Deep Space Inhabitants - Dark Matter

Credit: NASA/ESA/M.J. Jee and H. Ford (Johns Hopkins University)

Much like black holes, dark matter suffers from a lack of visibility. It may make up almost all of the mass in the universe, but it doesn't emit or reflect light or other forms of radiation.

So what is the evidence of its existence? Astronomers infer its presence from gravitational effects on visible matter. In the Hubble Space Telescope composite image above, you can see an ethereal ring of dark matter in a galaxy cluster. How is that possible? Light from more distant galaxies is bent by the galaxy cluster. By observing those distortions, astronomers can map them and determine how the dark matter is distributed.

Credit: NASA/ESA/C. Heymans (Univ. of British Columbia, Vancouver)/M. Gray (Univ. of Nottingham, U.K.)/M. Barden (Innsbruck), the STAGES collaboration, C. Wolf (Oxford Univ., U.K.)/K. Meisenheimer (Max-Planck Inst. for Astronomy, Heidelberg)/COMBO-17 collaboration

Another composite image shows clumps of dark matter around a galaxy supercluster.

There's got to be some frustration for astronomers in not being able to see most of the universe, of only being able to infer it. Then again, the vast majority of knowledge we receive is indirect. Any new item I read or view is inferred, in that I'm not there to witness the event. Even knowledge of other people is second-hand. We have to trust they're being honest when we ask what they're thinking or feeling.

The hardest thing to accept, though, is that even with ourselves, direct knowledge of the psyche is hard to come by. We have our habits and compulsions, our little ways, but self-knowledge is largely intimated, and true insight is rare.

But the night has not left us without resources. So I'll be turning my attention from the night sky and toward the inner landscape as revealed by our dreams. Stay tuned.

Deep Space Inhabitants - Black Holes Revisited

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A couple of weeks ago when I wrote about black holes, I neglected to mention what happens when things get sucked into a black hole. So here's author Neil deGrasse Tyson explaining that process to Jon Stewart in an interview from 2007. Tip of the night: Avoid black holes.

Deep Space Inhabitants - Black Holes

Credit: X-Ray: NASA/CXC/D.Hudson, T.Reiprich et al. (AIfA);
Radio: NRAO/VLA/NRL

The true magnitude of the weirdness of deep space becomes clear when you start to think about things like black holes. Most garden-variety black holes are remnants of supernova explosions that collapse in on themselves. They reach a point of zero volume and infinite density, from which no light can escape.

So how can there be pictures of black holes? It works if you can capture signals other than light. It also helps to target supermassive black holes, which are thought to exist at the centers of some galaxies.

The image above is a composite of x-ray and radio signals and reveals a binary black hole. According to the information on this image, these objects are "surrounded by multimillion degree x-ray emitting gas, and blasting out jets of relativistic particles."

Composite Image Credit: X-ray in red - NASA/CXC/S.Allen (Kavli Inst., Stanford) et al.;
Radio in blue - NRAO/G.Taylor (VLA);
Infrared in green - NASA/ESA/W.Harris (McMaster Univ.)

Another composite image, this one including infrared, shows material that fell towards a supermassive black hole, then was blasted back out. The blue regions are radio-emitting bubbles that measure about 10,000 light years across.

I like the idea of using different signals to image black holes. When one way of seeing fails, try another. The persistence of astronomers has revealed extraordinary processes where powerful energies swirl around regions of nothingness. These processes allow us to see the cosmic dance of creation and destruction that otherwise would have been hidden by the void of space and of the black holes themselves. Kind of makes me wonder what else we might be missing for fear of the dark...

Deep Space Inhabitants - Nebulae

Credit: NASA/ESA/HEIC/The Hubble Heritage Team (STScI/AURA)
Acknowledgment: R. Corradi (Isaac Newton Group of Telescopes, Spain), Z. Tsvetanov (NASA)

Deep space nebulae - the eye candy of astronomy. These clouds of space dust, plasma and hydrogen are some of the most beautiful objects in deep space. The image above is of the Cat's Eye nebula, which is actually a dying star. If you've noticed a similarity between it and Sauron's eye from the Lord of the Rings movies, you're not the first. It wasn't the only nebula I found that looked like an eye. I'll end this post with another one.

