
Sharpest ever view of the Andromeda Galaxy (2015) - david90
https://www.spacetelescope.org/images/heic1502a/
======
spdustin
Two things are amazing (to me) about this picture.

1) When you look up in the sky at the Andromeda Galaxy, your retina is
absorbing photons that have been screaming through space for 2.5 million
years. If you were on the Earth then, you'd be hanging out with Smilodon, the
saber-toothed cat. For 2.5 million years, those photons were freely zooming
through space and time, and when you see them, those photons are gone forever,
their energy powering a chemical reaction in the rods and cones lining your
retina that enables you to see them. _Those ancient photons_ were seen by
_nobody else_ but you, and they literally become _a part of you_.

2) In about 3.75 billion years, the Andromeda Galaxy, currently zipping
through space toward the Milky Way Galaxy at 110 km/s (nearly 70 miles per
second, or about 250,000 MPH), will collide with and merge with our galactic
home. It's unlikely anything would happen to the majority of planetary systems
in either galaxy (there's a lot of empty space in there) -- but the night sky
(not from Earth, we'd probably be cooked by the Sun by then) sure would be
beautiful. And bright.

Scientists even proposed the name for the new galaxy: Milkomeda.

~~~
yitchelle
I was thinking a similiar thing last night when I read this news. What we
observed through the Hubble telescope now about the Andromeda Galaxy happened
2.5 millions years ago. What is it actually doing right now? Is it still
alive?

~~~
pc86
On an astrological scale isn't 2.5 million years a very, very short period of
time?

~~~
JoeAltmaier
Yes. Our own galactic 'year' is 250 million years (the time it takes to rotate
in place once). So 2.5 million years is about a galactic day (or maybe a
weekend).

~~~
yitchelle
Wow, I feel so small, physically and temporally!

------
mutagen
This is the imagery released in January 2015. Though not brand new, this is an
amazing image to contemplate, especially in light of the continued discoveries
from Kepler.

Edit: Don't miss the link in the article to the slippy map zoomable version at
[https://www.spacetelescope.org/images/heic1502a/zoomable/](https://www.spacetelescope.org/images/heic1502a/zoomable/)

~~~
sndean
Sorry if this is a dumb question (the article pretty much says it): when you
zoom all of the way in, each dot is a star (or cluster of stars)?

~~~
elorant
Not really, but close. Picture is 1.5 billion pixels and features 100 million
stars. So it’s about one star per fifteen pixels.

~~~
captaincrowbar
100 billion stars, not million. So on the order of 100 stars per pixel,
although obviously not evenly distributed.

(Edited to add) The individual stars you can see when you zoom all the way in
are the very brightest stars, mostly blue (O/B class) or red (K/M class)
giants. For each star you can see, there are hundreds of smaller stars that
you can't make out individually but contribute to the general background glow.

~~~
mevile
> 100 billion stars, not million

No, it's 100 million, as the article says.

> It is the biggest Hubble image ever released and shows over 100 million
> stars and thousands of star clusters embedded in a section of the galaxy’s
> pancake-shaped disc stretching across over 40 000 light-years.

~~~
planteen
I think maybe the op meant the entire Andromeda galaxy is estimated to have
200-400 billion stars (source Wikipedia)

~~~
haukur
Actually, Wikipedia says the number of stars is estimated at 10^12 (a
trillion).

~~~
sdenton4
(And whoever guesses the closest gets the whole jar!)

------
ianbicking
I'm having a hard time understanding this picture along with what I understand
of the scale of space. The Andromeda Galaxy is big, and it has a lot of stars.
Which is to say, it's REALLY big, and it merely has a bunch of stars, so the
size of the stars should be very small compared to the empty space between the
stars, even if you are looking through the galaxy. I would assume that if you
get a better and better image, you'll be seeing the holes better just like
you'll see the stars better. Kind of a fractal effect: when you look closer,
you see the same kind of density but at different scales.

But if I zoom into this image it just feels like I'm seeing a mush of speckled
light. What's up with that? How much of the image is an artifact of the
telescope?

~~~
DanielBMarkham
Not an astronomer, but I'll give it a shot.

If you do the zoom thing, at the highest level? Yes, it's a mush of speckled
light -- looks a lot like a noisy or grainy RGB image.

