The Unidentified Crashing Object colliding with our galaxy is called Smith's Cloud, and is a cloud of hydrogen discovered last year. At the time, scientists believed it had a mass of a million suns, but it's been theorized that it would have to be much larger to have enough gravity to survive the impact. University of Sydney, Australia's Matthew Nichols and Joss Bland-Hawthorn have calculated that Smith's Cloud may, in fact, be up to 100 times larger than originally estimated.

Before you get too worried about the end of all known existence - or, at least, a Crisis On Infinite Earths - take some comfort in the knowledge that, if theories are correct, this has all happened before; according to the trajectory of Smith's Cloud, it would have impacted the Milky Way 70 million years ago. And it's not like anything has changed since then, right? Well, nothing important.

Dark galaxy crashing into the Milky Way [New Scientist]

Attack on the V838 Energy Collectors
Black Eye Galaxy
Cone Nebula
Crab Nebula
Milky Way
Orion Nebula
Phobos
Reflection Nebula
Starburst Galaxy
Butterfly Nebula

Here is a touched-up version of the same galaxy so that the tendrils are more obvious. The image you saw on top shows what would be visible to the naked eye, which is pretty damn cool. So what's this galaxy all about? Explains Phil "Bad Astronomer" Plait:

These tendrils have been a problem for astronomers: they’re very narrow (only a couple of hundred light years wide), have masses a million of times that of the Sun, and should fall apart rapidly (they’re blasting out into hot gas which should disrupt them, they’re massive enough to collapse under their own weight to form stars, and tides from the galaxy itself should shred them). Yet they seem at least semi-stable, lasting for hundreds of millions of years. What holds them together?

Turns out it’s that old standby, magnetism. Recently released Hubble images (like the one above) have given astronomers insight into the structure of these tendrils. Hubble’s hi-res view shows details previously unseen in the tendrils, allowing astronomers a better view and the ability to determine the magnetic strengths needed to hold the tendrils together against the forces that would rend them asunder.

In case you weren't already convinced that this was Cthulhu's home galaxy, that freakish and inexplicable persistence of the tentacles in the face of massive force should confirm it.

R'lyeh! R'lyeh! Actually, come to think of it, R'lyeh would make a great name for this galaxy, don't you think?

The Magnetic Tendrils of NGC 1275 [Bad Astronomy]

Lineweaver's four main preconditions for a piece of galactic real estate being hospitable to intelligent life are:

- Distance from galactic center. Our sun is about 8.5 kiloparsecs from the center of the Milky Way which is about right. The further you go out from the center of a galaxy, the fewer stars there are. The further you go in, the more likely a nearby star will go supernova, and wipe out life in your start system. LIneweaver figures between 7 and 9 kpc is about right.

- Age. Life takes time to evolve into something resembling intelligent. This takes a few billion years.

- Metallicity. This is Lineweaver's way of measuring how much of the supernova leftovers are accumulated in a given region of space. If there's less than 1% of the metals found in our solar system, there's probably not enough to build a rocky planet (in astronomers' parlance, 'metals' includes everything that's not hydrogen and helium, so stuff, like water, too).

- The likelihood of forming a gas giant. Like supernovas, Jupiters, Saturns and other giant planets make bad neighbors for harboring life. During the early stages of star system formation, they have a tendency to come crashing through planetary habitable zones, annihilating rocky planets that may one day harbor life.

In short, it's a galactic jungle out there, and in 2004 Lineweaver's beginning to get his head around narrowing down the best places we may find our interstellar neighbors, whether in this galaxy or the next. All that said, though, he's careful to point out that we don't even really know what a good definition of life is, so instead of "habitable zone" maybe the name should be changed to the more sensible (and way less-exciting) "pre-habitable zone."

Image: NASA

Chart: Science