Since we’ve been talking about snow quite a bit recently, this seems fitting. WUWT reader Tom in Texas tips us to this image:
A composite of archival Hubble data taken with the Wide Field Planetary Camera 2 and the Advanced Camera for Surveys. Like a whirl of shiny flakes sparkling in a snow globe, Hubble caught this glimpse of stars in the globular cluster M13. The cluster is home to over 100,000 stars, packed closely together in a ball approximately 150 light-years across, and is located at a distance of 25,000 light-years. Picture: AFP / NASA / ESA
Click here to see a high-res version of the Hubble snow globe I wonder what the sky would look like from a world in the center of that cluster? Would some of the stars look like bright marbles in the sky?
If you really want to see some interesting things from the HST, have a look at this gallery:
Hubble Space Telescope Advent Calendar 2009
Like the photo above, it gives some perspective about our place and scale in the universe.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
gtrip (23:57:08) :
Leif Svalgaard (23:33:00) :
Not at all. The solar wind filling the solar system has a ‘temperature’ of some 20,000C [right this minute] and we see the planets quite well.
I apparently don’t have the knowledge you have Leif, but I can’t help but question your claim. Does that include our solar system? And if so or if not, at what speed is it traveling? And is it losing temperature as it travels? And if so, at what rate?…just asking
Not sure which claim you’re questioning? The fact that there is a solar wind or the fact that it’s at approx 20,000 degrees?
You have to remember that the density of the material in question is of fundamental importance – you can have a medium that is extremely “hot” (say millions of degrees) but if it is suitably “thin” or sparse then you could easily put your hand in it without ill effect. When dealing with interstellar material the densities are often very low (relative to what we’re used to on earth they can essentially approach a vacuum).
From what I remember (would have to dig out the old text books or even Google it…) the solar wind(s) travel at anywhere between 400-800km/s – and I assume it loses “temperature” as it travels. (I presume the loss rate is a balance between the radiation from the particle as a black-body to space against any solar radiation incident on the particle, the latter obviously diminishing as the particles get farther from the sun – this assumes that conduction effects are minimal in the medium).
Of course I could be wrong about all of the above – it’s been a while…
Cheers
Mark
For an extraordinary photo of the Tarantula Nebula
http://www.eso.org/public/images/eso0650a/
And wide-field images
http://canopus.physik.uni-potsdam.de/~axm/images.html#wide-field
Have a Happy New Year
Mal
Leif, I think gtrip has confused temperature with heat density. The solar wind is very hot, but it also has a low heat density which is why the Earth doesn’t ‘burn up’ by being inside a 20,000+ C gas. The gas is too tenuous to do that.
len (00:36:34) :
If you’re really interested in proper gravity knowledge, go to http://astrowww.phys.uvic.ca/~tatum/ under celestrial mechanics section. All the equations you need are there. He covers all, integration too, from ground up and is quite thorough. I think you’ll like it for a reference. Its one of mine.
Leif, gtrip and Graeme, you have it all wrong.It is 20,000 million degrees 2 miles down.
Happy New Year everyone.
It is cut off. The HST field of view is very narrow.
M13 is actually quite accessible with an amateur telescope, and just as beautiful. Here is one of my backyard images of it:
http://arnholm.org/astro/deepsky/m13/m13_20060416.jpg
There is lots of stuff out there. If you look in the 11 o’clock position in my image, near the top, you see a spiral galaxy called NGC6207.
The universe is a beautiful place. Reality beats fantasy.
gtrip: as Graeme suggests, one problem you seem to be having in believing Leif’s statement is a confusion between the definitioms of temperature and heat (not heat density per se). There also seems to be some confusion regarding temperature and black bodies. Black bodies are a hypothetical construct which many large, energetic objects (like the Sun) can be reasonably approximated as. Small particles (like those is the solar wind) are almost completely electrons, ionized atoms and very simple molecules, and electronically excited neutral atoms and very simple molecules. These particles by *no means* behave anything like a black body. They radiate and absorb energy not by classical black body laws (at rates proportional to their tenperate to the fourth power) but by quantum mechanical laws which are governed by state densities and electronic selection rules (i.e., they absorb and emit only at very specific and very narrow portions of the spectrum).
