
Hubble takes gigantic image of the Triangulum Galaxy - _Microft
https://www.spacetelescope.org/news/heic1901/
======
jcims
One of the largest known stars is VY Canis Majoris. It's in the Milky Way and
has a diameter of 2 billion km. Triangulum is ~2.7m ly (2.5e19m) away. That's
an angular diameter of 2e9/2.5e19 or roughly 1e-10 radians. Imagine a star
this size in that galaxy.

A red blood cell has a diameter of ~8e-6m. Pick up a mechanical pencil sitting
around you with a .5mm lead in it. Study the tip of that pencil and imagine 60
little red platelets lined up in a row fitting across its width. Now pick up
one of those little red blood cells and stick it to a window. Then get in your
car and drive 8e-6m/1e-10 or 86km away and look back across the (flat,
obviously) Earth to that window. As Triangulum rises over the horizon on the
other side of our window, that little red blood cell would _fully eclipse_ our
remote twin of VY Canis Majoris.

I don't know if I'm seeing individual stars in that zoomable image, but if I
am I don't understand how we make optics that good. (Caveat, Hubble's
resolution is rated at ~2.4e-7 radians, so it's likely that those blobs aren't
stars, or my math is off somewhere.)

~~~
jahnu
Its worth mentioning that VY Canis Majoris has a mass of "only" 17 Solar
masses (+-8). This means it has a very low density.

"Despite the mass and very large size, VY CMa has an average density of 5.33
to 8.38 mg/m3 (0.00000533 to 0.00000838 kg/m3), it is over 100,000 times less
dense than Earth's atmosphere at sea level (1.2 kg/m3). " [0]

Often these huge but low density objects are incorrectly rendered like our Sun
with a "hard" surface. I think it's a pity because they are even weirder and
more fascinating objects than that.

[0]
[https://en.wikipedia.org/wiki/VY_Canis_Majoris](https://en.wikipedia.org/wiki/VY_Canis_Majoris)

~~~
phkahler
How is that possible? And how can that be determined? I'm both intrigued and
in disbelief. Does it not collapse due to internal pressure from fusion
reactions? Is that just heat, or radiation pressure too? Have I just answered
my own questions?

~~~
gmiller123456
It's important to note that the average density is low, it doesn't mean it's
uniformly that dense. I cannot speak for this star in particular, but a lot of
variable stars expand and contract so fast that material actually bounces off
of it sending out a shell that may or may not re-coalesce or continue going
off into space. The shell continues to glow due to the heat it already had,
and the heat it receives from the main part of the star.

------
_Microft
There is a zoomable view at
[https://www.spacetelescope.org/images/heic1901a/zoomable/](https://www.spacetelescope.org/images/heic1901a/zoomable/)

~~~
phkahler
What is that bright blob/nebula thing in the upper right of the zoomable
image? That is really pretty. Also, if that's closer than the galaxy how come
we can't resolve individual stars in the blue haze?

~~~
Raphmedia
NGC 604 — a gigantic gas cloud in the Triangulum Galaxy

------
zackhsi
I was having trouble making sense of the figures in the article: "three
million light-years", "40 billion stars"...

So I visited Scale of the Universe [1] to try to get a grip on things.
Wonderful site (and music!), but I think it had the opposite of the desired
effect. I am now completely numb to any notion of trailing zeros.

[1] [http://scaleofuniverse.com/](http://scaleofuniverse.com/)

~~~
lovelearning
Your comment reminded me of the Total Perspective Vortex - "the TPV is the
only known means of crushing a man's soul" :)

[1]
[https://hitchhikers.fandom.com/wiki/Total_Perspective_Vortex](https://hitchhikers.fandom.com/wiki/Total_Perspective_Vortex)

------
warent
I love these kinds of things so much. It makes the universe feel so massive
and vibrant with infinite potential. The sea of stars that make up that galaxy
is absolutely staggering.

Suppose you were on an earthlike planet orbiting some star near the center of
it. Do you suppose the "night sky" would be about as bright as day due to the
number of stars?

~~~
sundvor
Yep, space is just _IMMENSE_ , and this reminds me of the reason why I like
exploration in Elite Dangerous so much - a very beautifully rendered space
game. With a highly realistic space model, it even gets darker as you reach
the galaxy edges.

Apologies in advance to the real scientists here for my naivete, however: As
we know there's billions of galaxies too - it makes me feel like everything is
just a big Mandelbrot set. We've picked galaxies on the top end, and atoms on
the other, but is that really where it ends, or is it just the edges of our
ability to perceive?

~~~
warent
To my amateurish understanding, it does go smaller than atoms, with subatomic
particles like protons which themselves are made of quarks. Beyond that string
theorists would say that there would be strings and that's it. Others might
say some kind of quantum foam.

Going up, galaxies make up groups which combine into superclusters that form
the cosmic web of the observable universe.

So for all intents and purposes, we can essentially say the universe and the
various scales are infinite because it may as well be for humans.

------
tejtm
Some might mostly know this Messier-33, or M33 as an object that may be found
with binoculars or a small scope.

I have seen that bright star forming region in telescopes and it always blows
me away to think it is a nebula in another galaxy. The closest thing we have
to a large star forming region is the Orion nebula but the one there is so big
that if it were where the Orion nebula is, our solar system would be inside
it.

------
dvh
My God, it's full of stars!

~~~
maxxxxx
Judging from the downvotes you should maybe add where this quote comes from...

~~~
taf2
[https://m.imdb.com/title/tt0062622/](https://m.imdb.com/title/tt0062622/)

------
njarboe
Zoom all the way in [1] all the way in to get some feeling of the huge number
of stars. Then think about every one supporting its own civilization at a
scale greater than ours. An awesome thought.

I sure hope interstellar travel is something that intelligent civilizations
do, our galaxy is full of them, and the Fermi paradox is because Earth is in
some sort of nature preserve situation, not because of a great filter we are
yet to encounter.

[1]
[https://www.spacetelescope.org/images/heic1901a/zoomable/](https://www.spacetelescope.org/images/heic1901a/zoomable/)

------
crushcrashcrush
Does anyone know if bubble images are “true color”?

~~~
jzl
Don't know specifically about this one but many aren't. The Pillars Of
Creation isn't[1]. Also we humans can never see most of space in "true color"
with our own eyes, even in a telescope, because the brightness of the incoming
light is so low that our eyes are detecting the photons via color-insensitive
rods rather than cones. Only a time-lapse photo can bring out the real colors.

[1]
[http://hubblesite.org/image/351/news_release/1995-44](http://hubblesite.org/image/351/news_release/1995-44)
\-- "The color image is constructed from three separate images taken in the
light of emission from different types of atoms. Red shows emission from
singly-ionized sulfur atoms. Green shows emission from hydrogen. Blue shows
light emitted by doubly- ionized oxygen atoms."

~~~
ygra
This one [-7] is visible-light and doesn't look too different, though. The
infrared one [2.4] looks very cool, too.

[-7]
[http://hubblesite.org/image/3471/news_release/2015-01](http://hubblesite.org/image/3471/news_release/2015-01)

[2.4]
[http://hubblesite.org/image/3475/news_release/2015-01](http://hubblesite.org/image/3475/news_release/2015-01)

~~~
Keysh
The first image [-7] is basically the same as the classic WFPC2 image jzl was
referring to -- i.e., using the same mapping of emission-line filters to R, G,
and B -- just using a newer camera.

