APOD: The Fornax Cluster of Galaxies (2016 Jun 11)

[APOD Robot]

The Fornax Cluster of Galaxies

Explanation: Named for the southern constellation toward which most of its galaxies can be found, the Fornax Cluster is one of the closest clusters of galaxies. About 62 million light-years away, it is almost 20 times more distant than our neighboring Andromeda Galaxy, and only about 10 percent further than the better known and more populated Virgo Galaxy Cluster. Seen across this two degree wide field-of-view, almost every yellowish splotch on the image is an elliptical galaxy in the Fornax cluster. A standout barred spiral galaxy NGC 1365 is visible on the lower right as a prominent Fornax cluster member. The spectacular image was taken by the VLT Survey Telescope at ESO's Paranal Observatory.

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[/b]

[Ann]

Click to view full size image

NGC 1365, or is that a primula flower?

A galaxy cluster made up almost exclusively of yellow blobs is rather boring to me. So I look for any little spot of blue to relieve the boredom. In the Fornax Cluster, majestic barred spiral NGC 1365 sticks out like a sore thumb (or like a blue and yellow primula flower). NGC 1365 looks splendid, but then again, I've seen so many pictures of that galaxy that nowadays I get a sort of Orion Nebula reaction when I see it all over again.

Click to view full size image

Irregular galaxy NGC 1427A.
NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

So instead of ogling NGC 1365 (again), my eyes were drawn to an almost teardrop-shaped blob at far left in today's APOD. I knew I had seen it before, but certainly not so many times that I was losing even a bit of interest in it. The object in question is NGC 1427A, a bright irregular dwarf galaxy from the surrounding deep intergalactic wilderness that got lured in and trapped like an animal. Now it is plunging to its doom in the mean, mean gravity well and hot intracluster gas of the Fornax cluster. The poor thing is bleeding blue blood, sweating blue tears and crying blue tears as it is falling like a tasty morsel into the jaws of the frightfully obese yellow blobs! (I apologize for the non-yellow color of this particular hungry blob.)

Ann

[heehaw]

Will humans ever go to the Fornax galaxies? I know it seems a silly question. Ten thousand years ago, humans chatting on the west coast of Ireland might quite well have asked -- perhaps they did -- 'will folks like us ever cross this vast Atlantic ocean, to see if there are other lands?' It would have seemed impossible. It certainly seems impossible that humans could cross the gulf to Fornax. The Irish had (I expect) hollowed logs that allowed them to cross the Irish lakes. We have today ships, or could soon have, that could take us to the other planets (Mars the only one worth going to, we know already). But Alpha Centauri is 4 years away at the speed of light, and that is more than just problematic! To visit more distant stars, people would have to be frozen, and could only return to their descendants' future. Are there wormholes? Can we make them? Gross speculation. Carl Sagan had fun with it, abetted by Kip Thorne......

[geckzilla]

I think the comparison of crossing an ocean on earth to crossing the cosmos creates a false dichotomy. The argument is as follows: Humans once thought crossing an ocean was impossible, but then they did it. Now they think crossing a galaxy is impossible, but because they crossed an ocean that was thought impossible to cross, so too space travel across vast distances must be possible.

Space is not an ocean. Just like we aren't going to build a submarine that can travel around in the Sun's plasma, we probably aren't going to build a ship that can take us quickly to the next star, let alone the next galaxy.

[Asterhole]

I think the comparison of crossing an ocean on earth to crossing the cosmos creates a false dichotomy. The argument is as follows: Humans once thought crossing an ocean was impossible, but then they did it. Now they think crossing a galaxy is impossible, but because they crossed an ocean that was thought impossible to cross, so too space travel across vast distances must be possible.

Space is not an ocean. Just like we aren't going to build a submarine that can travel around in the Sun's plasma, we probably aren't going to build a ship that can take us quickly to the next star, let alone the next galaxy.

