#Tag · bonfire.cafe

In 1964, the first simulation showing that Pluto is in a mean-motion resonance with Neptune was published: https://articles.adsabs.harvard.edu/pdf/1965Obs....85...43C

They ran a 120,000 year simulation that showed libration of the resonant angle for the first time. This must have been terrifyingly hard to do. Punch cards, vacuum tubes, FORTRAN? I don't even know how they did this, but it was run on the Naval Ordnance Research Calculator

This was the first time Pluto's orbital stability was explained.

A figure from a paper showing Pluto's motion relative to Neptune's over 120,000 years. Pluto makes almost a circle, but with two little loops 90 degrees from Neptune's position.

A man is retired.

@Photo55@mastodon.social replied · 3 days ago

@sundogplanets
In 1966 #LarryNiven a SciFi author in #WorldOfPtavvs had #Pluto a moon of Neptune, long previously hit by a spaceship at relativistic speed aimed at #Neptune An artifact protected by a plot device remained on it.

He would have been aware of that work I think.

Good story, although the usual elements wouldn't do this century.

Ross 🏳️‍🌈🏴 boosted

Bits of Pluto

@bitsofpluto@mastodon.cesium.pw · 2 months ago

A bit of Pluto
#pluto #nasa #space #astronomy #science #plutopics

Bits of Pluto

@bitsofpluto@mastodon.cesium.pw · 2 months ago

A bit of Pluto
#pluto #nasa #space #astronomy #science #plutopics

Bits of Pluto

@bitsofpluto@mastodon.cesium.pw · 2 months ago

A bit of Pluto
#pluto #nasa #space #astronomy #science #plutopics

Global Museum

@globalmuseum@mastodon.online · 2 months ago

Pluto’s ice mountains, frozen plains and layers of atmospheric haze backlit by a distant sun, as seen by the New Horizons spacecraft.

📸: NASA/JHUAPL/SwRI @wonderofscience #globalmuseum #Space #Pluto

GIF

Alan Boyle

@alanboyle@mastodon.social · 3 months ago

The last novel in the Grand Tour series by sci-fi master #BenBova is #Pluto, which reflects the latest discoveries from the #NASA #NewHorizons mission. As the author of "The Case for Pluto," I was tickled to talk with space scientist Les Johnson, who wrote the novel based on the notes that Bova left behind when he died. Give a listen to the #FictionScience podcast to get the full details. https://cosmiclog.com/2025/10/31/a-fictional-grand-tour-portrays-pluto-as-it-really-is/

alcinnz boosted

ftg

@ftg@mastodon.radio · 3 months ago

New toy.
I could not resist.

#sdr #pluto #plutoplus

Black pcb with an AMD Zynq 7020 FPGA and analog devices RF transceiver.

ftg

@ftg@mastodon.radio · 3 months ago

New toy.
I could not resist.

#sdr #pluto #plutoplus

Kurt Kremitzki

@kkremitzki@mastodon.social · 4 months ago

The whole "grumbling about #Pluto not being a #planet" anymore discourse bugs me, because it was not really a demotion, it was the inspiration for and promotion into a special class which elevates many other celestial bodies, especially including #Ceres, which is Very Cool and Not So Far https://en.wikipedia.org/wiki/Ceres_(dwarf_planet)

The dwarf planet Ceres, mostly a dusty gray marked by craters and a few bright spots hinting at an interesting composition.

Ceres (dwarf planet) - Wikipedia

AkaSci 🛰️

@AkaSci@fosstodon.org · 5 months ago

New definition for planet proposed by Prof. Jean-Luc Margot at the IAU in Aug 2024:
A planet is a celestial body that
1. orbits one or more stars, brown dwarfs or stellar remnants and
2. is more massive than 10^23 kg and
3. is less massive than 13 Jupiter masses (2.5 X 10^28 kg).

The new definition applies to exoplanets as well.

But, Pluto at 1.31 x 10^22 kg, will still fail to gain planetary status.

