Starship Asterisk*

by **Chris Peterson** » Sat Dec 17, 2022 11:34 pm

orin stepanek wrote: ↑Sat Dec 17, 2022 10:23 pm Third times a charm? Microsoft crashed twice on me now! :evil: Any way; here i am at Firefox/Duck Duck go! Is not old Sol a third generation star; formed from the remnants of a dead star? Well must have been a lot o debis that made the Solar system and also the planets and moons; and so the comets and asteroids are part of that Debris? That's where I got the idea of comets and asteroids being similar; I also agree with Chris that they are also different! Forgive me if I am all wet! 😇

It does take a lot of debris to make a star (the additional amount required to make the rest of a planetary system is tiny, however). Just look at the regions of star formation regularly featured in APOD images. Huge amounts of gas and dust.

by **orin stepanek** » Sat Dec 17, 2022 10:23 pm

Third times a charm? Microsoft crashed twice on me now!

Any way; here i am at Firefox/Duck Duck go! Is not old Sol a third generation star; formed from the remnants of a dead star? Well must have been a lot o debis that made the Solar system and also the planets and moons; and so the comets and asteroids are part of that Debris? That's where I got the idea of comets and asteroids being similar; I also agree with Chris that they are also different! Forgive me if I am all wet!

by **Chris Peterson** » Sat Dec 17, 2022 9:37 pm

johnnydeep wrote: ↑Sat Dec 17, 2022 8:11 pm
Chris Peterson wrote: ↑Sat Dec 17, 2022 4:36 pm
johnnydeep wrote: ↑Sat Dec 17, 2022 4:19 pm

I'm not seeing much of a distinction. Both stars and planets are still formed by gravitational collapse of matter, the result merely being different because of the amount and type of matter that is collapsing.

Also, couldn't a planet form by gravitational collapse even if there is no star formation also involved?
I don't really see any mechanism for a planet-sized body to form absent an accretion disk present around a new star.
Seems to me like it could happen, but I'll take your more well-informed word that it very likely can't.

I can't think of a mechanism where a planetary mass of dust could be held together by gravity tightly enough for fluidic mechanisms to operate. That's such a low mass it would just dissipate.

by **johnnydeep** » Sat Dec 17, 2022 8:11 pm

Chris Peterson wrote: ↑Sat Dec 17, 2022 4:36 pm
johnnydeep wrote: ↑Sat Dec 17, 2022 4:19 pm
Chris Peterson wrote: ↑Sat Dec 17, 2022 4:05 pm
A star, even a failed one that doesn't undergo fusion, is formed by the gravitational collapse of hydrogen (typically contaminated with a little dust). A planet, even one that no longer orbits a star, always forms from the dusty debris surrounding that stellar formation collapse.
I'm not seeing much of a distinction. Both stars and planets are still formed by gravitational collapse of matter, the result merely being different because of the amount and type of matter that is collapsing.

Also, couldn't a planet form by gravitational collapse even if there is no star formation also involved?
I don't really see any mechanism for a planet-sized body to form absent an accretion disk present around a new star.

Seems to me like it could happen, but I'll take your more well-informed word that it very likely can't.

by **Chris Peterson** » Sat Dec 17, 2022 4:36 pm

johnnydeep wrote: ↑Sat Dec 17, 2022 4:19 pm
Chris Peterson wrote: ↑Sat Dec 17, 2022 4:05 pm
johnnydeep wrote: ↑Fri Dec 16, 2022 11:30 pm

So is a star “nothing more” than a planet with a lot more hydrogen and helium that just happens to be undergoing nuclear fusion? :ssmile:
A star, even a failed one that doesn't undergo fusion, is formed by the gravitational collapse of hydrogen (typically contaminated with a little dust). A planet, even one that no longer orbits a star, always forms from the dusty debris surrounding that stellar formation collapse.
I'm not seeing much of a distinction. Both stars and planets are still formed by gravitational collapse of matter, the result merely being different because of the amount and type of matter that is collapsing.

Also, couldn't a planet form by gravitational collapse even if there is no star formation also involved?

I don't really see any mechanism for a planet-sized body to form absent an accretion disk present around a new star.

by **johnnydeep** » Sat Dec 17, 2022 4:19 pm

Chris Peterson wrote: ↑Sat Dec 17, 2022 4:05 pm
johnnydeep wrote: ↑Fri Dec 16, 2022 11:30 pm
orin stepanek wrote: ↑Fri Dec 16, 2022 10:45 pm
I will have no argument with that; but other than where they are formed and one is Icy; I see a huge similarity!
So is a star “nothing more” than a planet with a lot more hydrogen and helium that just happens to be undergoing nuclear fusion?
A star, even a failed one that doesn't undergo fusion, is formed by the gravitational collapse of hydrogen (typically contaminated with a little dust). A planet, even one that no longer orbits a star, always forms from the dusty debris surrounding that stellar formation collapse.