I just like it that you used the word "dichotomy".

Interstellar or intergalactic travel if ever possible may not even involve a vehicle of any sort. I consider the means used in Dan Simmons' Hyperion sci-fi saga where one would merely step through a portal and POOF! you are there.

[emc]

I spend a lot of time on the other side of our visible universe in the realm I like to call "storage space" (cause there's probably gobs of room) and I don't even own a spaceship.

Today's APOD seems at first glance a little "seedy"... But it's probably just me.

[kenkilgore]

Isnt't the Andromeda galaxy about 2.5 lys away from us? If so, the Fornax cluster of galaxies would be OVER 20 times the distance to Andromeda, not "almost"....

[bystander]

http://asterisk.apod.com/viewtopic.php?t=35831

Click to view full size image

[neufer]

Isn't the Andromeda galaxy about 2.5 [million] lys away from us? If so, the Fornax cluster of galaxies would be OVER 20 times the distance to Andromeda, not "almost"....

The Fornax cluster of galaxies is almost 25 times more distant than our neighboring Andromeda Galaxy.

[rstevenson]

Will humans ever go to the Fornax galaxies? ...

Well, as Geck said, you've set up a false dichotomy. Let's run some numbers to see how they compare...

On average, Mars is 12.5 light-minutes from Earth, or about 1/42077 of a light-year.
The Fornax galaxy cluster is said to be 62 light-years away.
So the Earth to Mars distance is 1/2608762 of the distance to the Fornax cluster.

Humans messing around in boats managed to get from the English isle to the isle of Ireland, a crossing of about 20 km.
From Ireland to, say, Newfoundland is about 3220 km.
The ratio of the first of those to the second is about 1/161.

Comparing our spaced-out 1/2608762 to the all-wet 1/161, we find that the sea crossing is less difficult (only in terms of relative distance travelled) than our space voyage by a factor of about 16200.

But I've just compared kilometers to light-years! I can fix that: a ly is 9.461e+12 km, so the actual distances being compared work out to a ratio of 8.332e+15. (Anything with 15 zeros after it is A Really Big Number.) We should divide that by some suitable ratio based on the speed for each mode of travel, but that's where things get a bit dicey...

Not only do we not know how fast the first Irish paddled, but the above calculation carries with it the implication that with advances in technology, we can travel at the speed of light. But we know of no technology that can get us anywhere near the speed of light. The best being thought of today might get us towards 10% of light-speed, at what is likely to be extreme risk to all aboard. So we need to add (at minimum) a further factor of 10, making the space voyage about 8.332e+16 times longer (still ignoring the required -- but my head hurts -- speed ratio) than the wandering surfers experienced.

In short, we'd need to have some sort of technology that would appear to us today to be magic to have any hope of trying such a trip. I can just stretch my mind to encompass some short interstellar travel in the coming centuries, by a few crazy explorers or in-stasis colonists -- but more likely, just by bots.

I must conclude that, compared to wandering around our corner of our galaxy, the Fornax cluster is beyond unreachable.

Rob

[darksky2500@gmail.com]

>>>>>
The Fornax galaxy cluster is said to be 62 light-years away
>>>>>

62 *million* light years away. Not a trivial error. Your point stands rstevenson.

[rstevenson]

You're right. A million here, a million there, pretty soon we're talking real distance.

Rob

[Ann]

>>>>>
The Fornax galaxy cluster is said to be 62 light-years away
>>>>>

62 *million* light years away. Not a trivial error. Your point stands rstevenson.

Click to view full size image

The Big Dipper. Source:
http://www.skyandtelescope.com/astronom ... ds-a-star/

Indeed, your point stands, Rob. But all the bright stars of the Big Dipper are farther away from us than 62 light-years, and if the Fornax Cluster was 62 light-years away, it would be between us and the Big Dipper.

Dad, what is the Fornax Cluster like?

