Starship Asterisk*

Iksarfighter wrote: ↑Sun Sep 11, 2022 7:00 am Could we guess Venus so slowed because it is internally liquid and has strong tidal forces from the Sun ?
Mercury must not be liquid as it is small.

Iksarfighter wrote: ↑Sun Sep 11, 2022 7:00 am Could we guess Venus so slowed because it is internally liquid and has strong tidal forces from the Sun ?
Mercury must not be liquid as it is small.

De58te wrote: ↑Sun Sep 11, 2022 1:04 pm With regard to number 1, Venus being flipped over by "the inner planets .. most certainly underwent dramatic spin-altering collisions" as stated in the description, I remember an essay by Issac Asimov where he stated, if Venus suffered a monumental collision, then what imaginably incredible stroke of luck made it settle down into the most nearly perfect circular orbit of all the planets?

Sa Ji Tario wrote: ↑Sun Sep 11, 2022 2:24 pm Not everything is said, but it occurs to me that the tidal forces of the major planets, added to those of the Sun, induced (when the Earth and Venus were still in a gaseous state and in formation) that Venus is rotating opposite with respect to the Earth for being of almost identical masses

MoonRockMan wrote: ↑Sun Sep 11, 2022 6:43 pm The way Jupiter's tilt is when spinning around its axis, would that mean that the Sun is low in the sky in the polar regions?

johnnydeep wrote: ↑Sun Sep 11, 2022 7:08 pm

MoonRockMan wrote: ↑Sun Sep 11, 2022 6:43 pm The way Jupiter's tilt is when spinning around its axis, would that mean that the Sun is low in the sky in the polar regions?

Unless this is a trick question, the answer is yes! And the same goes for Mercury and Venus. All three rotate almost perpendicularly to the plane of their orbit around the Sun.

Chris Peterson wrote: ↑Sun Sep 11, 2022 2:35 pm

Sa Ji Tario wrote: ↑Sun Sep 11, 2022 2:24 pm Not everything is said, but it occurs to me that the tidal forces of the major planets, added to those of the Sun, induced (when the Earth and Venus were still in a gaseous state and in formation) that Venus is rotating opposite with respect to the Earth for being of almost identical masses

When the planets were forming the accreting bodies that were coming together out of the orbiting accretion disk were certainly all rotating in the same direction. That of the rotating disk itself.

orin stepanek wrote: ↑Sun Sep 11, 2022 2:48 pm planets_iau.jpg
planets of our solar system & 2 dwarf planets!
Kitty's are doing research!

XgeoX wrote: ↑Tue Sep 13, 2022 10:39 am

orin stepanek wrote: ↑Sun Sep 11, 2022 2:48 pm planets_iau.jpg
planets of our solar system & 2 dwarf planets!
Kitty's are doing research!

Uh they prefer to be called “little” planets
Adorable kitties as usual, your pics always bring a smile to my face.

Eric

orin stepanek wrote: ↑Tue Sep 13, 2022 1:45 pm

XgeoX wrote: ↑Tue Sep 13, 2022 10:39 am

orin stepanek wrote: ↑Sun Sep 11, 2022 2:48 pm planets_iau.jpg
planets of our solar system & 2 dwarf planets!
Kitty's are doing research!

Uh they prefer to be called “little” planets
Adorable kitties as usual, your pics always bring a smile to my face.

Eric

I never did like that the planet status was changed! To me a planet is a planet! At least Ceres got some attention!
I get the animal photos from the dialog!

XgeoX wrote: ↑Wed Sep 14, 2022 5:34 am

orin stepanek wrote: ↑Tue Sep 13, 2022 1:45 pm

XgeoX wrote: ↑Tue Sep 13, 2022 10:39 am
Uh they prefer to be called “little” planets
Adorable kitties as usual, your pics always bring a smile to my face.

Eric

I never did like that the planet status was changed! To me a planet is a planet! At least Ceres got some attention!
I get the animal photos from the dialog!

I’m with you, I say if it’s round and not a moon it’s a planet!

Ann wrote: ↑Wed Sep 14, 2022 5:47 am

XgeoX wrote: ↑Wed Sep 14, 2022 5:34 am

orin stepanek wrote: ↑Tue Sep 13, 2022 1:45 pm

I never did like that the planet status was changed! To me a planet is a planet! At least Ceres got some attention!
I get the animal photos from the dialog!

I’m with you, I say if it’s round and not a moon it’s a planet!

Well, Ceres is round and it is not a moon, so... Welcome to planethood, Ceres!

Although I havde to admit that Pluto is a heck of a lot more impressive as a planet than Ceres is.

Ann

orin stepanek wrote: ↑Wed Sep 14, 2022 10:30 am

Ann wrote: ↑Wed Sep 14, 2022 5:47 am

XgeoX wrote: ↑Wed Sep 14, 2022 5:34 am

I’m with you, I say if it’s round and not a moon it’s a planet!

Well, Ceres is round and it is not a moon, so... Welcome to planethood, Ceres!

Although I havde to admit that Pluto is a heck of a lot more impressive as a planet than Ceres is.

