Category Archives: galaxies

astronomy, astronomy news, european southern observatory, galaxies, galaxy shapes, starbirth

Sculpting a Galaxy

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in Sculptor

Wow!  Take a look at this beauty of an image from the European Southern Observatory’s VISTA telescope.

ESO VISTA's view of the galaxy NGC 253, which lies about 13 million light-years from Earth. Click to massively galacticate. Courtesy ESO/J. Emerson/VISTA. Acknowledgment: Cambridge Astronomical Survey Unit.

What you’re seeing here is a VISTA view of the galaxy NGC 253, a.k.a. the Sculptor Galaxy, found in the constellation Sculptor (visible in Southern Hemisphere skies).  VISTA looked at this galaxy in infrared light, which gave it a great view of the rich collection of dust clouds that thread through the spiral arms of the galaxy. These dust clouds are where star formation takes place.  In fact, NGC 253 is a starburst galaxy, one that has undergone waves of star formation.  Tracing the dust clouds and bursts of starbirth allows astronomers to understand the formation history of the galaxy and the actions that have shaped it into the barred spiral we see today.

The telescope also was able to see a population of cool, red stars that aren’t very visible (if at all) in optical wavelengths of light (which are the main wavelengths our eyes can see).    This is what infrared viewing allows astronomers to do — that is, to peer through the veils of dust that hide the details of the Sculptor Galaxy. Now they can study in deeper detail the myriad of cool red giant stars in the halo that surrounds the galaxy, and measure the composition of some of NGC 253’s small dwarf satellite galaxies. And, they can search for new objects such as globular clusters and ultra-compact dwarf galaxies that would otherwise be invisible without the deep VISTA infrared images.

I remember some years ago when we first started seeing boasts by ground-based observatories that, using new (at the time) technologies such as adaptive optics, astronomers would be able to achieve “near-Hubble” quality observations of such things as the Sculptor Galaxy.  Images like this, from a ground-based observatory in Chile, show that it can be done.  And, the exciting part is that using observatories like this and the newly improved Hubble Space Telescope, our view of the cosmos is only going to get better!

astronomy, galaxies, hubble space telescope, musings

Billions and Billions of….

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Stars in Billions and Billions of Galaxies

Take a good look at this picture.  Go ahead, embiggen it. Check it out. I’ll wait.

A view of 12 billion years of cosmic history -- courtesy the Hubble Space Telescope.

What you’re looking at are galaxies. There are 7,500 of them in this image, which covers a very small angular area of space. The most distant galaxies lie more than 13 billion light-years away. That means the light captured in this image of those galaxies was shining a few hundred million years AFTER the Big Bang — the event that resulted in the birth of the universe.  The closest galaxies in this image emitted their light about a billion years ago.

When you look at this image, you’re gazing at a slice of cosmic time, a snapshot of galaxies in nearly every stage of formation and evolution.  If you looked in every direction, across the entire sky, the view would be similar to this — galaxies as far as we can detect. Billions and billions of galaxies, each one comprised of anywhere from a few hundred million stars to hundreds of billions of stars.

Think about that as you gaze at this picture.

That’s a lot of stars.  And, you have to wonder if we really are the only ones out here in this vast cosmos to appreciate that fact.  Are we the only life capable of looking up and wondering if any of those other stars have planets and life? I often think about that concept — as I  wonder what the future of the cosmos will be; and think about the glories of past histories in other galaxies — glories we can only appreciate as a dim glow from a galaxy long, long ago and far, far away.