This also means that the whole ensenble is almost perfectly transparent at wavelengths where there are no existing transitions or the transitions are disallowed by selection rules. Even where allowed transitions exist, as suggested earlier, the particle density is so low that it would have little impact. So, for instance, the earth’s atmosphere would almost certainly have a larger total absorption at almost any absorption or emission frequency than the solar wind. This is why you have to use a space-based instrument to see it and it’s still hard work doing so.
Hope that helps.
I am sure that with proper adjustments and appropriate value added data, the solar wind is getting warmer.
Wonderful stuff. Yet there are people who claim they can define the creator of all that glory. I wonder if they have ever looked through a telescope or even looked at the Hubble pictures.
Fun to image, but still a bit of a challenge to get that just-right image stretch:
http://www.robertb.darkhorizons.org/m13c.jpg
When NASA annouced they were going to abandon Hubble some years ago, the imagination went wild. What amatuer astronomer wouldn’t want a 96″ RC in his backyard?
Carsten Arnholm, Norway (02:42:09) :
You can see the red stars in M13 through a 25″ Dob (as red stars).
These Hubble photos are the very best of this Internet thingy. The photo series at boston.com are routinely amazing. Thanks for the link.
Pamela Gray (00:13:11) :
Do I see double Sun’s? These are Suns that rotate around each other.
Pamela Gray (00:23:15) :
Or are those galaxies rotating around each other?
What you need to visualise is that all those stars are in space – so they’re not just sitting there. All of them are in orbit within the globular cluster – many of these orbits highly elliptical, around the cluster centre of gravity, so many of the stars zoom in to near the centre of the cluster, then crawl out to its outer edges.
Then this, and other globular clusters, are in orbit in a spherical cloud around our Galaxy. Globular clusters can be seen around other galaxies as well.
Yes, some (many?) of them will be double stars. Also, because of the closeness of the stars in the centre, they interact gravitationally, so existing multiple systems could be separated, and new ones formed. There’s a report on that suggestion here.
(They are stars in the cluster, not galaxies – though there could be some distant background galaxies in the image.)
Great image – though I still don’t think it beats staring up at the real sky in a truly dark location, with no Moon and a bright Milky Way, and visualising the disk of our galaxy, with the Sun and all its planets orbiting through the disk of stars.
Andrew Parker (22:51:53) :
O.K., if the solar system is currently hurtling through a 6000 C gas cloud, how does that affect optical accuracy?
Leif Svalgaard (23:33:00) :
Not at all. The solar wind filling the solar system has a ‘temperature’ of some 20,000C [right this minute] and we see the planets quite well.
gtrip (23:57:08) :
but I can’t help but question your claim. Does that include our solar system? And if so or if not, at what speed is it traveling? And is it losing temperature as it travels? And if so, at what rate?…just asking.
Leif Svalgaard (00:42:06) :
On what ground would you question this?
Our solar system is filled with a hot gas [called the solar wind] with a temperature varying between 10,000C and 100,000C or more. Right now the temperature is 27,100 C. The Earth is travelling through this gas at a speed of 30 km/sec. The solar wind is expanding and the temperature is slowly decreasing, but remains hot throughout.
There is a major difference in the gases in the solar wind than in a (much cooler) interstellar gas cloud. The solar wind is so hot, that all of the gases are completely stripped of their electrons. The solar wind is mostly an equal mix of protons and electrons. Spectrographic analysis of the solar corona performed during a total solar eclipse confirms that the very high temperatures existing in the corona ALTERS the spectra of the gases. To assume that the solar wind and an interstellar gas cloud would have the same optical qualities because they are both comprised of the same gases is a fallacy.