Ann

Pluto is very impressive indeed! It has a lot of characteristics for future exploration!

https://en.wikipedia.org/wiki/Planetary-mass_object wrote:A planetary-mass object (PMO), planemo,[1] or planetary body is by geophysical definition of celestial objects any celestial object massive enough to achieve hydrostatic equilibrium (to be rounded under its own gravity), but not enough to sustain core fusion like a star.[2][3]

The purpose of this term is to refer to a broader range of celestial objects than the concept of planet, since many objects similar in geophysical terms do not conform to typical expectations for a planet. Planetary-mass objects can be quite distinguished in origin and location. Planetary-mass objects include dwarf planets, planetary-mass moons or free-floating planemos, which may have been ejected from a system (rogue planets) or formed through cloud-collapse rather than accretion (sometimes called sub-brown dwarfs).

johnnydeep wrote: ↑Wed Sep 14, 2022 3:02 pm

orin stepanek wrote: ↑Wed Sep 14, 2022 10:30 am

Ann wrote: ↑Wed Sep 14, 2022 5:47 am


Well, Ceres is round and it is not a moon, so... Welcome to planethood, Ceres! 😀

Although I havde to admit that Pluto is a heck of a lot more impressive as a planet than Ceres is.

Ann

Pluto is very impressive indeed! It has a lot of characteristics for future exploration!

I just consider all these things to be "Planetary Mass Objects" and leave it at that.

https://en.wikipedia.org/wiki/Planetary-mass_object wrote:A planetary-mass object (PMO), planemo,[1] or planetary body is by geophysical definition of celestial objects any celestial object massive enough to achieve hydrostatic equilibrium (to be rounded under its own gravity), but not enough to sustain core fusion like a star.[2][3]

The purpose of this term is to refer to a broader range of celestial objects than the concept of planet, since many objects similar in geophysical terms do not conform to typical expectations for a planet. Planetary-mass objects can be quite distinguished in origin and location. Planetary-mass objects include dwarf planets, planetary-mass moons or free-floating planemos, which may have been ejected from a system (rogue planets) or formed through cloud-collapse rather than accretion (sometimes called sub-brown dwarfs).

Chris Peterson wrote: ↑Wed Sep 14, 2022 3:21 pm

johnnydeep wrote: ↑Wed Sep 14, 2022 3:02 pm

orin stepanek wrote: ↑Wed Sep 14, 2022 10:30 am
Pluto is very impressive indeed! It has a lot of characteristics for future exploration!

I just consider all these things to be "Planetary Mass Objects" and leave it at that.

https://en.wikipedia.org/wiki/Planetary-mass_object wrote:A planetary-mass object (PMO), planemo,[1] or planetary body is by geophysical definition of celestial objects any celestial object massive enough to achieve hydrostatic equilibrium (to be rounded under its own gravity), but not enough to sustain core fusion like a star.[2][3]

The purpose of this term is to refer to a broader range of celestial objects than the concept of planet, since many objects similar in geophysical terms do not conform to typical expectations for a planet. Planetary-mass objects can be quite distinguished in origin and location. Planetary-mass objects include dwarf planets, planetary-mass moons or free-floating planemos, which may have been ejected from a system (rogue planets) or formed through cloud-collapse rather than accretion (sometimes called sub-brown dwarfs).

Classification is, by its nature, hierarchical. PMO represents a high-order category, with "planet" below it, and planet types (dwarf, gas, terrestrial, ice, etc) below that.

johnnydeep wrote: ↑Wed Sep 14, 2022 3:58 pm

Chris Peterson wrote: ↑Wed Sep 14, 2022 3:21 pm

johnnydeep wrote: ↑Wed Sep 14, 2022 3:02 pm

I just consider all these things to be "Planetary Mass Objects" and leave it at that.

Classification is, by its nature, hierarchical. PMO represents a high-order category, with "planet" below it, and planet types (dwarf, gas, terrestrial, ice, etc) below that.

Reading the wikipedia article on dwarf planet made my head hurt. I'd like to see a definitive hierarchical classification chart showing all the different types of solar system objects and how they relate.

Chris Peterson wrote: ↑Wed Sep 14, 2022 4:03 pm

johnnydeep wrote: ↑Wed Sep 14, 2022 3:58 pm

Chris Peterson wrote: ↑Wed Sep 14, 2022 3:21 pm
Classification is, by its nature, hierarchical. PMO represents a high-order category, with "planet" below it, and planet types (dwarf, gas, terrestrial, ice, etc) below that.

Reading the wikipedia article on dwarf planet made my head hurt. I'd like to see a definitive hierarchical classification chart showing all the different types of solar system objects and how they relate.

"Dwarf planet" as officially (IAU) described is an absurdity. How can a dwarf planet not be a planet? Logically, "dwarf" should be seen as a qualifier like "terrestrial" or "gas giant". Really silly.

Rationally, "planet" should define any body that is sufficiently massive to form a spherical shape under its own gravity and which orbits a star (or originated in orbit around a star). From there we can further classify them. That whole "clears its orbit of debris" qualification is pretty useless and pointless.