Well, son, the galaxies of the Fornax Cluster are very, very small...

Ann

[K. Trout's Cousin]

Just like we aren't going to build a submarine that can travel around in the Sun's plasma, we probably aren't going to build a ship that can take us quickly to the next star, let alone the next galaxy.

It's not probable that we'll survive anther century, but it's possible. It's also possible we'll learn to harness dark energy to make the interstellar/intergalactic trip regardless of the probabilities involved or the method that dictates. If you don't consider possibilities you won't even try to find a way. What point robotic missions to the other planets in the solar system if not to examine the possibilities they hold for us? What point science?

[neufer]

Just like we aren't going to build a submarine that can travel around in the Sun's plasma, we probably aren't going to build a ship that can take us quickly to the next star, let alone the next galaxy.

It's not probable that we'll survive anther century, but it's possible. It's also possible we'll learn to harness dark energy to make the interstellar/intergalactic trip regardless of the probabilities involved or the method that dictates.

<<The Infinite Improbability Drive is a wonderful new method of crossing vast interstellar distances in a mere nothingth of a second, without all that tedious mucking about in hyperspace. It was discovered by a lucky chance, and then developed into a governable form of propulsion by the Imperial Galactic Government’s research team on planet Damogran.

The principle of generating small amounts of finite improbability by simply hooking the logic circuits of a Bambleweeny 57 Sub-Meson Brain to an atomic vector plotter suspended in a strong Brownian Motion producer (say a nice hot cup of tea) were of course long understood – and such generators were often used to break the ice at parties by making all the molecules in the hostess’s undergarments leap simultaneously one foot to the left, in accordance with the Theory of Indeterminacy.

Many respectable physicists said they weren’t going to stand for this, partly because it was a debasement of science, but mostly because they never got invited to those sorts of parties. Another thing they couldn’t stand was the perpetual failure they encountered in trying to construct a machine which could generate the infinite improbability field needed to flip a spaceship across the mind-paralyzing distances between the farthest stars, and in the end they grumpily announced that such a machine was virtually impossible.

Then, one day, a student who had been left to sweep up the lab after a particularly unsuccessful party found himself reasoning this way: If, he thought to himself, such a machine is a virtual impossibility, it must logically be a finite improbability. So all I have to do in order to make one is to work out exactly how improbable it is, feed that figure into the finite improbability generator, give it a fresh cup of really hot tea… and turn it on!

He did this, and was rather startled to discover that he had managed to create the long-sought-after golden Infinite Improbability generator out of thin air, which passes through every point in the universe simultaneously so there is no telling what species you will be before Normality is restored. It startled him even more when just after he was awarded the Galactic Academy’s Prize for Extreme Cleverness he got lynched by a rampaging mob of respectable physicists who had finally realized that the one thing they really couldn’t stand was a smart-aleck.

The drive's first installation in a spacecraft, the Starship Titanic, to ensure that it was Infinitely Improbable that anything would ever go wrong with any part of the ship, went horribly awry because the engineers did not realize that with the quasi-reciprocal and circular nature of all Improbability calculations, anything that was Infinitely Improbable was actually very likely to happen almost immediately. The ship underwent total existence failure almost immediately. After being perfected, the drive was successfully installed in the starship Heart of Gold, where it mostly worked fine aside from the occasional tendency to, against all probability, pick up unexpected passengers by itself.>>

[Ann]

Just like we aren't going to build a submarine that can travel around in the Sun's plasma, we probably aren't going to build a ship that can take us quickly to the next star, let alone the next galaxy.

It's not probable that we'll survive anther century, but it's possible. It's also possible we'll learn to harness dark energy to make the interstellar/intergalactic trip regardless of the probabilities involved or the method that dictates. If you don't consider possibilities you won't even try to find a way. What point robotic missions to the other planets in the solar system if not to examine the possibilities they hold for us? What point science?

