is something like magnitude 14. The limit for the human vision is somewhere between magnitude 6 (widely accepted) and 8-ish (highly trained observers with perfect vision in ideal conditions ...
Florin Andrei's user avatar
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
  • 19.9k
18 votes

Did I see Pluto with my naked eye?

As Florin correctly stated, it can't have been Pluto. You have probably looked at it and you have even gotten its light in your eyes. That little itty bitty shine just has no chance to make your ...
Haunt_House's user avatar
17 votes
Accepted

How bright is it on Pluto in the middle of the day?

Back when New Horizons was preparing for its flyby back int 2015, NASA's website set up a tool to allow you to experience the brightness of light at High Noon on the subsolar point on Pluto. From ...
notovny's user avatar
  • 4,788
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
16 votes

How close will Pluto come to Earth this year (2024)?

As far as I see, the separation between Earth and Pluto this year is always bigger than 34.045586 AU (5,093,147,172 km). This minimum separation is reached on 20th July 2024 around 21h UTC checked to ...
planetmaker's user avatar
  • 19.9k
10 votes

How close will Pluto come to Earth this year (2024)?

In the interest of comparison, here is a small Python script to compute the moment of closest approach of Pluto to the geocenter using astropy.coordinates.get_body()...
Roy Smart's user avatar
  • 1,612
9 votes

What is the resolution in megapixels of the Hubble Telescope?

The size of the cameras that took the Pluto pictures is easy enough to find: the ACS Wide Field Camera has two 2K by 4K (hence 8 Mega pixel) CCDs, with a field of view of 202×202 arcsec. The high ...
ProfRob's user avatar
  • 153k
8 votes
Accepted

What was the definition of a planet before August 24, 2006?

What was the definition of a planet before August 24, 2006? I think this deserves a bit more of an answer because it's not quite so simple. Yes, it's true that there was no formal definition of what ...
userLTK's user avatar
  • 24.1k
8 votes
Accepted

What's the temperature of Pluto's core?

TL;DR: 1000 K (according to differentiated model of Pluto) According to the density value of Pluto, astronomers proposed three types of structural models: Undifferentiated or "cold" model: ...
Nilay Ghosh's user avatar
  • 4,691
8 votes

How bright is it on Pluto in the middle of the day?

These two calcs agree pretty well: The Sun's magnitude from from Pluto is -18.7 m = -18.75 magnitudes That's quite a bit brighter than a full moon, so you'd be able to read by it.
Wayfaring Stranger's user avatar
7 votes
Accepted

Is Pluto a "proto-planet"?

The question says a few interesting things: The system orbit isn't on the ecliptic The system hasn't cleared its neighbourhood These are not going to change in the next few million years - or ever. ...
Andy's user avatar
  • 2,467
6 votes

Is the point of this paper to say that Pluto's status as a planet should have been handled scientifically, rather than by a vote?

Part of the problem here is semantics. The meaning of "planet" was really poorly defined prior to 2006 (and some argue that it still is). In the early 2000's, this started to become an issue. You ...
J.M. Haynes's user avatar
  • 1,058
6 votes
Accepted

How many solar system objects that can really qualify as a KBO are likely to enter Pluto's Hill sphere each day?

The Hill sphere radius of Pluto is about $r$ = 6 million km. Most of the Kuiper belt is in prograde motion around the Sun (like Pluto). Pluto's average speed is under a lazy 5 km/s for an orbital ...
Connor Garcia's user avatar
  • 16.3k
6 votes
Accepted

Why does Wikipedia state that the Solar System has one unconfirmed planet?

That was a rather recent (16 January 2021) change to that wiki page made by a user named Mariofeds, who does not have a wikipedia user page and who has just one contribution to wikipedia. It may well ...
David Hammen's user avatar
  • 34.1k
6 votes

why the difference in resolution for images of Pluto?

Basically you say it yourself: The reason is in the flyby itself. One doesn't cover every part of the surface with equal resolution when just passing by. Some parts (as seen in the lower part of the ...
planetmaker's user avatar
  • 19.9k
6 votes

why the difference in resolution for images of Pluto?

"Short" Version: The New Horizons flyby of the Pluto-Charon system took place at a little over 14 km/sec. The images used in that mosaic include the highest resolution images that were ...
Stuart Robbins's user avatar
6 votes

How close will Pluto come to Earth this year (2024)?

Distance and time are not simple concepts in astrodynamics! Checking Horizons, I found that if we calculate vectors to Pluto using Earth's geocenter as the origin, we can get several answers. First, ...
uhoh's user avatar
  • 30.8k
6 votes

How close will Pluto come to Earth this year (2024)?

As I mentioned in a comment, according to JPL Horizons the minimum centre-to-centre distance from Earth to Pluto this year is 5,093,180,949 km at 2024-Jul-20 14:20:51 UTC. Here's a Horizons query with ...
PM 2Ring's user avatar
  • 14.9k
5 votes

Will Pluto ever clear its path?

In addition to the answer above, Pluto is a Neptune crossing trans neptunium object or TNO as it's often abreviated. Being a TNO doesn't exclude the possibility of an object being a planet but ...
userLTK's user avatar
  • 24.1k
5 votes

How bright is it on Pluto in the middle of the day?

From Pluto, the Sun is point-like to human eyes, but still very bright, giving roughly 150 to 450 times the light of the full Moon from Earth (the variability being due to the fact that Pluto's orbit ...
Ivan Borsuk's user avatar
5 votes

Can New Horizons probe turn back and start orbiting Pluto

A Pluto orbiter would have been possible, but then the entire mission would have to be designed around that. New Horizons was designed as a small fast probe that could reach Pluto relatively quickly (...
JanKanis's user avatar
  • 571
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
4 votes
Accepted

How much are Neptune's and Uranus' orbits perturbed by Pluto and other KBOs?

Since (1) the mass of the Pluto/Charon system is very small compared with Neptune, and (2) their orbits are in 2:3 resonance, so the perturbation of Neptune's orbit would have been undetectable. ...
Professor O's user avatar
4 votes
Accepted

What other definitions for a planet were proposed?

The IAU website has this draft definition of "planet" and "plutons" page, published on 16 August 2006 in Prague. It says (emphasis mine): The world's astronomers, under the ...
Jean-Marie Prival's user avatar
4 votes

Does Pluto's atmosphere collapse?

Found this link by Emily Lakdawalla, she wrote a detailed explanation about Pluto`s seasons and its movement thru the solar system. Here research seems to contradict the atmosphere collapse and and ...
JanErik's user avatar
  • 85
4 votes

Is the point of this paper to say that Pluto's status as a planet should have been handled scientifically, rather than by a vote?

To respond to the question as is: yes the paper is trying to point out that the concensus was not scientific. However, this claim is not true at all. In order to understand how classifications within ...
H.Aziz Kayıhan's user avatar
3 votes

Is the point of this paper to say that Pluto's status as a planet should have been handled scientifically, rather than by a vote?

If they wanted to make this paper about Pluto, why would they not just discuss Pluto? You may be right that the comment about voting could be linked to the Pluto debate, but I don't see any reason ...
FJC's user avatar
  • 1,324
3 votes

Why are rocky and small planets nearer to the Sun whereas big, gas giants are farther?

The planets all have differences based on where they are and their compositions. The outer gas giants are so large today because of how quick they were to accrete material. In a protoplanetary disk, ...
t.sand's user avatar
  • 122

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