Category Archives: musings

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.

hubble space telescope, musings

The Passage of Time

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Hubble Space Telescope

A model of the Hubble Space Telescope at the National Air and Space Museum in Washington, D.C. Click to enlarge.

I had a chance to go to the National Air and Space Museum for the AAS banquet last night. Before dinner, we had a chance to wander around and look at the exhibits in the museum.

As usual, I gravitated to the Hubble Space Telescope model and the exhibit that features its back-up mirror and a special presentation of the Wide Field Planetary Camera 2 that is on temporary loan to the museum. I had a nice long time to stand there and contemplate the telescope that was a large part of my graduate school experience — and, of course, my writing experience.  Back in graduate school I worked as one member of a large team that supported and used one of the original instruments on the telescope — the Goddard High Resolution Spectrograph. This instrument used the telescope to study objects in the universe in ultraviolet light. It was eventually removed from the telescope, but while it was deployed, GHRS turned out some seminal science.

When I decided to write Hubble Vision (my first major science book, with co-author Jack Brandt) and also the planetarium show that is showing in facilities around the world, it was clear to me that I needed to show people that astronomy is a multi-wavelength endeavor — and that most people don’t know that fact.  And, given the gorgeousity of HST’s optical images (and those from optical telescopes on the ground), that’s completely understandable.

These days, we are rather more used to seeing imagery created from observations in all wavelengths. People are more used to such visions, and that idea stimulated the book Visions of the Cosmos (that Jack and I also co-authored).  We enjoyed bringing a new vision of the universe to readers, and I think the days of knowing the cosmos only through the wavelengths our eyeballs can see are coming to an end.

Well, all these thoughts ran through my mind as I stood looking at the HST model last night. That telescope set me on a path that I could never have foreseen — an interesting and twisty path, but an ultimately rewarding one. Those thoughts — and memories of the early days of HST, the problems, the triumphs, the team meetings, the work we did — all seemed, paradoxically fresh — and old — at the same time.   One of these days, I’ll go to NASM and maybe our instrument will be an exhibit. I’ll feel really old, but it will also be a testament to the work that thousands of people did for many years to bring another vision of the cosmos to our senses.