There are a couple of small problems about harnessing dark energy in order to travel to other stars or galaxies:

1) We don't know what dark energy is.

2) We don't know where dark energy is, except that it seems to be everywhere.

3) Assuming that we do manage to identify the nature of dark energy and its exact whereabouts, we wouldn't know how to concentrate it in or around our own spaceships, so that we could use it as propulsion.

4) Assuming that we do manage to identify its nature and its exact whereabouts and concentrate it to use as propulsion, we wouldn't know how to make dark energy push us towards other stars or other galaxies, when we know that its nature seems to be to expand space and push galaxies away from each other.

5) There is the little problem of making anything made of matter travel above, at or near light speed. Throwing dark energy into the mix doesn't seem to solve any of those problems.

The best way to travel to other galaxies does indeed seem to be to use the Infinite Improbability Drive. But since no one has any idea whatsoever how to turn a nice cup of tea into faster-than-light interstellar travel, it would seem that science fiction is the realm where we can quickly and easily travel to other stars. Reality, whose nature is at least partly described by Einstein's Theory of General Relativity, is a very poor choice of a place to make such journeys become reality.

Ann

[DavidLeodis]

I would be grateful if someone can help me with information about the image. In information that I was able to obtain through the APOD image properties it stated "Metadata Date 2016:04:12 12:20:20.307198" and "Date Created 2016:04:13 12:00:00". The Date Created is the same as the date when the image was released, presumably using data obtained earlier. What though is the Metadata Date? If it is that when the last data was obtained then the image was created remarkably soon after. Thanks for any help .

PS. The Metadata Date time is extremely precise!

[Chris Peterson]

I think the comparison of crossing an ocean on earth to crossing the cosmos creates a false dichotomy. The argument is as follows: Humans once thought crossing an ocean was impossible, but then they did it. Now they think crossing a galaxy is impossible, but because they crossed an ocean that was thought impossible to cross, so too space travel across vast distances must be possible.

Space is not an ocean. Just like we aren't going to build a submarine that can travel around in the Sun's plasma, we probably aren't going to build a ship that can take us quickly to the next star, let alone the next galaxy.

Something else to consider is that we can look across our "ocean" and see what's out there, and how far away. It lets us actually make reasonable estimates as to possibilities (slim to none, of course). Pretechnological humans standing on seashores couldn't see anything at all. They didn't even know if there was another side that could be reached.

It would be as if we lived in a dark universe and could see nothing at all beyond our own planet. How would that influence our ideas about space travel and crossing space?

[geckzilla]

I don't think this forum would even exist and we wouldn't even bother to ask the question in that case... The tides, seasons, and all sorts of things might never make any sense to us at all!

[Ann]

I don't think this forum would even exist and we wouldn't even bother to ask the question in that case... The tides, seasons, and all sorts of things might never make any sense to us at all!

There could be huge numbers of worlds out there that have life under the surface of an ice-covered ocean. Some of them might have advanced life. Would they ever consider the possibility that there might be an "out there"?

Ann

[geckzilla]

Living in an ocean seems like it would be a great barrier. Perhaps that's where most intelligent life lives, but they can't be bothered to launch rockets.

[bruceyoung57]

I don't see any foreground stars in this picture of the Fornax Cluster of galaxies. If not all the blips of light in the background would also be galaxies. Is this the case?

[geckzilla]

I don't see any foreground stars in this picture of the Fornax Cluster of galaxies. If not all the blips of light in the background would also be galaxies. Is this the case?

There are a couple dozen bright ones and several hundred dimmer ones, by my estimation. The point spread function, that is the way the light from a point source interacts with the telescope, is a little more subtle in this case. Rather than large and conspicuous diffraction spikes, the stars appear as round spots with a few rays emanating from the center. This pattern is much easier to see in the brightest stars, but it is followed all the way down to the dimmest stars, even if we can't see it. Some very dim stars are nearly indistinguishable from distant background galaxies.