APOD: Star Size Comparison 2 (2018 Jun 12)

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Expand view Topic review: APOD: Star Size Comparison 2 (2018 Jun 12)

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by bystander » Wed Jun 20, 2018 9:12 pm

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by Ann » Wed Jun 20, 2018 7:28 pm

neufer wrote: Thu Jun 14, 2018 11:22 pm
ems57fcva wrote: Thu Jun 14, 2018 9:54 pm
I keep watching it. But I have more comments on the ending, and how it is not quite right:

- It treats the cosmic microwave background as being the outer boundary of the universe, when it truth it is close to the center of the universe. (I consider the "Big Bang" to be the center of the universe. Note that it is offset from us in time just the same way that the center of the Earth is offset from its surface by depth.
The cosmic microwave background is very near the outer boundary of the known universe;
while the "Big Bang" lies just outside the CMBR.


(I, personally, am at the center of the known universe :!: )
You are, of course, at the center of your own personal universe.

Like us all.

Ann

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by Chris Peterson » Wed Jun 20, 2018 5:27 pm

Winky Wink wrote: Wed Jun 20, 2018 4:46 pm
cbarnbau@valdosta.edu wrote: Tue Jun 19, 2018 2:42 pm The entire last quarter of the video is nonsense, giving the viewer the
idea that 1) the universe is round, 2) that there are other universes scattered around as there are stars in our own galaxy, 3) the cosmic
background presentation is presented as the border of our universe.
O.K. but for all you and I know 1) the universe is round spherical, 2) there are other universes scattered around as there are stars in our own galaxy (perhaps in super-duper galaxies in the super-duper universe, 3) the cosmic background plasma remnant from the BB is the border of our universe. These ideas may or not be wrong (and we'll likely never know) but that's beside the point. The point is that the video should have ended before the point of pure conjecture.
In fact, we know beyond reasonable doubt, that the Universe is not spherical (because it is not a 3D structure), and that the CMB does not define a border to the Universe. These ideas are wrong, and we pretty much know that.

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by Winky Wink » Wed Jun 20, 2018 4:46 pm

cbarnbau@valdosta.edu wrote: Tue Jun 19, 2018 2:42 pm The entire last quarter of the video is nonsense, giving the viewer the
idea that 1) the universe is round, 2) that there are other universes scattered around as there are stars in our own galaxy, 3) the cosmic
background presentation is presented as the border of our universe.
O.K. but for all you and I know 1) the universe is round spherical, 2) there are other universes scattered around as there are stars in our own galaxy (perhaps in super-duper galaxies in the super-duper universe, 3) the cosmic background plasma remnant from the BB is the border of our universe. These ideas may or not be wrong (and we'll likely never know) but that's beside the point. The point is that the video should have ended before the point of pure conjecture.

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by cbarnbau@valdosta.edu » Tue Jun 19, 2018 2:42 pm

APOD asked to point out "slight" inacurraacies. Slight? The entire last quarter of the video is nonsense, giving the viewer the
idea that 1) the universe is round, 2) that there are other universes scattered around as there are stars in our own galaxy, 3) the cosmic
background presentation is presented as the border of our universe.

APOD should not have let this video on their site.

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by ems57fcva » Tue Jun 19, 2018 3:20 am

neufer wrote: Thu Jun 14, 2018 11:22 pm
ems57fcva wrote: Thu Jun 14, 2018 9:54 pm
I keep watching it. But I have more comments on the ending, and how it is not quite right:

- It treats the cosmic microwave background as being the outer boundary of the universe, when it truth it is close to the center of the universe. (I consider the "Big Bang" to be the center of the universe. Note that it is offset from us in time just the same way that the center of the Earth is offset from its surface by depth.
The cosmic microwave background is very near the outer boundary of the known universe;
while the "Big Bang" lies just outside the CMBR.


(I, personally, am at the center of the known universe :!: )
You are spatially (in 3 dimensions) at the center of the universe just the same as you at at the center of the surface of the Earth. Under general relativity the universe is a dynamic glome whose circumference is a function of coordinate time from and with respect to the Big Bang; with the circumference of the universe being zero at the Big Bang event. As the size of a sphere is a function of the distance from its center, that is why I (analogously) say that Big Bang is the center of the universe. Or to put it yet another way: I am talking spacetime and not just space.