But what I _think_ you're seeing are the actual stars -- thousands or maybe
ten thousands of them in a full screen at the highest zoom. They're all
clumped together because you're looking cross-wise at the galaxy, through the
disc. So there so many stars at the highest level of zoom that the image looks
grainy.

~~~
QuantumRoar
As a somewhat astronomer, this explanation seems reasonable.

Usually you can't discern individual stars in another galaxy, like in the
center of the Andromeda galaxy (But doing statistics is still possible).
However, the Andromeda galaxy seems close enough that at the outer edge of it,
you can isolate them to do astronomy on individual stars (like spectroscopy).

Edit: Also, you can find stars in almost all colors. The average of the colors
depends on the age of the stars in the galaxy. If there are only a few new
stars born, the galaxy will appear redder. If there are many new stars born,
it appears bluer (see Hertzsprung-Russel diagram). The way the stars appear in
different colors means that they have different ages and masses.

Noise in a telescope (except for high energy particles hitting your detector)
is thermal noise. It will only appear if there's almost no light detected. So
if it were noise, it should be the other way round: Noisy where there are
little stars and no noise where there are a lot of stars. If you'd ask me, I'd
say there's exactly zero visible noise in there.

~~~
antognini
As a former astronomer, this is correct. Even in extremely high resolution
images each pixel contains many, many stars. This fact has actually been used
to determine the distances to galaxies. The basic idea is that if the galaxy
is nearby, then there will be fewer stars per pixel (say, only a few dozen),
but if the galaxy is very far away, there will be many thousands of stars per
pixel. As a result, if the galaxy is nearby, there will be a lot of variation
in brightness from pixel to pixel because the Poisson fluctuations are
proportionally much larger. If the galaxy is more distant, the brightness at
each pixel will be more homogenous. This is called the surface brightness
fluctuation technique.

There's a nice page about it here:
[https://ned.ipac.caltech.edu/level5/Jacoby/Jacoby9_1.html](https://ned.ipac.caltech.edu/level5/Jacoby/Jacoby9_1.html)

------
lovelearning
I was wondering why every star showed a pair of perpendicular lines radiating
out. Apparently they are artifacts of the telescope's construction, and are
called "diffraction spikes" [1].

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

~~~
mikk14
There is a nice Minute Earth video about this, for those who want a quick and
entertaining way to get the concept:
[https://www.youtube.com/watch?v=VVAKFJ8VVp4](https://www.youtube.com/watch?v=VVAKFJ8VVp4)

------
kowdermeister
It recently struck me, that if Andromeda would be visible to the naked eye, it
would be huge on the night sky:

[http://sploid.gizmodo.com/the-incredibly-huge-size-of-
androm...](http://sploid.gizmodo.com/the-incredibly-huge-size-of-
andromeda-1493036499)

~~~
planteen
It is visible to the naked eye. It looks more like a cloud and doesn't have as
large of an apparent diameter though.

~~~
BurningFrog
I think the center is faintly visible. Doubt you can make out the whole thing.

~~~
Florin_Andrei
Correct. Only the core is visible to the naked eye, and even then you'd have
to be out in the boondocks, far from cities and other light polluters.

------
mholt
I've had this image downloaded at full res for over a year now, and I love to
project this at actual size onto my wall (with some good, mysterious mood
music). Makes a really neat effect and is fascinating to look at once you
realize what you're gazing upon. It's even a good conversation starter. (I'm
fun at parties...)

Just scrolling the image around in Preview makes my Mac slow to a crawl.

~~~
camiller
"...I love to project this at actual size onto my wall ..."

you have a 40,000 light year wall in your house?

~~~
mholt
I meant that the image is not zoomed out and it pans across the width and
height of the image on the wall. ;)

------
redtuesday
If you like this you might also enjoy this [1] 46 billion pixel image of our
own galaxy (sadly not as sharp as the andromeda one). Taken from a link [2] I
posted a while back.

[1] [http://gds.astro.rub.de/](http://gds.astro.rub.de/)

[2] [http://aktuell.ruhr-uni-
bochum.de/pm2015/pm00143.html.en](http://aktuell.ruhr-uni-
bochum.de/pm2015/pm00143.html.en)

------
fjarlq
I've enjoyed this video exploration of the image:

Gigapixels of Andromeda:
[https://www.youtube.com/watch?v=udAL48P5NJU](https://www.youtube.com/watch?v=udAL48P5NJU)

------
brooklyndavs
Beautiful. Whenever I see images like this of "big things" in space I'm
reminded how meaningless our short existence on this little rock is from a
universal perspective. My big takeaway is always to try to find personal
meaning in ones life. Either in work, or family, hobbies, etc.

~~~
akuma73
It's taken 15 billion years since the big bang for our relatively complex
atoms to form - from supernovae. Yes, we were generated in the core of stars.
The entire superstructure of the universe is what allows us to exist in the
first place.

------
dreamsofdragons
This is an ignorant question, but when you zoom in full, is every light dot a
star? Or is it noise, like you get with a poorly lighted photo?

