Articles

6. Milky Way Galaxy Introduction


Welcome back to OpenSpace. This is
Carter. I’m going to lead you through a little bit of a tour of the Milky Way
Galaxy, thanks to the Digital Universe 3D Atlas datasets. Digital Universe
contains the datasets for the Milky Way from various astronomical catalogs,
brought together into one, and also the extra galactic or galaxy surveys beyond
the Milky Way. So OpenSpace comes up. Once again, with my left mouse, I move
around Earth, the daily image, and also defaulted to on are the
paths or the trails of the planets. Let me move around here and see the Sun. So
what we see is the Sun of course in our sky, and it moves through the same patch
of sky — based on the sense that we go around the Sun, we go around in a plane
which we call the ecliptic plane, and in order to illustrate the motion, what I
can do is let me just speed the Earth up. We start to see the Earth rotate. And if
I rotate fast enough, we can see the other planets are moving. But we can
also see the Sun is moving. And if I let this continue, and the Sun
will move out of the view. So what I’m gonna do is, as we do this,
I’ll move these menus around, I’m going to open up the Milky Way datasets. And
the first one are constellations. And what I’m going to do is open up the
constellations subdirectory and enable the constellations. And what now I see
are the point-to-point connections, the stellar positions that show the
constellations. And – oops I just turned it off by mistake — let me turn that back on, whoa
I hit the transparency. Oh that’s good to actually — by mistake, I hit the
transparency button, but that allows you to see this is a slider, I hit the
transparency slider. So we can make them dominant or not, but
as we see, just hovering above the Earth, rotating quickly, is that we see the Sun
and the other planets all move through this section of sky. And through these 12
red highlighted constellations. And 12, because that’s one for each month.
So there’s a diagonal constellations that we see the Sun move
through. So that just sets us up in a way, that if we begin to move out — what I want
to do is I’m gonna pause time. I can pause time either over here and hit
pause, or I go slower, but I could also hit the spacebar that will stop time. So
stopped time, and we will now move away from the Earth-Moon system. Once again,
the right mouse, holding that down allows me to move out into the solar system. And
so as I do we can see the distant glow of the Sun. Now of course the Sun
would dominate and so it would be the brightest thing we see, but we now see
the backdrop of constellations. One thing I’d like to do, to show you an advanced
feature which can be of use, is I’m going to hit the F3 key, which brings up our
advanced menu, which I had my time controls next to. And I’m gonna come down
to the fourth entry — it says global properties. And if I turn that on, pops up
a submenu, and there are many different things to explore here. But the first
thing I thought I would do is just come down to this set of sliders under
render engine. Open that and amongst various things there’s a background exposure. That’s the third slider down. And I usually
drag that up to about 4. And when I do, this is going to enhance the background
for us and that’s what we want to see. And then I can kind of get rid of this
submenu. And so now we’re seeing the solar system, the Sun, the reds of diagonal
constellations, as we move out. And as we move out, we might want to see the star labels, so that we can see what stars we’re
actually seeing. So to do that, I’ll open up the stars menu and there are stars
labels. I’ll command enable them and we can now see star labels. So in this case,
you see some star labels are large and some are small, and you might say, ‘Well
why is that?’ If I point out this beautiful
constellation of the scorpion right here, Scorpius, and it’s right next to the
brightest section of the Milky Way, is the prominent star Antares. This
kind of got some small typeface, then there’s a star with a larger typeface.
Maybe you’ve heard of, or not, but Java. And then there’s Kaus Borealis and Kaus
Australis over here. Well the labels actually reflect
perspective. These are stars that are closer. So Antares is actually about 300
light years away, it’s a red giant and it’s still a prominent star, which means
it’s a very bright star, quite far away. But we’re seeing these star labels
because they are giving us an early indication of distance. So let’s now move
away from our solar system. I’m only 11 lightdays away from the Sun. I got to
move away from the Sun with my right mouse button, and when I get out here —
there — at one lightyear, we now pop on the Sun’s glare, as if it’s just another
star. And it’s the brightest thing we see because we’re close to it. At this point,
we’ve moved far enough away to where I see Proxima Centauri. So okay I can still
use the left mouse button to move around and we can now see the red zodiacal
constellations. And we can see the Proxima has already moved away from its
location sort of on the wallpaper of sky, if you will, and we might be able to move
down — there’s the Southern Cross. I’m moving in this direction because I expect to
see soon the star Sirius which is eight and a half lightyears away. And Procyon,
eleven lightyears away. So those are also close, so
if I move about we will see it also drags the line, to show the constellation
connection, but we can see that those stars are pretty close. If I come down
here, here’s Orion, it’s laying on its side. If I want to turn it up, I just
depress the middle mouse button, and that allows me to bring Orion, so Orion looks
like he’s standing up. Also you’ll notice some of the constellation lines might be
shimmering, maybe flashing on and off — we’re working on that.
So in this early version, I’m not sure if we’ll get that fixed or not, but that’s
okay for now. And also perhaps the star labels are too large. So bring up your
menu, I have my stars open under my Milky Way category, I have my star labels,
