Saturday, August 31, 2013

4.6 Billion and Counting (presentation is online)

I just put my presentation on the Nice model of the solar system, 4.6 and Counting, on my website at

My presentation is primarily for my use in that I'm not trying to write out all the explanation I provide when I present it. Also, there are four interactive animations that lack instructions. Curious observers will have to make their own discoveries. However, I've provided a lot of illustrations with descriptions, so one may find it instructive. As always, I invite suggestions and corrections.

Notes on interactive illustrations:
"Exoplanets": I use an animation of the solar system to compare our solar system with two exoplanet systems. The exoplanet systems are examples of systems that would not have been created without significant planetary migration. Clicking a planet will scale the size to the clicked planet's orbit. For example, click Mercury at the bottom of the page, find the horizontal speed slider to slow down the movement, then click one of the planet check boxes near Mercury to see the orbits of a Kepler system.

"Resonance": I use this to illustrate how a 1:2 resonance can disturb the orbit of a planet. Click the "inner" check box and then watch what happens to the inner planet. I never finished this animation for the outer planet. My intention is to show how an eccentric orbit of a KBO object can be stabilized by a resonance with a planet like Neptune.

"Res2": Here I show that resonance can occur when one or two planets migrate. You can change the positions of the two planets to create a 1:2 or 2:3 resonance.

"Planet Toss": Press any key to move through this animation that shows the interaction between large planets and small planetesimals.

And all the other chapters have text at the bottom describing the pictures.


Sunday, August 25, 2013

Sun Pillar (almost)

On the way to the Lake Skinner star party, I saw a sun-pillar-like phenomenon. It's best described as a diffuse sun pillar:

You can see a shadow off of the mountain in the center. This shadow demonstrates that the sun is below the horizon and not behind the bright patch of cloud in the center. With the sun below the horizon, the bright patch is illuminated by light refracted, or bent, by ice crystals in the clouds. If the clouds were thinner, I suspect the pillar would have been more compact, appearing as a column, similar to this sun pillar I photographed a couple years ago:

The above sun pillar was photographed in January, the colder weather enhancing the ice crystal formation needed to create a well defined column. My hypothesis is that the same phenomena in summer tends toward more diffuse pillars, as shown by this sun pillar, which I also photographed during hot weather a few years ago:

In addition to a sun pillar,  I also saw a fireball meteor during last night's star party at Lake Skinner. In the south, a bright meteor, many times brighter than Venus glowed and crawled south and then broke up into at least three visible parts. I was not the only one who saw it.


Sunday, August 18, 2013

Public Star Part at Lake Skinner, Saturday, August 24, 2013. 8:00pm

Lake Skinner is hosting a star party on Saturday, August 24. The event is free and open to the public. Lake Skinner charges and entrance fee, but will waive it for people attending for the star party only. I'd recommend arriving between 7:30 and 8:00. At 8:15, there will be a brief show followed by star gazing, from 8:30- 9:30. The star party will be held at the amphitheatre, marked on the map below.

If the weather looks hazardous on Friday, check the Lake Skinner website (or Facebook page) to verify if the event is still being held: See

Saturday, August 17, 2013

Nova and the Dolphin

Amateur astronomers are glowing over the appearance of a nova that is visible to the naked eye. Though the nova is in the eastern sky in the evening, I waited till it was in the west to photograph it. The moon was just past first quarter and bright enough to interfere with photography, so I waited till 3:00 on Thurs morning (8/15/2013) when the moon had set. Below is an annotated photo of the region I took last year with my 8/15 nova photo superimposed. An arrow depicts the nova.

(Tap or double-click to enlarge)

I was going to create an animated version to fade between last year's and this year's photos but had trouble aligning the stars in the two photos. Though both photos were taken with a 28mm lens, last year's image put the region of interest at the edge of the field of view, where the lens's distortion is greatest. My nova photo was centered on the Delphinius, so the stars wouldn't align. However, I found the misalignment revealing. The nova is the only star in this composite that doesn't have the illustion of a motion blur.

All stars that are in both images appear in motion or blurred, but the nova lacks a blurry companion because it appears in only one image. Below is the same composite image with an arrow depicting the nova.

The nova should be viewable at next Saturday's free public star party at Lake Skinner. Details to follow.