~~~
miahi
At 100% zoom you will see that they have different sizes. Noise has usually
the same size (the size of one pixel on the sensor, if not using bayer
filtering).

Then you take a look at the XDF[1], showing ~5500 galaxies like this one in a
tiny angular diameter, and you realize how big the Universe is.

[1]
[http://hubblesite.org/newscenter/archive/releases/2012/37/im...](http://hubblesite.org/newscenter/archive/releases/2012/37/image/a/)

~~~
TheSpiceIsLife
It's cool hey! That image covers the same area as approximately four full
moons, 2.3 arcminutes by 2 arcminutes. [1]

So, back of the envelope calculation multiplying 5500 by the area of the full
sky (as though the earth were invisible) we get ~242 billion galaxies, which
is close to what this[2] claims at 100 to 200 billion galaxies.

Space is _big_.

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

2\. [http://www.space.com/25303-how-many-galaxies-are-in-the-
univ...](http://www.space.com/25303-how-many-galaxies-are-in-the-
universe.html)

~~~
gshubert17
The moon is about 30 arcminutes across (half a degree) [0], which is
considerably larger than the area of the Extreme Deep Field. But the estimate
of the number of galaxies is okay.

The Hubble Ultra-Deep Field (of which the Extreme Deep Field is a part) is one
thirteen-millionth part of the full sky. [1]

The full sky is about 41,253 square degrees in size. [2]

I think the HXDF is one 32-millionth of the full sky. If so, multiplying 32
million by the 5500 galaxies in the XDF gives on the order of 200 billion
galaxies, as you said.

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

[1] [https://en.wikipedia.org/wiki/Hubble_Ultra-
Deep_Field](https://en.wikipedia.org/wiki/Hubble_Ultra-Deep_Field)

[2]
[https://en.wikipedia.org/wiki/Square_degree](https://en.wikipedia.org/wiki/Square_degree)

~~~
TheSpiceIsLife
Yes, you're right, thanks for the correction: the Extreme Deep Field image is
smaller than the moon. I neglected to click on the image at [1], thereby
missing the detail in the full size image[2].

1\.
[https://en.wikipedia.org/wiki/Hubble_eXtreme_Deep_Field](https://en.wikipedia.org/wiki/Hubble_eXtreme_Deep_Field)
2\.
[https://en.wikipedia.org/wiki/Hubble_eXtreme_Deep_Field#/med...](https://en.wikipedia.org/wiki/Hubble_eXtreme_Deep_Field#/media/File:XDF-
scale.jpg)

------
meeper16
Using the zoom tool recommended in the article really provides perspective.
Especially when you see those stars clustered close together when each of them
are really millions of miles apart (aside from the binaries) with possible
planets orbiting them. Now consider the billions of galaxies out there. I'm
positive there's an Alien or two there as well.

~~~
cgriswald
You're off by an order of magnitude.

Stars are often trillions of miles apart. Binaries can be so close they touch
or as far apart as 100 billion miles.

As for the aliens, there are good arguments for and against their existence.
The numerical argument is not, by itself, very convincing. It's like thinking
you will win the lotto because you have a million tickets, but not knowing how
many balls are drawn and how many numbers are on the balls. You may be
guaranteed to win, or your odds may be effectively zero.

~~~
meeper16
I suppose my mistake made it an order of magnitude more amazing!

------
javanix
Link to full resolution downloads:
[http://hubblesite.org/gallery/album/galaxy/pr2015002a/titles...](http://hubblesite.org/gallery/album/galaxy/pr2015002a/titles/true/hires/true/)

~~~
andrewd18
Original size: A mere 4.3 GB.

------
PhantomGremlin
Another really great picture taken by Hubble is the eXtreme Deep Field. As
wiki puts it: _Except for a few stars, every speck of light is an entire
galaxy – some of these are as old as 13.2 billion years_

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

I occasionally use that image as my desktop. It reminds me of how
insignificant we really are.