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by Chris Peterson » Fri Jun 15, 2018 12:40 pm

neufer wrote: Fri Jun 15, 2018 11:59 am
Chris Peterson wrote: Thu Jun 14, 2018 11:32 pm
Sort of, but really not. That's how we end up with misleading images like in the video, of some spherical CMB surface at the outer edge of the [observable] universe. The CMB isn't a structure like galaxies. It's just a soup of photons that permeates the Universe. At any given location, those photons were produced about 13.7 billion years ago.

We could travel through space and get closer to other galaxies, rather like the video shows. No matter how much we travel, though, we can never get closer to the CMB.
The current CMB is the plasma baby picture of a (45 Gly) distant structure (of the known universe) that is still out there in its evolved form and that could have been visited or viewed in the distant future if it weren't for dark energy expansion. There is absolutely nothing wrong with using the CMB baby picture to represent the distant structure itself until we have a sophisticated enough computer (Deep Thought?) to show us what it would actually look like today.
The fact remains, this presentation is confusing. It gives the impression you could zoom out and see something like this. You could not. It's also confusing because the entire video is showing us what we could actually see with our eyes, and then the view silently and magically shifts to microwaves at the end. The final frames show something completely different from what the rest show.

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by neufer » Fri Jun 15, 2018 11:59 am

Chris Peterson wrote: Thu Jun 14, 2018 11:32 pm
neufer wrote: Thu Jun 14, 2018 11:22 pm
ems57fcva wrote: Thu Jun 14, 2018 9:54 pm
I keep watching it. But I have more comments on the ending, and how it is not quite right:

- It treats the cosmic microwave background as being the outer boundary of the universe, when it truth it is close to the center of the universe. (I consider the "Big Bang" to be the center of the universe. Note that it is offset from us in time just the same way that the center of the Earth is offset from its surface by depth.
The cosmic microwave background is very near the outer boundary of the known universe;
while the "Big Bang" lies just outside the CMBR.
Sort of, but really not. That's how we end up with misleading images like in the video, of some spherical CMB surface at the outer edge of the [observable] universe. The CMB isn't a structure like galaxies. It's just a soup of photons that permeates the Universe. At any given location, those photons were produced about 13.7 billion years ago.

We could travel through space and get closer to other galaxies, rather like the video shows. No matter how much we travel, though, we can never get closer to the CMB.
The current CMB is the plasma baby picture of a (45 Gly) distant structure (of the known universe) that is still out there in its evolved form and that could have been visited or viewed in the distant future if it weren't for dark energy expansion. There is absolutely nothing wrong with using the CMB baby picture to represent the distant structure itself until we have a sophisticated enough computer (Deep Thought?) to show us what it would actually look like today.

The hot plasma CMB itself exists only in the past and would require a time machine to visit.

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by Chris Peterson » Thu Jun 14, 2018 11:32 pm

neufer wrote: Thu Jun 14, 2018 11:22 pm
ems57fcva wrote: Thu Jun 14, 2018 9:54 pm
I keep watching it. But I have more comments on the ending, and how it is not quite right:

- It treats the cosmic microwave background as being the outer boundary of the universe, when it truth it is close to the center of the universe. (I consider the "Big Bang" to be the center of the universe. Note that it is offset from us in time just the same way that the center of the Earth is offset from its surface by depth.
The cosmic microwave background is very near the outer boundary of the known universe;
while the "Big Bang" lies just outside the CMBR.
Sort of, but really not. That's how we end up with misleading images like in the video, of some spherical CMB surface at the outer edge of the [observable] universe. The CMB isn't a structure like galaxies. It's just a soup of photons that permeates the Universe. At any given location, those photons were produced about 13.7 billion years ago.

We could travel through space and get closer to other galaxies, rather like the video shows. No matter how much we travel, though, we can never get closer to the CMB.

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by neufer » Thu Jun 14, 2018 11:22 pm

ems57fcva wrote: Thu Jun 14, 2018 9:54 pm
I keep watching it. But I have more comments on the ending, and how it is not quite right:

- It treats the cosmic microwave background as being the outer boundary of the universe, when it truth it is close to the center of the universe. (I consider the "Big Bang" to be the center of the universe. Note that it is offset from us in time just the same way that the center of the Earth is offset from its surface by depth.
The cosmic microwave background is very near the outer boundary of the known universe;
while the "Big Bang" lies just outside the CMBR.