I have worked with helium (He) excited to a plasma state inside an Inert Gas Plasma Generator in a laboratory, and have observed that the helium in plasma form partially occludes visible light. This is with only a 5 inch thickness of plasma inside a clear quartz vacuum chamber evacuated to a pressure of 100 millitorr. The helium plasma I observed would be much closer in temperature to an interstellar gas cloud, than is the solar wind to such a cloud.
“One good lab experiment is worth a thousand expert opinions”
It is great to see you back and blogging again on WUWT Dr. Svalgaard. You have been missed.
I, personally, have been gone for about a month. Moving to Alaska is not an easy feat. And so much has happened during my move. Climategate, Copenhagen, Colder temperatures. It will take me at least a week to catch up on all the posts since Thanksgiving.
But, with all that said, my passion still lies in heliophysics. The foundation to understanding terrestrial climate lies in understanding space weather. We will not be any closer to predicting climate here on earth until we have a better grasp on the study of heliophysics. I believe that.
Try to imagine having a sound card, a video card, a memory chip and processor, but not having a motherboard. Until we solve the basic concepts of space weather, PDOs, El Ninos and any other of earths anomalies will remain a mystery.
This post alone is evidence how little is known about space weather. Or more importantly, sifting through posts to understand real factual science, sidestepping the pseudo-science bloggers that wish to muddy the science of heliophysics, has become quite a feat in and of itself.
So once again, it’s a pleasure to see you back Leif.
Otherwise, I’m afraid people would fall into some trap, thinking that cosmic clouds in the local bubble are hell bent on destroying us.
Had to be said. Sorry.
We gonna need a star tax out there to combat the number of stars. They stars will kill us all! We need to prevent the number of stars in the galaxy from exceeding…
Lets just enjoy a nearer body tonight and enjoy a Blue Moon 🙂
toyotawhizguy (05:17:57) : I tried to find an absolute pressure for the vacuum of space. I would assume it is a lot less than 100 millitorr. I did find that rather than use pressure, it is allegedly too vague at the pressures and temps of space, that they use a count of particles per cm^3. While your temp may be similar, I would assume pressure is higher, therefore density/optical distortion is higher.
What interests me about globular clusters is why they don’t collapse into a single gigantic star/supernova. Are they orbiting a mutual centre of gravity?
“I wonder what the sky would look like from a world in the center of that cluster?”
Isaac Asimov’s best short story,”Nightfall”, was based entirely on that question.
Just a couple of speculative questions for those who understand the universe:
1) What happened before the Big Bang, or was it always a steady state?
2) If the universe is infinite, how can infinity expand on itself?
Take infinity to mean that time and space has no beginning or end, or in the case of time, there is not a moment that did not precede another moment
Robert Wykoff (22:52:48) :
> Obviously there are alot [a lot] of them way closer to each other than that.
Look at a photo of Andromeda or some other spiral galaxy. See all the stars packed into the arms? We’re in something very much like that The stars you see are all close to us in the arm. The rest of the galaxy is the Milky Way and can’t compete with street lights on Earth.
I’ve long wondered what the night sky looks like to an owl. BTW, in unforested areas star light is adequate for walking. I once made it from the Phantom Ranch to the “unapproved” campsite we had on the Colorado River in the Grand Canyon. We couldn’t use lights because the ranger because the ranger might catch us.
On the other hand, I ran out of daylight in the White Mountains in New Hampshire once. The key ring LED flashlight I had saved us from needing a rescue. Incredibly bad planning on my part. (The timing, not the light.)
Mick (22:44:07) :
E.M.Smith (22:45:04) :
A cluster may have it’s advantages, as shorter distances
which would allow interstellar travel or at least some emigration by “slowtrain”, generational, sub-light spaceships.