and if we come down, I can adjust the text maximum size. And I’m going to
minimize that. So that has the effect of drawing these labels even smaller, so
that they’re not so dominant on the screen. But now we can see how the constellation
lines will follow this perspective. If I move out even farther —
oh boy — we now see how the constellations all become these lines. It makes sense
from the Earth but here they kind of point in perspective to where
the Sun is. Well that gets rather confusing, so I usually at this point
like to come up, turn the constellations off. So I I turn their enabling off.
And now I see the stars that we know and love in the labels here. So this is our
near field of stars. We’re seeing them for what they are. If they’re not bright
enough, you say you want to see more stars, I can do that. Just open up my stars
category, and grab the scale factor slider, and I can brighten that up. So the stars are more prominent out here,
and so we see that. And you kind of say, ‘well, okay what does this mean?’ What I’d
like to do is give us something that perhaps we can appreciate within
our reach out into space. So what I’m going to do now is bring up underneath
others/grids, I can bring up the equatorial sphere, and I enable it. So I
open it up and there it is. If I don’t like its color, it’s a little too blue, I
can come down click on the color swatch and I could brighten it up a little bit,
like so. That’s fine, I changed its color. Also if I don’t like a double line width,
I come come down, and I kind of like a single line width, let me get that down to.
And so what this sphere represents is stretching the Earth’s latitude and
longitude out into space. In this case, the center is the Sun.
Down here as we see a tiny little label, says Sun. That’s at the center. And up
here is aligned to the North celestial pole and the South celestial Pole, but
what’s most important is we’ve given this a radius. And the radius is 75
lightyears. This represents how far our radio waves have traveled since the
Earth became radio-bright around the birth of radar and television carrier
waves. It’s basically around the time of World War II. So out here is how far our
radio signals have reached, which means that these stars that are labeled — the
ones that we see within the sphere. And actually if we wanted, just another word
to the wise, is if you stop everything seems to flatten out. To continue with a
sort of a three-dimensional feel, all you got to do is go rotate the camera a
little bit. If you hit the F key, that enables us to just keep moving.
And so in that way, now we can kind of tell what’s
close and what’s far. So everything within the spirit has heard from us;
everything outside of the sphere has yet to hear from us. Well what else is in
this near field of stars? We’ve been discovering exoplanets.
Open this up, the dynamically discovered exoplanets that we now see are here.
In other words, these labels indicate star positions where there are stars that that are host to
planets. If we want to see their labels, we should be able to come down and turn
their labels on as well. Oh boy — and they’re too big. And so if
they’re too big, grab their scale factor here — or actually, no — scale factor would
be the size of the light of the target. If we come down here, the text
maximum size, we want to make smaller and then in that way, we can make the labels
small. Now this is an example what I consider a bad map — there’s too much
information on here. Unless you want to read the individual labels, come up here,
I’m just gonna turn those labels back off, and we’re just showing where the exoplanets are.
So now if I pull out in this broader perspective, we can see that this
radio sphere, 75 light-years in radius — a tremendous distance, but we’re moving out
into the Milky Way Galaxy, and that we will see that, in fact, this is actually
pretty small. It’s a very small portion of the Milky Way Galaxy.The Milky Way Galaxy
is a big flat barred spiral galaxy that its diameter is about a 100,000
lightyears. This is really just 150 lightyears in diameter — once again, 75 lightyears in radius. I’m going to turn off the dynamical
exoplanets — just going to collapse the exoplanets down, and I want
move in a little closer. If I move around the outside of the radiosphere,
with the beautiful bright section of the Milky Way, that corresponds to
Scorpio, Sagittarius region, and we see that in view, that means that we’re
moving out into the opposite side of the sky that we think of. And now in the
northern hemisphere, that bright section of the Milky Way, we think of as summer.
If you were in Australia, it would be winter. But for the seasonality in
northern hemisphere we think of this beautiful bright section of the Milky
Way that we see in the summer. So if I’m moving away from the Sun to the opposite
side of the sky, I’m moving into the constellations that we consider the
winter constellations. And as I do that, we will find the Hyades star cluster. And
it’s a 150 light years away. The Hyades are what we associate with the face of
Taurus the Bull. In fact, it’s kind of a V shape of stars, as we see here. And
we’re seeing it from the opposite side. But this is really the nearest
well-defined star cluster to us, 150 lightyears away. So it’s twice a
distance of the edge of the radius here. In fact, from Earth we see this V shape
of stars crowned by a prominent red star that we know of as Aldebaran. And
Aldebaran is right here. And if I come close to Aldebaran, we can see that it is
just about on the edge of the radiosphere. Aldebaran is just hearing the
early signals from Earth corresponding around the time of World War II. If I
continue moving out, I should encounter the heart of Taurus the Bull, another
star cluster, very well known, as the Pleiades. And here we see the Pleiades.
They are even farther away — they’re at 400 lightyears away.
If you had a really good telescope, and you were orbiting say one of these
stars out here, and you looked back to Earth, you’d see the Earth 400 years ago.
What happened on Earth 400 years ago — there was a gray-haired guy with a beard