Next IAU GA - 2027, Rome.

https://newsroom.ucla.edu/releases/proposal-to-change-scientific-definition-of-planet
https://iopscience.iop.org/article/10.3847/PSJ/ad55f3
#Pluto
3/n

Pic from the IAU General Assembly (GA) 2024 in Cape Town.
Source: https://astronomy2024.org/resolutions-to-be-voted-on-at-the-upcoming-xxxii-general-assembly/ — Pic from the IAU General Assembly (GA) 2024 in Cape Town. Source: https://astronomy2024.org/resolutions-to-be-voted-on-at-the-upcoming-xxxii-general-assembly/

AkaSci 🛰️

@AkaSci@fosstodon.org replied · 5 months ago

Here is a more precise but more complex proposal in the paper for the definition of a planet.

Unfortunately, the IAU in the 2024 meeting did not post the proposal ahead of time and asked the authors to present it to have a large discussion and consensus before doing anything else.

The authors state that meaningful action on the proposal does not appear likely until the next IAU General Assembly in 2027 in Rome at the earliest.

https://iopscience.iop.org/article/10.3847/PSJ/ad55f3
#Pluto
3/n

Snippet from paper about the more precise definition of a planet -

A planet is a celestial body that
(a) orbits one or more stars, brown dwarfs, or stellar remnants, and

(b) has sufficient mass to dynamically dominate the neighborhood around its orbit, i.e., m > 0.0012 (mcentral)^(5/8) a^(9/8), where m is the mass of the planetary body expressed in Earth masses, mcentral is the mass of the central body expressed is solar masses, and a is the semimajor axis expressed in astronomical units, and

(c) has sufficient mass for its self-gravity to overcome rigid body forces so that it is approximately in hydrostatic equilibrium and assumes a nearly triaxial shape, i.e., m > 10^21 kg, and

(d) has a true mass below the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity), and

(e) has a mass ratio with the central object below the L4/L5 instability, i.e., m/mcentral < 2/(25 + √621) ≃ 1/25.

A satellite is a celestial body that orbits a planet. — Snippet from paper about the more precise definition of a planet - A planet is a celestial body that (a) orbits one or more stars, brown dwarfs, or stellar remnants, and (b) has sufficient mass to dynamically dominate the neighborhood around its orbit, i.e., m > 0.0012 (mcentral)^(5/8) a^(9/8), where m is the mass of the planetary body expressed in Earth masses, mcentral is the mass of the central body expressed is solar masses, and a is the semimajor axis expressed in astronomical units, and (c) has sufficient mass for its self-gravity to overcome rigid body forces so that it is approximately in hydrostatic equilibrium and assumes a nearly triaxial shape, i.e., m > 10^21 kg, and (d) has a true mass below the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity), and (e) has a mass ratio with the central object below the L4/L5 instability, i.e., m/mcentral < 2/(25 + √621) ≃ 1/25. A satellite is a celestial body that orbits a planet.

AkaSci 🛰️

@AkaSci@fosstodon.org · 5 months ago

The new definition applies to exoplanets as well.

But, Pluto at 1.31 x 10^22 kg, will still fail to gain planetary status.

Next IAU GA - 2027, Rome.

https://newsroom.ucla.edu/releases/proposal-to-change-scientific-definition-of-planet
https://iopscience.iop.org/article/10.3847/PSJ/ad55f3
#Pluto
3/n

AkaSci 🛰️

@AkaSci@fosstodon.org · 5 months ago

19 years ago on August 24, 2006, Pluto was demoted in status from Planet to Dwarf Planet, as the International Astronomical Union (IAU) formally defined the criteria for a planet.

A planet was defined as a celestial body that
(a) is in orbit around the Sun.
(b) has sufficient mass to assume hydrostatic equilibrium (nearly round) shape.
(c) has cleared the neighborhood around its orbit.

Pluto fails to meet the 3rd criterion 🙁

https://drive.google.com/file/d/1ckh-gW-oMYBbxKd8PgVyKwdMg1ywhA7h/view
https://www.iau.org/Iau/Science/What-we-do/Pluto-and-the-Developing-Landscape-of-Our-Solar-System.aspx?WebsiteKey=9e4eaea2-b0d6-4c4b-bd18-913a208b91be
#Pluto
1/n