I'm not seeing much of a distinction. Both stars and planets are still formed by gravitational collapse of matter, the result merely being different because of the amount and type of matter that is collapsing.

Also, couldn't a planet form by gravitational collapse even if there is no star formation also involved?

by **Chris Peterson** » Sat Dec 17, 2022 4:05 pm

johnnydeep wrote: ↑Fri Dec 16, 2022 11:30 pm
orin stepanek wrote: ↑Fri Dec 16, 2022 10:45 pm
Chris Peterson wrote: ↑Fri Dec 16, 2022 2:32 pm

No. We generally understand asteroids and comets to have formed by different processes in different parts of the Solar System. So they are fundamentally different things. We can apparently end up with comets that mimic asteroids, and vice versa.
I will have no argument with that; but other than where they are formed and one is Icy; I see a huge similarity! :wink:
So is a star “nothing more” than a planet with a lot more hydrogen and helium that just happens to be undergoing nuclear fusion? :ssmile:

A star, even a failed one that doesn't undergo fusion, is formed by the gravitational collapse of hydrogen (typically contaminated with a little dust). A planet, even one that no longer orbits a star, always forms from the dusty debris surrounding that stellar formation collapse.

by **johnnydeep** » Sat Dec 17, 2022 3:58 pm

Ann wrote: ↑Sat Dec 17, 2022 5:16 am
johnnydeep wrote: ↑Fri Dec 16, 2022 11:30 pm
orin stepanek wrote: ↑Fri Dec 16, 2022 10:45 pm
I will have no argument with that; but other than where they are formed and one is Icy; I see a huge similarity!
So is a star “nothing more” than a planet with a lot more hydrogen and helium that just happens to be undergoing nuclear fusion?
Not fair, Johnny. You know that a star is always more massive than a planet, don't you? That's why it has internal fusion going on. Unless it's a brown dwarf. But brown dwarfs are a subset of stars and not "real" stars. Which begs the question... what do you call a region of such low-mass star formation that the most massive "bodies" being formed there are not even brown dwarfs, but super-Jupiters?

Is that a site of planet formation? Bear in mind that planets don't have to orbit stars, because we do talk about rogue planets.

Ann

Well, in one sense, all objects in space simply differ in mass, makeup, manner of formation, and current state of evolution.

by **Ann** » Sat Dec 17, 2022 5:16 am

johnnydeep wrote: ↑Fri Dec 16, 2022 11:30 pm
orin stepanek wrote: ↑Fri Dec 16, 2022 10:45 pm
Chris Peterson wrote: ↑Fri Dec 16, 2022 2:32 pm

No. We generally understand asteroids and comets to have formed by different processes in different parts of the Solar System. So they are fundamentally different things. We can apparently end up with comets that mimic asteroids, and vice versa.
I will have no argument with that; but other than where they are formed and one is Icy; I see a huge similarity!
So is a star “nothing more” than a planet with a lot more hydrogen and helium that just happens to be undergoing nuclear fusion?

Not fair, Johnny. You know that a star is always more massive than a planet, don't you?

That's why it has internal fusion going on. Unless it's a brown dwarf. But brown dwarfs are a subset of stars and not "real" stars. Which begs the question... what do you call a region of such low-mass star formation that the most massive "bodies" being formed there are not even brown dwarfs, but super-Jupiters?

Is that a site of planet formation? Bear in mind that planets don't have to orbit stars, because we do talk about rogue planets.

Ann

by **Chris Peterson** » Sat Dec 17, 2022 12:40 am

DonB312 wrote: ↑Sat Dec 17, 2022 12:19 am
Chris Peterson wrote: ↑Fri Dec 16, 2022 11:41 pm Not as photogenic, but a lot more than one! From Cloudbait in central Colorado on the evening of Dec 13.
Another interesting image from Cloudbait. :)

OT:
I just spent some time exploring your website and I think it is really well presented. A very clean design with consistent navigation throughout.

I especially enjoyed the image of you from 1978 with your period computer equipment. That was around the time I was in high school and first became introduced to computers and computer programming (one of the few things I discovered I actually have a real aptitude for). Seeing pictures of vintage computer equipment always gives me a strong since of nostalgia. :lol2: I also enjoy seeing people engaged in activities that they are passionate about.

The tech today is amazing, and I can do stuff with it that I didn't dream of back then... but got to say, it's never been as fun as it was in those early days of small computers.

by **DonB312** » Sat Dec 17, 2022 12:19 am

Chris Peterson wrote: ↑Fri Dec 16, 2022 11:41 pm Not as photogenic, but a lot more than one! From Cloudbait in central Colorado on the evening of Dec 13.