(I, personally, am at the center of the known universe :!: )

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by ems57fcva » Thu Jun 14, 2018 9:54 pm

I keep watching it. But I have more comments on the ending, and how it is not quite right:
- It treats the universe as being 90 billion light years in diameter. However, that is just the extent of the observable universe. The full extent of the universe (at this time) is unknown and must be much bigger.
- It treats the comsic microwave background as being the outer boundary of the universe, when it truth it is close to the center of the universe. (I consider the "Big Bang" to be the center of the universe. Note that it is offset from us in time just the same way that the center of the Earth is offset from its surface by depth.)
- It treats other universes as being disconnected from ours in a bigger space, when in truth other universes would be separated from ours in alternate dimensions in a hyper-spacetime. After all, the universe by definition is the full 4-dimensional spacetime continuum that we can be connected to through any kind of spacetime path (including spacelike paths which would even connect us to parts of the universe that are physically inaccessible to us).

It's still a fine video, and it may be that introducing people to the concept of a multiverse is worthwhile. But the creator still bit off more than he knew how to chew with the multiverse business.

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by Ann » Wed Jun 13, 2018 6:54 pm

Michael C wrote: Wed Jun 13, 2018 4:30 pm Seems highly unlikely that stars such as Aldebaran and UY Scuti would have the large-scale lumpy texture as depicted in the video. Do large stars have such low surface gravity that these gigantic lumps can form? Or some really weird distribution of mass that produces odd-looking equipotential surfaces? I get artistic license and all, but the physics just doesn't make sense.

Here is a picture of Betelgeuse that shows it to be lumpy, or at least irregularly shaped.

Red giants like Aldebaran, let alone red supergiants like Betelgeuse, have very hot and energetic cores and lumpy, bloated exteriors. That combination sounds like a good way to get irregular stars, particularly if the cores are "pumping irregularly", which I think is the case for red giants.

Ann

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by neufer » Wed Jun 13, 2018 5:01 pm

Michael C wrote: Wed Jun 13, 2018 4:30 pm
Seems highly unlikely that stars such as Aldebaran and UY Scuti would have the large-scale lumpy texture as depicted in the video. Do large stars have such low surface gravity that these gigantic lumps can form? Or some really weird distribution of mass that produces odd-looking equipotential surfaces? I get artistic license and all, but the physics just doesn't make sense.
The sun's photosphere is sunspot lumpy and the sun's corona is highly irregular.

Why wouldn't Aldebaran and UY Scuti have the large-scale lumpy texture as depicted in the video?

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by neufer » Wed Jun 13, 2018 4:50 pm

swank wrote: Wed Jun 13, 2018 4:21 pm
neufer wrote: Wed Jun 13, 2018 12:41 am
I Love Lucy, Queen for a Day, Beat the Clock and Dollar a Second
You really dated yourself there
My 5th grade teacher was a contestant on Queen for a Day but Dollar a Second was my favorite show.

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by Michael C » Wed Jun 13, 2018 4:30 pm

Seems highly unlikely that stars such as Aldebaran and UY Scuti would have the large-scale lumpy texture as depicted in the video. Do large stars have such low surface gravity that these gigantic lumps can form? Or some really weird distribution of mass that produces odd-looking equipotential surfaces? I get artistic license and all, but the physics just doesn't make sense.

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by swank » Wed Jun 13, 2018 4:21 pm

neufer wrote: Wed Jun 13, 2018 12:41 am I Love Lucy, Queen for a Day, Beat the Clock and Dollar a Second
You really dated yourself there

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by Apparatguy » Wed Jun 13, 2018 4:05 am

I liked the video a lot, thank you. I also liked the multiverse ending. One suggestion, to improve the multiverse sequence, is to have other universes represented by odd, dynamic shapes with odd, dynamic connections between them. Explorers, geographic and scientific, seem to find new things which are stranger than what they expected. So if there is a multiverse, anticipating it with artistic license may be appropriate. Malcolm Lambert.

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by Boomer12k » Wed Jun 13, 2018 1:15 am

I did a slide show, and a presentation, on "possible life in the galaxy" back in 73 or early 74, for Science Lab class,... If there are 200 billion stars, and only SOME had planets...then what was the possibilities for life... i took 1 percent as having planets,... and 1 percent, and 1 percent, etc... and still had around 20,000 planets....
This video says NEARLY ALL Star Systems have at least one planet.... I think my estimate just became BIGGER....

Good video... a little weird...but good...mainstream science, seems to always be behind. I was into "Multiverse" in the 80's....

