Talk:Dwarf planet: Difference between revisions

For the discussion on developing a strategy for naming dwarf planet articles, please see Talk:Dwarf planet/Naming

704 Interamnia

An abstract of a new paper analyzing SPHERE data was posted on ARVIX here [1]. While its title states that Interamnia is a transistional object between a dwarf planet and an irregularly shaped body, the text of the abstract itself seems to state that Interamnia is in hydrostatic equilibrium, which therefore would make it a dwarf planet. Specifically it states, "Our observations reveal a shape that can be well approximated by an ellipsoid, and that is compatible with a fluid hydrostatic equilibrium at the 2 σ level. The rather regular shape of Interamnia implies that the size and mass limit, under which the shapes of minor bodies with a high amount of water ice in the subsurface become irregular, has to be searched among smaller (D ≲ 300km) less massive (m ≲ 3x1019 kg) bodies."XavierGreen (talk) 22:30, 3 December 2019 (UTC)

Their constructed image sure looks irregular. Could be a case like Phoebe. But is it really rotating fast enough to be scalene? — kwami (talk) 09:22, 19 December 2019 (UTC)

There are images of other angles in the journal article that look way more spherical than the one chosen for the infobox image, it may be that there is a big crater with a central peak like on Vesta. No way to know for sure until clearer images come out.XavierGreen (talk) 22:22, 30 December 2019 (UTC)

if Venus isn't a planet ...

If the sources recently added to List of Solar System objects by size hold up, and Venus, Mars and Mercury are not planets by the IAU requirement for HE, is that requirement tenable? There's no way that astronomers are going to accept the other terrestrial planets being demoted to a Small Solar System Bodies. Unless they just ignore it, the IAU would be required to modify the HE requirement, which would affect DPs as well. How close to HE would they need to be, and how could we possibly determine that for TNOs without measurements from an orbiter, even for Pluto? At that point the definition is even more obviously impractical, and there is no effective difference between "dwarf planet" and "planetoid". We might as well go with Stern's definition and call them 'DP' if like Stern we accept them as planets and 'planetoid' if like Brown we don't. — kwami (talk) 21:34, 21 December 2019 (UTC)

I highly doubt that they do. I haven't been able to access the reference being used for Venus (and Mercury) but I am disinclined to trust a paper published in 1984 that has only 3 reference and 6 citations. The Gudkova reference was a presentation at the European Planetary Science Congress in 2008, that is not peer-reviewed and thus not suitable for a wikipedia reference and I've removed it at List of Solar System Objects. The Perry reference and the book reference for Mercury both seem to be talking about rather small deviations from hydrostatic equilibrium. Physdragon (talk) 22:00, 21 December 2019 (UTC)

Yeah, we should be able to find corroborative sources if they're correct.

A possibly similar 1977 paper on Venus is available here. — kwami (talk) 23:09, 21 December 2019 (UTC)

Featured article?

This article no longer meets the featured article criteria. There are unsourced statements, statements ascribed to sources that do not support the statement and material that has been tagged for attribution since October 2017. DrKay (talk) 09:49, 25 December 2019 (UTC)

If one is interested in the surface gravity of spherical planets and dwarf planets

To make a quick estimate of the surface gravity in meters per second squared, multiply the radius in Kilometers by the density in kilograms per cubic meter, and then divide by 3,582,688. The 3,582,688 is the product of a Radius X Density that will give almost exactly 1.0 m/sec^2 surface gravity. Some Planets will have slightly higher surface gravity, a few will be slightly lower, and the Gas Giants will have slightly lower surface gravity (top of the clouds ). For example: Earth's Volumetric mean radius is about 6371.008 km, and its density is between 5514, and 5515. The GPS Gravity is taken as 9.80665 m/s^2. So 9.80665 X 3582688 = 35,134,167.28. Then divide by the radius of 6371.008 to get a non rounded density of 5514.695 206. Now you can round to 5514.7 kg/m^3. This is between the 5514 that NASA currently uses, and the 5515 they used previously.

You can estimate the surface gravity of every Planet, Dwarf Planet, Moon, or any other spherical, or semi-spherical object by: Radius X Density / 3,582,688 = __________ m/s^2. 98.245.216.62 (talk) 20:55, 23 October 2020 (UTC)

Removed text

I removed the following:

In 2012, Stern stated that there are more than a dozen known dwarf planets.

I should've removed this years ago, but was waiting for a better ref and forgot about it. The reason is that Stern was counting satellite planets as dwarf planets (p.c. 2012). So the quantity "dozen" here doesn't tell us anything about how many TNOs Stern considered to be DPs. — kwami (talk) 09:05, 15 February 2021 (UTC)

Featured article status

This is an old FA promotion, and does not seem to have kept up over the succeeding decade. There are a couple of unsourced paragraphs and other unsourced text, and the prose in many areas has short paragraphs and small sections. Some areas appear not to have received a comprehensive update since early FA. The History of the Concept section is mostly based on 2006/2008 sources, many of which are news or magazine articles rather than higher quality sources which are certainly available. Updates since then are restricted to a brief couple of sentences, which seems insufficient (and is partially sourced to twitter). The Exploration section is paltry, it is where I would expect to find for example an explanation of the reasoning that led to the sentence "Ceres is close to equilibrium, but some gravitational anomalies remain unexplained", which is cited to a Dawn paper. The overall structure of the article has some oddities, why is "Contention regarding the reclassification of Pluto" a separate section so far away from the History of the concept section? The pie charts are causing some image sandwiching, and seem a really odd way to present that data. The source formatting needs some tightening: there's a bare url, and others lack page numbers and access-dates. Others may find more missing areas, it does feel an oddly short article for the scope involved. CMD (talk) 03:52, 14 August 2021 (UTC)