Astronomers love to give evocative names to the objects they observe. That’s why we hear about things like the Ring Nebula and the Cat’s-Eye Nebula. Sure, the things they describe look like the name, although the monickers don’t always have much to do with the intrinsic nature of the object.
I recently ran across a really exciting-looking image of a bubble of gas being blown out by a Wolf-Rayet star. WRs are extremely hot (25,000-50,000 K), energetic stars that blast their outer layers away at thousands and thousands of miles per second. incredibly hot (25,000-50,000K) and expel their outer layers of gas at tremendous velocities (thousands of kilometers per second). It’s about 15,000 light-years away in the direction of the constellation Canis Major (the Big Dog). But, because it’s so bright and energetic, we can see it very nicely.
I haven’t talked about skygazing in a while. One of the exhibits I’m working on for the Griffith Observatory project explains how and why the rise and set positions of the Sun appear to change over the course of a year. It’s a migration that happens because of a confluence of the Earth’s tilt and its path around the Sun throughout a year. Many people think that the standing stones at Stonehenge and other places like the Cahokia Woodhenge and the Medicine Wheel in Wyoming are related to rise and set positions of the sun and stars throughout the year. They are almost like three-dimensional calendars in that way.
You can see this phenomenon for yourself if you go out each day and mark the rising and setting position of the Sun and stars along the horizon. As time passes, you’ll notice them shifting north and south along the horizon. If you watch long enough, you’ll see it repeat over the course of a couple of years—enough to make a predictable statement about where the Sun and stars will rise at a given time over the horizon.
“But I live in the city!” you say, noting that this can’t be done as easily from the middle of tall buildings. Yes, that may be true some of the time, but it CAN be done. As proof, I offer you a picture sent to me by my good friend Wendy Carlos. She made it from a composite of three images taken this past week in New York City, at the corner of 23rd and Fifth Avenues, near Union Square. It shows the alignment of sunset that occurs when the Sun’s rise and set path along the horizons east and west of Manhattan happen to correspond with an east-west cross street (and it’s worth noting that the cross streets don’t go exactly east and west). Exact alignments like this occur around June 28 and July 12 each year.
So, even if you live in the middle of a city, and you’re an astute observer, you CAN notice things in the sky!