But it has it’s lacks, too:
Supernovaes may be more often, thus the chance for civilisations
to be wiped out by that is much higher than in our,
much more – rural – part of the galaxy.
More, the heavy elements are not evenly distributed over the galaxy.
There are not everywhere enough to support live and civilisations.
Last: The capability to build generational spaceships depends not
only on technical factors. Economic and sociological factors
may weigh more heavy.
Generally, we have most of the technology to build a
rather primitive spaceship, which may have a speed
of light/0.01.
To survive out there we need at least 20,000 people aboard.
So the spaceship as to have at least a volume of 2 to 3 million
cubic yards.
Now, to build it, my assumption is:
At least 50 years time from start to completion.
Approx. 1 million scientists, engineers and technicians may be
necessary for the whole project.
Approx. 3 to 5 percent of global GNP (gross national product) as costs.
At least 25 years as refresh/recreation time for the global economy
between each build.
For the people remaining on earth,
there will be no return on investment on all that.
So, for how long the populace will support the project?
My personal rule of thumb for it: No civilisation will support
more than three builds, because the people most eager to support
are from the same type as the people who like to be aboard.
(well educated, optimistic, and to them, chance has more meaning than danger. The pool of that type of people is always limited.)
IMHO there is a chance of 1/3trd, that any spaceship will successfully
reach its destination. More, I think it’s only a chance of 1/10th, that
that it’s big crew will successfully survive on a new planet and create a new civilisation.
More, with sub-light spaceships, distances of more than 50 lightyears
have to much constraints. So, even by consecutive successes, you are
always bound to your local part of the galaxy, there is no chance to successfully travel the empty distances between the spiral arms of the galaxy.
Nevertheless, sooner or later we will need to try space travel that way.
Simply, to not to have all eggs in one basket (earth, solar system).
Oh dear, with a 25″ there is not much you can hide! However, as I am using eye-glasses, I tend to use a b/w CCD camera (or webcam) instead of an eye-piece. I am a ‘proud owner’ of a C8 and a 60mm Takahashi apo refractor. The M13 image I linked to was using the Tak, small apertures can also be useful!
And yes, getting the image stretch right is always a balancing act….
The last couple of years have been terrible for amateur astronomers over here. From the outset, at 60N the summer is always too bright and the winter too cloudy. These days (nights!) the skies are full of ice crystals reflecting light & destroying contrast, if we ignore the fact that it is -20C. But the spring and autumn have usually brought some opportunities. However the last few years have brought ‘wall-to-wall’ clouds like I cannot remember seeing before. I secretly call them Svensmark clouds.
“Actually… that’s 1 star per 17.7 *cubic* light years, making it some 3.2ly on average between stars, assuming an even distribution. Of course, the distribution is not even, but denser towards the middle of the cluster.”
Excellent point, Gabriel.
Although I’m not sure how you got that number.
My first idea was that every star was at the center of its own little sphere. Using that assumption, I did the following math:
Find the radius of that little sphere:
r = (3/4 * 1/pi * vol)^1/3
so, in this case,
r = ((3*17.7)/(4*3.14159) )^1/3
r = 1.41 ly
so the distance (on average) between two stars should be
2 * 1.41 ly = 2.82 ly (i.e. from the center of one sphere to the edge, and then from the edge of the opposite sphere it touches to the center of that sphere)
But then I realized this was a problem because there would be a lot of unaccounted for space between the spheres (since they don’t pack into a solid) and therefore the number I got wasn’t really reliable.
So, then I was thinking that I should put each star at the center of a little cube because they would pack into a solid and would approximate the little sphere in concept. The length of one side of that cube would be:
s = 17.7^1/3
s = 5.9 ly
Meaning, on average, the distance to the next closet stars, at least in the six primary directions toward the faces of the cube, would be 5.9ly (half of the starting cube plus half of the destination cube).
But other stars are at different angles so I don’t know how well my approximation holds up.
Is there an accepted formula or concept for making this calculation?