:---[===] *

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by neufer » Wed Jun 13, 2018 12:41 am

Guest wrote: Tue Jun 12, 2018 11:48 pm
But seriously, would our Earth ever get noticed, amongst such giant-sized exo-planets?
Only among extraterrestrial sadomasochists who enjoy watching:
I Love Lucy, Queen for a Day, Beat the Clock and Dollar a Second

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by APOD every night » Wed Jun 13, 2018 12:28 am

Amazing, inspiring, uplifting, still gets me in a good mood every time I watch it, but there's a bit of extra imagination needed to correct a visual flaw near the end: while all the planets and stars are realistic renditions, what's the layman to think of the CMB scattering surface meant to depict our universe seen from outside, near the end? That it's mottled red-orange and blue? Anyone not familiar with cosmology would ask how that's possible when the scenes just before were whitish galaxies, and require 5 minutes of explanation when everything until then was immediately understandable.

The multiverse is very cute. You just can't stop the video with just our universe dangling in there in its garish colors, and it clearly states that we're entering pure speculation at that point; you wonder what's between the universes, though (water?) And wasn't there one like that in the first Men in Black?

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by Dr.T » Wed Jun 13, 2018 12:27 am

How about including a red dwarf? They are by far the most common star.

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by Guest » Tue Jun 12, 2018 11:48 pm

I was amazed by the "Star Size Comparison 2" video! The one thing that came to my mind was that:
if the Earth is so small, would anyone else on a giant sized planet ever know we are here?
Also, would a giant sun have planets with equally giant-sized humanoid lifeforms, on it.
(Like that old TV series, "Land of the Giants", from circa 1970's).
But seriously, would our Earth ever get noticed, amongst such giant-sized exo-planets?

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by neufer » Tue Jun 12, 2018 9:00 pm

https://en.wikipedia.org/wiki/History_of_geography wrote: <<Thales of Miletus is one of the first known philosophers known to have wondered about the shape of the world. He proposed that the world was based on water, and that all things grew out of it. He also laid down many of the astronomical and mathematical rules that would allow geography to be studied scientifically.

According to the geographer Eratosthenes, Anaximander was the first to publish a map of the [known] world. Anaximander's innovation was to represent the entire inhabited land known to the ancient Greeks. Surely aware of the sea's convexity, he may have designed his map on a slightly rounded metal surface. The centre or “navel” of the world (ὀμφαλός γῆς omphalós gẽs) could have been Delphi, but is more likely in Anaximander's time to have been located near Miletus. The Aegean Sea was near the map's centre and enclosed by three continents, themselves located in the middle of the ocean and isolated like islands by sea and rivers. Europe was bordered on the south by the Mediterranean Sea and was separated from Asia by the Black Sea, the Lake Maeotis, and, further east, either by the Phasis River (now called the Rioni) or the Tanais. The Nile flowed south into the ocean, separating Libya (which was the name for the part of the then-known African continent) from Asia.

Hecataeus of Miletus (Greek: Ἑκαταῖος ὁ Μιλήσιος; c. 550 BC – c. 476 BC) initiated a different form of geography, avoiding the mathematical calculations of Thales and Anaximander he learnt about the world by gathering previous works and speaking to the sailors who came through the busy port of Miletus. From these accounts he wrote a detailed prose account of what was known of the world.>>

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by ems57fcva » Tue Jun 12, 2018 8:03 pm

G Wolf wrote: Tue Jun 12, 2018 6:16 pm Thank you for posting that APOD Team.

This video is a nice addition to the various astronomical size comparison videos I've seen over the years. The addition of the solar system objects direct size comparison is a nice addition. It's the first time I've seen an asteroid included. The only thing I'd add would be Sedna or something else from the Kuyper Belt. Being an English major the only error I noticed was a grammar one. Instead of saying "there are many millions planets" I would have put "there are untold millions of planets." Or was it stars...?
Pluto appears just to the left of the Moon at the start. I fail to see how that does not fulfill your wish to have something from the Kuiper Belt present. And being the largest (known) Kuiper Belt object, that makes it all the more appropriate. Also note that Ceres, the largest member of the asteroid belt, is just to the left of Pluto.

Re: APOD: Star Size Comparison 2 (2018 Jun 12)

by DrJoeS » Tue Jun 12, 2018 7:26 pm

Great video. Enjoyed it all. I cannot comprehend the vastness of space and this make me less likely to. :shock:

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