Change is the Only Constant

One of the interesting aspects (out of many) about my writing and research work on the exhibit project for Griffith Observatory is realizing (again) how quickly things change in astronomy. Just when I think I can say something with great certainty about a celestial object or process, a discovery comes along that shifts the landscape of “what is known.”

Take the announcement I got tonight about the discovery of what is likely the 10th planet in our solar system. Astronomers Mike Brown of California Institute of Technology, Chad Trujillo of Gemini Observatory in Hawaii, and David Rabinowitz of Yale University in Connecticut used the Samuel Oschin Telescope at Palomar Observatory to spot a Kuiper Belt object in the outer realms of the solar system that is definitely larger than Pluto (currently the 9th planet of the solar system). Now, anybody who’s had their ear to the ground lately has heard a number of conjectures about Pluto and the rest of the KBOs (as they’re called). Some folks think that Pluto is merely a planetoid, and doesn’t deserve the name “planet.” Others maintain Pluto’s a planet, and I count myself among them.

There is NO doubt, however, that there are large objects out in the Kuiper Belt, which is a region of space populated by objects like Pluto (some larger, some smaller), most of which date back to the earliest epochs of our solar system’s existence. Astronomers are actively searching out these objects and trying to understand them. By studying them, we may find out more about the composition of the cloud of gas and dust from which all the planets, moons, rings, asteroids, and comets formed more than four billion years ago.

So, does this change what I write for the exhibition about the Kuiper Belt, Pluto, and our solar system? An excellent question. I’m sure our discussions about this information will be interesting, indeed!

Sunrise, sunset…

Image of sunset in NYC

Image of sunset in NYC

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!