Credit: T.A.Rector (NOAO/AURA/NSF)/Hubble Heritage Team (STScI/AURA/NASA)

Perhaps more familiar is the Horsehead nebula in the constellation of Orion. I remember this nebula from school, so we've had pictures of it for a while. This one is from the Hubble Space Telescope, as are all the images here. It's a wonderful thing when science and art converge.

Credit: NASA/ESA/The Hubble Heritage
(STScI/AURA)-ESA/Hubble Collaboration
Acknowledgment: J. Hester (Arizona State University)

The delicate colors of the Veil nebula, above, are the remnants of a supernova explosion.

Credit: NASA/ESA/J. Hester and A. Loll (Arizona State University)

The same is true of the Crab nebula - it's also the remains of a supernova. Its blue glow comes from a neutron star at its center. According to the news release for this image, "The blue light comes from electrons whirling at nearly the speed of light around magnetic field lines from the neutron star. ... A neutron star is the crushed ultra-dense core of the exploded star."

Credit: NASA/ESA/J. Hester (Arizona State University)

Nebulae aren't always about star deaths. They can also be places of star formation. The Omega or Swan nebula, above, is a complex structure, with ultraviolet radiation interacting with hydrogen, oxygen and sulfur. The radiation is coming from young stars that aren't quite in the image.

Credit: NASA/ESA/M. Robberto (Space Telescope Science Institute/ESA)/
The Hubble Space Telescope Orion Treasury Project Team

Another region of star formation is the Orion nebula, only 1,500 light years from Earth. Thousands of stars are being born in this beautiful chaos.

Credit: NASA/H. Ford (JHU)/G. Illingworth (UCSC/LO)/M.Clampin (STScI)/
G. Hartig (STScI)/The ACS Science Team/ESA

Finally, we have one more image of the Omega or Swan nebula. This is the other eye I saw - notice the red half-circle to the right of and below center. Notice also the red arc to its right. Then imagine some reclining being and that's its eye, with a red eyebrow. Not as scary as Sauron, but still not someone I'd like to have an encounter with anytime soon. Nebulae are gorgeous, until you start finding stuff in them...

Deep Space Inhabitants - Galaxies

Credit: NASA/Hubble Heritage Team (STScI/AURA)

Heaven's net casts wide.
Though its meshes are coarse, nothing slips through. - Lao Tzu

While the various spacecraft have been flying through the solar system to bring us images of the planets, the Hubble Space Telescope has been quietly orbiting the Earth for 18 years, capturing extraordinary pictures of deep space, including gorgeous images of galaxies.

It's hard to believe, but it wasn't until the early 20th century that astronomers began to seriously think that what they had been calling "spiral nebulae" might actually be star systems beyond our own Milky Way galaxy. With advances in the optics of telescopes, it became clear that these nebulae were not new solar systems forming within the Milky Way, as was previously thought. As it stands now, astronomers calculate there are 100 billion galaxies in the universe; each contains between 10 million and a trillion stars.



Those are the kinds of numbers that make it hard for people to get their minds around astronomy, especially when it comes to extragalactic phenomena. This video tries to make the numbers easier to understand, and also explains two deep field images taken by Hubble. They revealed a surprising number of galaxies in two areas of the sky that were thought to be pretty empty. Whether they're among the most important images ever taken, as the video claims, I'll leave to your judgement. They certainly are amazing.

For more galaxy images, maybe to update your screen saver, check the Hubble gallery site. You can also find images of galaxy collisions that were recently released.

There's always a danger when discussing the vastness of the universe that a person might end up feeling insignificant, like a single grain of sand on a beach. But here's another perspective to consider, from writer Timothy Ferris:

The reassuring aspect of the portrait of the universe we now see drawn across the sky lies in its reconciliation of humanity with the material world. That we are part of the galaxy is literally true. The atoms of which we are formed were gathered together in the toilings of a galaxy; their fantastical assembly into living creatures was nourished by the warmth of a star in a galaxy; we look at the galaxies with a galaxy's eyes. To understand this is to give voice to the silent stars.