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"Pandora's Cluster" --The Most Colossal Known Galactic Collision



This is the most colossal known smash-up observed in the universe. This awesome bundle of galaxies, nicknamed Pandora's cluster, turns out to be the result of a violent mashup between at least four separate galaxy clusters that occured over hundreds of millions of years. The cluster's official name is Abell 2744. Using various telescopes including NASA's Hubble Space Telescope and the European Southern Observatory's Very Large Telescope in Chile, astronomers have mapped all of its ingredients and pieced together its violent history.

The image suggests that several galaxy clusters have collided over about 350 million years, with visible galaxies making up 5 per cent of the mass, while searingly hot gas that glows in X-ray making up 20 per cent. The rest is the invisible x-factor, dark matter, the mysterious "X" force that  reveals itself only because its gravity bends light from background galaxies.

"The complicated and uneven distribution of the different types of matter is extremely unusual and fascinating," says Dan Coe from the Space Telescope Science Institute in Baltimore, Maryland, one of the study leaders.

The bright "bullet" near the cluster's core marks where gas from two clusters has collided to create a shock wave. Dense dark matter appears to congregate in one outer part of the cluster that's devoid of any galaxies or gas. Meanwhile, a lone ghostly gas clump has mysteriously detached itself and "sailed" ahead of its associated dark matter, a surprising observation that might clarify how dark matter and normal matter interact.

The Daily Galaxy via  NASA, ESA, ESO, CXC & D. Coe (STScI)/J. Merten (Heidelberg/Bologna)


We are always told that since the big bang expansion all galaxies are moving away from each other , a balloon blowing up with galaxies on the outside is often quoted as an example , so how do 4 separate galaxy clusters collide ?

Reading about other novas with 'knots' makes me think this is something like that. Wouldn't that imply that this smooth expansion has more to do with magnetism and electricity than some ill-named dark matter.

M, The expansion of the universe is occurring, but local gravitational effects and movement of galaxies in proximity to one another 'swamp' the effects of the expansion. At greater distances, however, the expansion overrides everything else.

The balloon analogy is a two-dimensional picture of what is happening in three dimensions. However, in the balloon example, the 'dots' on the balloon are fixed in position on the 'surface' of the balloon. In space, galaxies are not fixed.

How come gases/fluids in the form of seawater/clouds for example're able to negotiate each other's presences and interpenetrate or/and circumnavigate each other to form things like El Nino.

Ditto interacting electromagnetisms/plasmas can form things like double layers.

And even interacting gravities're capable of forming regions and layers hence Lagrange points.

But galaxies supposedly smash into each other like pile ups of overloaded hgvs on ill designed motorways?

Beautiful picture. The violet indicates that good things are about to happen.

If you keep pouring water into a pond and thereby expand its space, there's gonna be elements inside of it, which will unadvoidably collide.

M - I have been thinking the same thing myself for years now. I've never really had the opportunity to ask the right person for an answer. I hope someone replies with an adequate answer.

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