with the first telescope looking at the sky — Galileo. So if you’re out here you’d
see the Earth 400 years ago, the time Galileo was looking back at you. So I’m
talking about these star clusters. This is useful for us to see basically to
begin to understand the galaxy in terms of different types of data. So let’s
consider these star clusters as categories. First thing I’m gonna do is
now the star names are sort of, you know, we’ve seen them, and we’re
gonna turn those labels off. Star labels, turn them off. So now we just see the
radiosphere. The Hyades cluster that I talked about is down here, but that’ll be
emphasized if I turn on those star cluster categories. We call them open clusters —
they’re also called galactic clusters. I turn on these things and now
we see, ‘Oh wow,’ the screen fills up with a whole bunch of dots. If they’re too big,
I can scale them down a bit. So I’m gonna scale them — there’s the scale factor scale
slider — and we can now see: there’s the Hyades, there’s the Pleiades. We can also
see that as a category, if I just move about, that they tend to be contained
close to the Milky Way. So open clusters, meaning that they’re kind of loose
clusters. We see much tighter clusters, and we call them globular clusters.
I also mentioned that we call these open clusters ‘galactic clusters’ because they
are constrained pretty much to the Milky Way band. I’m now going to turn on the
globular star clusters — they tend to be farther away. And I’m just gonna come up
here, globular clusters, open up this category. And I will enable it. And we get these yellow pentagons. Now okay, they also seem a little large, so what I’m gonna do is I’m gonna grab their
scale factor, I’m gonna make them a little smaller. Now notice how you see
many yellow pentagons in this direction, but if I look
away, I hardly see any. This was noticed by astronomers, that these
different types of star clusters, and especially these globular star clusters,
tended to cluster around the brightest section of the Milky Way. Well this has a
story to tell us. Let’s move out farther away to gain a broader
perspective. Now we can see how the globular clusters really exist toward
that bright section of the Milky Way, and now from this distant view, we can see how
the open or galactic clusters really are constrained pretty much into a plane —
we don’t see too many up here, or down here, but we see a lots of them along
this plane. I’m gonna bring up another dataset to show you where stars are
born. This is where we typically see like a nebula, like the Orion Nebula or Lagoon
Nebula, where stars are being born. And we can look at these typically tracked in
radio light, but we can now see where these stellar birth regions are, in
blue — these blue hexagons. And with this, this traces out a much broader census of
the Milky Way galaxy. And if I move out far enough, we will see our image our
stand-in for us, it’s NGC 1230 — it’s not our Milky Way Galaxy, but since we’re
inside our Milky Way Galaxy, we use another galaxy, which we know to be kind
of similar to the Milky Way as our stand-in, as our proxy. So with that, we
have moved out from the Earth, seeing the organization of our
solar system and the constellations that surround us. And then the exoplanets
that are in close to us, our radiosphere, and now we’ve moved out so far that
we can see now with these tales of two different types of star clusters, and
then the stellar birth regions that we can see within this data. The data gives
us this view of the Milky Way. If I wanted to make this image of our stand-in,
the Milky Way, a little dimmer, I can do that. Its image, actually we put
that into the universe category, under galaxies. So once again, I want to dim
this image of our galaxy, and you go up to Milky Way Galaxy image, and it’s
enabled. I can turn it on and off. Let’s say I want to leave it on and I just
want to bring its transparency down — I can do that. Once again, let’s just move
slowly in toward the Earth. As we do, the galaxy image — we’re doing a
transition between it and the backdrop that we see of the Milky Way Band. Now
let’s just come closer and closer and just searching for our tiny radiosphere
in the Milky Way Galaxy, of which we’re in the center. Remember I brighten the
stars for us to see, once again, the Hyades star cluster. We’re coming in
closer to it, 150 lightyears. The red star Aldebaran, we’re at 75
lightyears and now, coming back to a dim little star that we call the Sun, our
home. If I really push fast, that’s gonna go — it toggles away at about a lightyear
out. Now we’re coming into the view of the trails of the solar system. And of
course the third one out has a little rocky moon orbiting us — here, the
farthest humans have ever been away. Finally coming up on this view of our
lovely Earth in context. So with that, it’s kind of a longer video here, but
gives you a sense of how to open up these menus and go through some of the
data, turn them on and off, and adjust them, scale them, brighten them, make them
more transparent — however, you will. But it gives you a sense of the Milky Way Galaxy.
Thank you.

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Comments
  • Can we use OpenSpace to take a trip to see a representation of the Super Massive Black Hole Sgr A* at the center of the Milky Way?

  • Open Space, Carter and everyone involved, I must congratulate you on such a wonderful set of tutorial videos. I have watched all 6 and I am certain to return to see them again once I have installed the project onto my MAC. I have however hit a wall on a finding an active support community or forum. Slack doesn't have a valid invite from the download page and the wiki area of links for users are not finished either. Please stay in touch , as I am sure to need guidance to get me rolling.

  • This is an amazing piece of software. Does anyone know if these settings are configurable via files or if you need to use the on-screen dialogs to change the settings?

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