Saturday, February 8, 2014

Star Parties and Presentations

I speak little of my presentations to schools. This lack of sharing is a combination of time and modesty. After each show, my free time is usually devoted to the next show, and as for modesty, I assume my observations are too amateur to put on public display. However, I thought I'd share some of the pleasure of presenting on astronomy to groups of children and their parents who comprise our typical star party audience.

I have an eclectic astronomy show that I keep on my website here: general astronomy show

The show includes my illustrations, animations, photos, and the photos of fellow members of the Temecula Valley Astronomers. It contains snippets from other shows I have online (Exoplanets, Earth, Orbit and Climate) plus from a few I've not found to time to publish. My show has diverse topics, allowing me to adapt to the interests of the students.

One common theme that I present is is parhelia. Parhelia is atmospheric phenomena caused by water and ice and sunlight. --not really astronomy, but it is easily observed and interesting to people of all ages. Most recently, I included rainbows by sharing diagrams of how the shape of rainbows change based on the height of the sun. I followed this with pictures of rainbows and asked the students to say whether the sun was high or low when each photo was taken.

From rainbows, I show various arcs and sundogs. This picture, taken by Temecula Valley Astronomer Mike Halderman, presents many different parhelia, and so I ask students to hold up a  finger count of parhelia effects they see:

Not counting any feature twice, the highest count included 1) the halo, 2) the sundogs, 3) the tangential arcs extending right and left from the top, 4) the arcs at the top middle, and 5) the corona effect around the sun. Technically, 3 and 4 are connected, but I've seen each by themselves.

After the wonders of arcs, sundogs, and such, I show a mystery phenomenon, a circum-zenithal arc --bottom left in this collection:

I ask them to compare it to the sundog (top left) and they notice the orientation of the color bands is vertical in one and horizontal in the other. We compare it to the various tangential arcs and the halo. Many thought, and correctly so, that you couldn't rule out the bottom of a halo, but the orientations of color bands are different.

In this picture of a circum-zenithal arc, I invite all the students to crane their necks high to show where one would have to be looking to see such an arc.

At the end of the parhelia, I share these two photos and tell them that they have a lot in common, which we explore when we cover the moon and the lunar eclipse:

The color of the moon during a lunar eclipse is caused by the same effect that colors the sky at sunrise and sunset. But, the photo of the sunset above includes a sun pillar, a column of light that is bent around the horizon. The sun pillar picture shows two phenomena: 1, that the atmosphere can filter out the blue light, leaving mostly the red, and 2, that the light is literally bent by the atmosphere, as that is what produces the column.

From this point I bounce around other topics, showing constellations, the solar system, the moon, and the eclipse, and some newly discovered exoplanet systems. One comparison I'm proud of is that since creating my exoplanets show several years ago, I've been sharing this with the students:

I tell them that when I was their age, we know of only 9 planets. But since 1993, over 800 have been confirmed around other stars, and that by the time they are in college, they may be doing the analysis that identifies what these planets are made of based on how their atmospheres affect the light from their stars (as we showed with the parhelia). 
So, for several years, I've been implying that these students are "generation exoplanet" as recently coined by NASA's spokesman, Neil deGrasse Tyson:


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