HIKING THROUGH THE SOLAR SYSTEM


The Obsidians are a hiking club in Eugene sponsoring hikes, climbs, bike trips, snowshoe and cross-country trips, bus trips to distant parks, a summer camp with a week of day hikes and catered meals, and … in town hikes.

I took my first hike with the club about a month after I arrived, after 3 hikes qualifying for membership.  One of the officers wanted me to lead hikes right away, but I insisted I had to know a trail before I organized and took people to an area.  Three months after a summer of exploring  the central Cascade foothills, scores of hikes, I led my first one.

My twenty-eighth hike as a leader wasn’t to Collier Cone, Obsidian Loop, Larison Rock, or Browder Ridge.  It was a hike in town, walking the one to one billion scale model of the solar system.  I got the idea one day while strolling through Alton Baker Park, where the Sun, a 4 foot high model, stood.  Why not do a 7.5 mile hike through the scale model of the solar system?

And so, on a chilly New Years’ Eve Day morning, a dozen people who had signed up for the hike and I began our walk near the duck ponds at the western edge of the park, near the Willamette River.  I had reviewed the facts about the planets: size, day length, orbital period, presence/absence of a magnetic field, temperature, but when I reached the Mars post, the first stop, I put the notes away. I wasn’t sure what I would do, but I wasn’t going to recite facts.

We began at Mars, not Mercury, because the post was nearest where we parked, I wanted to have the hike move in more or less a straight line, and we were parked closest to Mars.

I quickly realized I was at a daylight star party, except the stars were planets, and I didn’t have a telescope.  Everything else was the same.  I was teaching to several interested adults near me.  Earth-Moon was second on the walk, and I discussed the size of the Earth, far smaller than a marble at this scale, and its 150 meter or nearly 500 foot distance from the Sun.  I showed the vast emptiness of the solar system, how far we were from Mars, and how little was in our neighborhood.

Mercury has the day where the Sun rises, gets high in the sky and then sets.  Really must be something to see.  I mentioned while many thought Mercury was difficult to see, there are times it is easy.  Indeed, I saw it from downtown Chicago one night years ago.

I remembered  that Venus has no magnetic field but instead spoke of the resonance between 5 passages of Venus by Earth, 584 days apart, and how that time is almost exactly 8 Earth years.  I told them of the transits of Venus I observed in 2004 and 2012.  I said transits were so rare that in 2012 the grandchildren of a newborn baby, whose mother held him up to the eyepiece, might see the next one if they lived long enough.

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Transit of Venus, 5 June 2012

When we reached the yellow large ball that marked the Sun, I spoke of how the Sun generated heat through nuclear fusion, producing prodigious amounts of helium every second from fusing hydrogen, yet would still exist for many more billions of years. I talked about fusion of helium into other elements, all the way to iron, in larger stars, where fusion no longer gave off energy, and the star had a problem, because gravity pulling in and heat expanding no longer balanced each other.  The resulting collapse formed all the other elements; the presence of iron in our blood, magnesium in chlorophyll, silicon on the sand we walk on were all parts of nuclear fusion from a star that existed prior to our Sun.

We next crossed the Willamette and walked on the South Bank trail.  Shortly, we reached Jupiter, and I talked about the Galilean Moons, how I once saw them covered by the waning crescent Moon, reappearing one by one as the Moon slowly moved.  I told them about the dark spots caused by the collision of Shoemaker-Levy comet on Jupiter in 1994, and a time I saw Jupiter in daylight.  I forgot to mention the special night I saw Jupiter, a meteor and lightning flash all at the same time, 25 years ago.  When one observes the night sky, there are many such surprising gifts.

Saturn was a little more than a half mile further away. I mentioned the rings, how they could open up part way, viewed from Earth, but could also be edge-on.  I was asked if we could see the rings from directly over Saturn.  Sadly, we cannot.  Twenty years ago, I showed people Saturn with edge-on rings at a non-astronomy conference I attended at Palm Desert, California.  I spent three nights in a parking lot with my telescope, each night having more and more people, until the final night I had a steady line of 40 waiting patiently.  I don’t remember what I learned at the conference, but I never forgot the nights outside.  I suspect many of those who looked through the eyepiece felt the same way.

I also talked about the 28 Sagittarius-Saturn occultation in July 1989, when Saturn passed in front of the star, which appeared to move through the ringlets, only 20 meters wide, but each band clearly discernible as I watched Saturn move—yes, I saw it move—until the star was between Saturn and the innermost ring, a truly once in a lifetime sighting.  I was in my element now.  The temperature had risen, I was not lecturing but rather discussing how the planets affected my life, my observing, and were part of me.

Uranus rolls around the Sun, its axis directly pointing at the star.  I wore a button in 1986, 30 years ago, commemorating the arrival of Voyager 2 at the planet.  Voyager 2 took the Grand Tour, money well spent, NASA arguably at its best, as the craft used the planets as a slingshot, a close fly-by of Jupiter, using Jupiter’s gravity to go to Saturn, using another gravity assist to go to Uranus. I remember the ice rilles on Miranda, one of the moons, and the gas clouds of Uranus itself.

A mile later, we reached Neptune, 2.8 miles from the Sun, its 165 year orbit meaning it moved only 2 feet a day at this scale.  My memory was Neptune All Night, the show on a late August evening in 1989, when I observed Neptune while listening to the discussion of what was being sent back by the spacecraft.  Neptune had a big dark spot and rings.  I also remember the high winds reported on Neptune, the geysers on Triton, completely unexpected, the way all the visits to all the planets revealed the unexpected.

My hike through the solar system was not at all what I expected.  I hope to repeat it annually.

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