Galaxy Discovery

Excerpts from my journal of Friday, May 26, 2006, about an astronomy trip to the western Utah desert:

“Last night was the best I ever had with a telescope. All my equipment performed wonderfully … the telescope was tracking so well that I just went ahead and took photos without a guider. Exposures of a minute were fine, and I used the track and accumulate feature to make exposures of two and three minutes for each of the three colors.

“I started with M65, moved on to M66, then had the surprise of my astronomical experience, M101. I didn’t know what it looked like and had never seen it before. The telescope was focused nicely from my using it with M66, and when I used the ‘go to’ instruction to find M101, I couldn’t see it through the finder scope. The galaxy is relatively dim. I had the CCD camera attached to the telescope so had to locate it through the guide [I meant finder] scope. At last thought I saw some dim thing a short distance from the crosshairs, and I moved the telescope to that point, then downloaded a one-minute exposure. I was stunned to see the lovely spiral galaxy show up on my computer screen, though it was off-center. I was able to center it, then took a series of pictures. The galaxy is my new favorite, as it’s so lovely, spangled, sprawling, studded with clumps and clusters of luminosity, with arms something like a starfish if one were to curve its arms. …

[Galaxy Messier 101, in my photograph from 2006]

“Another treat were the occasional coyote concerts, with yipping, yodeling and howling. A dog was barking along, possibly a feral one that had joined the pack. There was no moon to howl at and I can’t imagine why they would suddenly break into song but I enjoyed it. The first time it happened I tried to find my cell phone and call Cory, but I couldn’t locate it quickly enough in the dark; cell coverage was awful, but I wanted to give it a try. Then they stopped and other yodels were too late to be calling.”

Messier 101 is often called the Pinwheel Galaxy, for obvious reasons. About 25 million light-years away in Ursa Major, the constellation that includes the Big Dipper, it is an estimated 170,000 light-years across. The dramatic lumpy regions are star-forming patches, something like the Orion Nebula. Three supernovae have been seen in the galaxy, which is twice as big as our Milky Way Galaxy.

The European Space Agency posted a note on the Internet recently saying M101 has about 1 trillion stars. According to the ESA, many “hot spots” where stars are forming are located along the outer edge. “This is unusual because star formation is generally active in the central parts of spiral galaxies,” the agency adds.

“The evidence points to M101 having experienced a close encounter with a companion galaxy in the past, dragging out gas from the hapless companion. The gas is now falling onto the outer edge of M101 at approximately 150 km/s, triggering the active star formation.”

Considered the finest nearby spiral galaxy, M101 is so beautiful that when NASA gave several institutions displays of astronomical photos last month, it was the subject. The displays were to mark the International Year of Astronomy and the 400th anniversary of Galileo’s first telescopic observations. One of these went to Weber State University, Ogden, where it was to be showcased permanently at the university’s science museum.

Pierre Mechain discovered M101 on March 27, 1781. But it is a wonderful discovery for every astronomer who glimpses it for the first time. For about an hour on the night of May 25-26, 2006, I was Mechain in 1781.

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