
Detailed 3D map of Milky Way shows 'warped' shape - sgt101
https://www.theguardian.com/science/2019/aug/01/most-detailed-ever-3d-map-of-milky-way-shows-warped-shape-cepheid
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PopePompus
When I started grad school, one of the things my thesis adviser suggested I do
was to spend a few hours looking at the Palomar Sky Survey plates (this was in
1980). I spent many pleasant hours doing that, and what was striking was how
few perfectly symmetric spiral galaxies there are, in relative terms. You see
beautiful symmetric galaxies pictured in your Astronomy text books, but in
truth most spirals are warped, or show distortion from a nearby companion, or
obviously are merging with another galaxy, etc. Most spiral galaxies are
deformed.

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hestipod
I've developed a fascination with astrophotography, one day hope to have a
camera that can manage more than pinpoints/streaks/black noise, and while I
always liked to go look at the stars on clear nights the technical aspects of
it have reawakened the interest in space. Seeing the Milky Way across the sky
at night with the naked eye is amazing and makes it hard to forget your
smallness. You can get lost thinking stars are just pinpoints of light because
they all generally look the same, but larger masses of them and seeing
galaxies, clusters etc in binoculars etc just juices me up. Imaging that I can
SEE Jupiter but the light is taking 45min to reach me is mind-blowing. Forget
the larger distances to stars...it's inconceivable at times. Sometimes I have
gotten vertigo seeing how our Solar system is tilted and imagining us swirling
through the arm.

One thing that seems to have changed is visible satellites. Or maybe I am just
missing them. I recall as a child watching the sky with my grandfather and
you'd regularly see a "star" moving across the sky and he'd excitedly point it
out as a satellite.

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samplatt
>one day hope to have a camera that can manage more than
pinpoints/streaks/black noise

You can build an arduino-powered "barn-door tracker" for ~$40 that will
significantly help with this.
[https://www.youtube.com/watch?v=5hqXqqTtWzU](https://www.youtube.com/watch?v=5hqXqqTtWzU)

If you're hoping to hook up a DSLR to a telescope this won't help though, not
big enough. Plus, this style of tracker only tracks through one axis, limiting
exposure time to ~10seconds before stuff gets blurry & drift destroys the
image... but that's still better than the ~2seconds or so that you get without
it.

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hestipod
That's very cool thank you. I seem to recall an astronaut on the ISS making
something kind of related with parts on hand...Don Pettit I think?

*Found it: [https://science.nasa.gov/science-news/science-at-nasa/2003/2...](https://science.nasa.gov/science-news/science-at-nasa/2003/24mar_noseprints/)

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rbanffy
The sky from the planets at the outer regions far from the plane must be
astonishing.

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unnouinceput
For an astronomer that lives there, yes. For naked eye would be mostly black
sky, just like ours on edges. That's why I love our place, it shows our galaxy
beautifully stretching across.

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rbanffy
Do we have software to easily simulate that?

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aplaice
Celestia[0][1] can just about do it. In principle, it can show you what you'd
see from any point in space. In practice, it's limited by the data it has (for
stars, it uses the Hipparcos Catalogue, which only contains ~ 100,000 stars of
the ~ 250 billion that are in the Milky Way) and displays the Milky Way,
outside our "immediate" neighbourhood (i.e. several hundred light years), as
just a set of amorphous blobs. Hence you can visualise the Milky Way as seen
from the edge of the galaxy, but it'll be rather blurry. (It also obviously
doesn't include the newly discovered warped shape.)

Edit: For this purpose, I think that this "Chrome Experiment"[2], might be
better.

Also see "Gaia Sky"[3] which I haven't tried, but which looks really
interesting and may well do what you want.

[0] [https://celestia.space/](https://celestia.space/)

[1]
[https://en.wikipedia.org/wiki/Celestia](https://en.wikipedia.org/wiki/Celestia)

[2]
[https://experiments.withgoogle.com/100000-stars](https://experiments.withgoogle.com/100000-stars)

[3] [http://sci.esa.int/gaia/60036-gaia-data-release-2-virtual-
re...](http://sci.esa.int/gaia/60036-gaia-data-release-2-virtual-reality-
resources/)

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mirimir
> As with the previous work, the new study shows the Cepheids
> disproportionately lie on one side of the warped galaxy, forming an arc-
> shaped spread.

> The Polish team also found younger Cepheids lie nearer the centre of the
> Milky Way, while older Cepheids are further out. A computer simulation
> revealed there would need to have been star-forming events 64m, 113m and
> 175m years ago to produce the distribution of Cepheids seen today.

I don't get why the Cepheids are bunched. Even with the modeling video. It
shows them forming in bursts, yes. And with differential rotation, they bunch
on one side. But still, it shows the formation bursts mainly on one side.

So why?

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AnimalMuppet
I'm not an astronomer. But I _think_ that stars in galaxies are supposed to
orbit with approximately the same period, independent of distance from the
center, due to dark matter distributions.

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rook166
Almost - stars orbit with approximately the same velocity, not period.

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coldsmoke
You beat me to it while I was looking for references. =)

"The stars and gas in the Milky Way rotate about its center differentially,
meaning that the rotation period varies with location. As is typical for
spiral galaxies, the orbital speed of most stars in the Milky Way does not
depend strongly on their distance from the center. Away from the central bulge
or outer rim, the typical stellar orbital speed is between 210 ± 10 km/s
(470,000 ± 22,000 mph). Hence the orbital period of the typical star is
directly proportional only to the length of the path traveled."

[https://en.m.wikipedia.org/wiki/Milky_Way#Galactic_rotation](https://en.m.wikipedia.org/wiki/Milky_Way#Galactic_rotation)

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saagarjha
How far from the galactic plane is our Solar System?

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mikeash
Something in the neighborhood of 20 parsecs, according to:
[https://astronomy.stackexchange.com/questions/822/how-far-
is...](https://astronomy.stackexchange.com/questions/822/how-far-is-the-earth-
sun-above-below-the-galactic-plane-and-is-it-heading-towar#8336)

~~~
btilly
However this is unusual for us. We spend most of our time farther from the
plane, and just happen to be passing through at the moment.

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cl0ckt0wer
Watching that video makes me wonder why so many Cepheids spawned in the sun's
wake ~120 million years ago.

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abcanthur
Fascinator hat!?!?

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jetrink
[https://en.wikipedia.org/wiki/Fascinator](https://en.wikipedia.org/wiki/Fascinator)

~~~
mirimir
I don't get why they say "fascinator". To me, it's like my favorite old floppy
hat.

Edit: [https://m.media-
amazon.com/images/I/61IdlF0D2eL._AC_UL320_.j...](https://m.media-
amazon.com/images/I/61IdlF0D2eL._AC_UL320_.jpg)

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nobrains
Like when you see a pizza dough being spun...