Another interesting image from Cloudbait.

OT:
I just spent some time exploring your website and I think it is really well presented. A very clean design with consistent navigation throughout.

I especially enjoyed the image of you from 1978 with your period computer equipment. That was around the time I was in high school and first became introduced to computers and computer programming (one of the few things I discovered I actually have a real aptitude for). Seeing pictures of vintage computer equipment always gives me a strong since of nostalgia.

I also enjoy seeing people engaged in activities that they are passionate about.

by **Chris Peterson** » Fri Dec 16, 2022 11:41 pm

Not as photogenic, but a lot more than one! From Cloudbait in central Colorado on the evening of Dec 13.
_

by **johnnydeep** » Fri Dec 16, 2022 11:30 pm

orin stepanek wrote: ↑Fri Dec 16, 2022 10:45 pm
Chris Peterson wrote: ↑Fri Dec 16, 2022 2:32 pm
orin stepanek wrote: ↑Fri Dec 16, 2022 2:12 pm ?? Is not a Comet nothing more than an asteroid that has a lot of ice
and usually a long-extended orbit?
No. We generally understand asteroids and comets to have formed by different processes in different parts of the Solar System. So they are fundamentally different things. We can apparently end up with comets that mimic asteroids, and vice versa.
I will have no argument with that; but other than where they are formed and one is Icy; I see a huge similarity!

So is a star “nothing more” than a planet with a lot more hydrogen and helium that just happens to be undergoing nuclear fusion?

by **orin stepanek** » Fri Dec 16, 2022 10:45 pm

Chris Peterson wrote: ↑Fri Dec 16, 2022 2:32 pm
orin stepanek wrote: ↑Fri Dec 16, 2022 2:12 pm ?? Is not a Comet nothing more than an asteroid that has a lot of ice
and usually a long-extended orbit?
No. We generally understand asteroids and comets to have formed by different processes in different parts of the Solar System. So they are fundamentally different things. We can apparently end up with comets that mimic asteroids, and vice versa.

I will have no argument with that; but other than where they are formed and one is Icy; I see a huge similarity!

by **Chris Peterson** » Fri Dec 16, 2022 2:32 pm

orin stepanek wrote: ↑Fri Dec 16, 2022 2:12 pm ?? Is not a Comet nothing more than an asteroid that has a lot of ice
and usually a long-extended orbit? :?

No. We generally understand asteroids and comets to have formed by different processes in different parts of the Solar System. So they are fundamentally different things. We can apparently end up with comets that mimic asteroids, and vice versa.

by **orin stepanek** » Fri Dec 16, 2022 2:12 pm

?? Is not a Comet nothing more than an asteroid that has a lot of ice
and usually a long-extended orbit?

Truly is an awesome photo!

Nice job; Jeff Dai

by **De58te** » Fri Dec 16, 2022 10:37 am

Speaking of incredible coincidences of returning from the Moon, Apollo 17, nearly 50 years earlier, at precisely 6:35 PM EST time today December16th, blasted off from the Moon for the previously last time.

by **Ann** » Fri Dec 16, 2022 7:33 am

The Geminid. Image Credit & Copyright: Jeff Dai (TWAN)

I have so little time today, but I must say that today's APOD is a stunning image!

To me this looks like a fading twilight image, where the rosy tints of sunset still colors the sky near the horizon. But the skies above are a saturated shade of blue. I guess the light blue patch of sky at right is illuminated by the Moon.

Stars reflected in still clear water is a stunningly beautiful sight. Note that many stars look brighter when reflected in the water, and their colors are enhanced.

But neither Mars nor the Geminid were captured by the mirror of the lake.

Ann

by **APOD Robot** » Fri Dec 16, 2022 5:05 am

The Geminid

Explanation: Returning from beyond the Moon, on December 11 the Orion spacecraft entered Earth's atmosphere at almost 11 kilometers per second. That's half the speed of the grain of dust that created this long fireball meteor when it entered the atmosphere on December 13, near the peak of the annual Geminid meteor shower. As our fair planet makes its yearly pass through the dust trail of mysterious asteroid 3200 Phaethon, the parallel tracks of all Geminid meteors appear to radiate from a point in the constellation Gemini. But the twin stars of Gemini hide just behind the trees on the left in this night skyscape from the beautiful Blue Moon Valley, Yunnan, China. Reflected in the still waters of the mountain lake, stars of the constellation Orion are rising near center. Captured before moonrise, dazzling Mars is still the brightest celestial beacon in the scene.

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