------
maroonblazer
I'm not an astronomer as evidenced by this question:

What's the bright glowing light that's partially cropped in the lower left of
the image? Is that a large star cluster? Or a single star? Or something else?

~~~
6nf
Yes it's a large cluster of stars. At the very center of the galaxy you will
also find a supermassive black hole.

~~~
Zaheer
Is there a name for that super massive black hole? (serious question) Just
curious to learn more.

~~~
spdustin
I don't believe they've ever named it; it is indeed "supermassive" (around 2.3
billion of our suns).

The supermassive black hole at the center of the Milky Way is called
Sagittarius A* ("Sagittarius A-Star"), the only named supermassive black hole
I could find in any reports.

------
LoSboccacc
the image is lovely. the zoom tool is missing a feature to link at specific
places - like, there's a galaxy visible trough the background at a certain
place, but you cannot share it

also it's surprisingly detailed and noisy, where usually it's an either or. It
makes me suspect the noise it's actual stuff absorbing/emitting radiation, but
I have no idea what's the interference to be expected from dust or if those
dots and speckles are all actual stars - anyone has a link with some
explanation of what we're looking at?

------
rdiddly
I'm gonna go out on a limb and say "pancake-shaped disk" is not only redundant
(because all disks are pancake-shaped) but backwards (since actually it's
pancakes that are disk-shaped - pancakes are a special case of disks, which
are really cylinders).

Sorry, this is more fun for me than marveling at the photo. It is pretty cool
though.

------
huuu
Does anyone know why those patterns [1] appear when you zoom in like 10 steps
or so? Are those stitches or some artifacts of the sensor?

[1]
[http://www.spacetelescope.org/images/heic1502a/zoomable/](http://www.spacetelescope.org/images/heic1502a/zoomable/)

~~~
MaulingMonkey
Not sure what patterns you're referring to. Also not sure how big a "step" is
- zooming is continuous for me. Might check other browsers (I'm using Chrome)?
Or link a screenshot?

~~~
euyyn
I guess he refers to clicking the + button ten times. I'm using Chrome for
Android myself.

~~~
cgriswald
He may be referring to that, but there doesn't seem to be a per-click zoom
amount. It zooms further the longer you hold a click and seems very sensitive.

------
ThePhysicist
My god, it's full of stars!

------
bunkydoo
This is extremely cool. I remember going to the observatory as a kid and
looking at Andromeda through the telescopes. It's amazing to think we will be
one with that galaxy someday, millions of years from now

------
netgusto
"the full image [...] has 1.5 billion pixels. You would need more than 600 HD
television screens to display the whole image."

True, but not accurate ?

1'500'000'000 / (1980 * 1024) ≈ 739.8 :)

~~~
aruggirello
That should be:

1'500'000'000 / (1920 * 1080) ≈ 723.38

Anyway, as you wouldn't want to crop the image you're showing, a more suitable
formula would be:

N = ceil(image width / 1920) * ceil(image height / 1080)

Edit: width = 69536, height = 22230 so N = 37*21 = 777

~~~
e12e
I'd love to see this done with ~200 4k screens ...

------
127
Wait? That's not digital noise? Those are actual stars?

------
mixmastamyk
It's interesting how uniform Andromeda is. Not much in the way of arms.

Also I'm impressed with the resolution available, you can really zoom in an
incredible amount.

------
jonathansizz
It would be nice if they could filter out the intervening objects that are in
our own galaxy, to give a clearer perspective.

------
planteen
Fun fact: Andromeda is the only object outside of the local Milky Way group
that can be seen with the naked eye.

~~~
jonathansizz
M33 in Triangulum is comfortably visible with the naked eye from dark skies. A
few other galaxies have been claimed to have been spotted with the naked eye,
although I've never been able to see any of these.

Also, the 'local group' actually includes M31 and M33 in addition to our
galaxy and many smaller ones.

~~~
planteen
You are right. Should have fact checked that before posting.

------
highCs
What is so bright on the left side -- what looks like the center of the
galaxy?

~~~
CiPHPerCoder
A lot of stars cluster around the supermassive black holes in the center of
every galaxy. Also, depending on the area of the spectrum they were examining,
a lof X-rays are found there too.

------
daxfohl
Hmm, expanding zoom tool across three 4k monitors crashes chrome.

------
cordite
They sadly don't have background pics for 4K screens.

------
kristopolous
is there anything of statistical or other cosmological analytics merit here or
is this just for enjoyment?

------
robmcvey
mind well and truly blown

