Star and dust clouds

We have all seen many types of clouds. Rain clouds, puffy white clouds, clouds with rainbows, even clouds of gnats and clouds of steam from an old fashioned locomotive that i saw when I was a child.

Have you ever seen a cloud of stars? I – in summer Milky Way.

Our galaxy is a spiral galaxy about 120,000 light years across – more or less – it’s hard to measure a galaxy you’re in.

All spiral galaxies are “dirty”. That is to say, they contain a large amount of dust and gas which is nothing but dust and gas. Sometimes the patches of dust are so black and dense that they can block the stars behind them, just as the Moon can be hidden by thick clouds.

Good photography of the Milky Way became possible at the turn of the 19th and 20th centuries. When scientists started photographing our galaxy, they noticed large dark spots that, in places, were very black. A controversy has erupted over the nature of these black spots. Two ideas clashed. The first thought was that these dark spots were places where stars just didn’t form. However, no one could imagine why stars weren’t forming in these black spaces when huge numbers of them were forming right next to the black spots. A second idea was that the dark places were formed by huge patches of dense dust and gas and that these blocked astronomers from seeing the stars behind them.

A very great American astronomer, EE Barnard, essentially self-taught, speculated on the dark spots and proposed that the dark spots were clouds of dense, black dust. Using a 10-inch camera and the fastest film, Barnard took images of many of these “dark nebulae” and published several copies of his actual photographic prints bound as a book. (An original copy of Barnard’s work is quite rare – and valuable.)

Those scientists, including Barnard, who thought the dark spots were clouds of dust that hid the stars behind them, were right. Obscuring nebulae appear to be present in all the spiral galaxies that we can currently photograph.

So there are the clouds that we see during the day, in our atmosphere, and there are the clouds of stars and dust that we can see with a telescope or photograph with a camera.

I’ve included an image of a star cloud that I made with a very fast telephoto lens. This cloud of stars has a name: the Scutum Star Cloud. He is often photographed by amateurs because of his mysterious beauty. There are hundreds of thousands of stars in this image, forming the cloud. Intertwined among these stars are lines and specks of obscuring dust.

If you go to bed late, you can see Saturn rising in the southeast. Standing until about midnight, Jupiter can be seen, just on the eastern horizon. Throughout the year, these two planets, as well as Mars, can be seen in the mid-evening.

At a dark vantage point, look for the Milky Way, almost overhead. Get out those binoculars and see if you can see star clouds – and dark clouds too.

Don’t miss the Perseid meteor shower on the night of August 12-13. All you need is to go to bed late and use only your eyes.

— Dr. David Cater is a former JBU faculty member. Email him at [email protected] The opinions expressed are those of the author.

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