In 2001 we went on a cruise around South America and I was the ship’s astronomy lecturer. My job was to help the paying passengers do some stargazing and give them some fun lectures about the stars. It was great fun, and I had a marvelous time getting to know the Southern Hemisphere skies along with my shipmates. One of our favorite areas to look was the constellation Carina, which harbors the great luminous blue variable Eta Carinae. This (probable) double star system is on the verge of tearing itself apart, and when it does the view should be spectacular.
The Nebula itself is made up of cast-off material from the star system, and there is evidence of star-forming activity inside the clouds. So, the whole area is being watched with great interest by those who want to understand the mechanics of starbirth and stardeath.
Of course we couldn’t see any of this from the ship — our view was “limited” to the gaspingly beautiful southern Milky Way and the Magellanic Clouds and all the other sights we don’t get much chance to see from the Northern Hemisphere. The sky is just full of great stuff to study, and if you travel a lot, it enhances your visits to other lands.
I just finished work on a planetarium show about Hubble Space Telescope discoveries. I’ve written other shows about HST before, and this is sort of the “latest and greatest” one, and one where I really don’t know the ending. We’ve all been talking about the last HST servicing mission being cancelled, thus sentencing HST to its fate a few years earlier than everybody expected. Now it appears that Congress really does have the last say about this, and several folks have called for a re-investigation of the decision. So, the story’s not over yet. And, up there in orbit around Earth, HST continues on its merry way, sending back great images and science data (not mutually exclusive) for all of us to study and enjoy.
Well, rather than focus on the political aspects of HST’s “human side,” I spend all my time in this planetarium show talking about the great science it has done. It’s not an easy task. There’s a LOT to talk about, and a lot more to come. In fact, the most difficult thing about an HST planetarium show is choosing what NOT to show. There’s only so much time in the program, and in most planetaria, there are only so many slides one can cycle through in the course of a show. Sure we can throw in some video, for those who HAVE video projection capability, but for those who don’t, we’re kind of limited by the slides. I’ve chosen nearly 200 really great images and told a story of cosmic exploration using them as illustration. As I spend time looking at the sights that HST has seen for us, I’m impressed again with just how marvelous this machine has been. And what a wonderful time the astronomers who use it must be having when they open their data sets. Are they like kids opening presents? I like to think so. Or at least HOPE so.
The Eskimo Nebula (planetary nebula)
One of the images I’ll be using in the show is a study of a planetary nebula that lies about 5,000 light-years away from Earth. It’s called “The Eskimo” Nebula because it looks like an intricate furry hood that an Eskimo might wear. The “parka” is really a disk of material surrounding a dying, Sun-like star. Inside the cloud is a ring of comet-shaped objects, with their tails streaming away from the central, dying star. The “face” consists of a bubble of material being blown into space by the central star’s intense “wind” of high-speed material. The story behind this apparition is fascinating. The star that formed this cloud began to lost much of its mass to space about 10,000 years ago. Before that time it had gone through what’s called the “red giant” phase, breathing out a ring of dense material that collected around the star. That ring is actually moving out from the star at about 115,000 kilometers per hour. Hot on its heels (so to speak) are high-velocity stellar winds, moving out from the star at 1.5 million kilometer per hour. They are shoving material above and below the star, creating elongated bubbles. Each bubble is about one light-year long and about half a light-year wide.
This is just one of a dozen or so planetary nebulae I’m presenting in my show, and while I can’t talk about them in excruciating detail, I can at least show people just what our Sun might look like in 5 or 6 billion years when it starts down the path toward planetary nebula-hood. Fun stuff!
