The planets that once were

The solar system is our home, our own comfortable little neighborhood of the galaxy, and as mankind has grown as a species and become more technologically capable, we have begun to venture forth into this neighborhood and to familiarize ourselves with it. The results are far more wondrous and varied than we could have imagined when all we knew of the cosmos was what we could see with our eyes only.

The planets that have been known of since antiquity are those that are easily visible with the naked eye – Mercury, Venus, Mars, Jupiter, and Saturn. Even before we knew of these things as astrophysical objects, they were seen as bright points of light that seemed to wander independently of the background of the stars. In the 1700s and 1800s the solar system became populated with more than just these familiar few, and as these discoveries were made it became clear that it was a more diverse place than we had suspected. As Uranus (1781) and Neptune (1846) were discovered, it was clear that these objects were of the same nature, albeit a little farther and a little dimmer. But the objects Ceres (1801) and Pluto (1930) were not so clearly determined.

Pluto and Ceres share common ground in that they both have introduced us to regions of our solar system populated by hundreds of thousands of objects: the asteroid belt in the case of Ceres, and the Kuiper belt in the case of Pluto. With these discoveries came the need to further consider the nature of these objects and the proper ways to categorize them. Ceres and Pluto trailblazed the identification of asteroids and dwarf planets, but for all the discussion they have introduced, we’ve never really gotten a good look at either one. Two recent missions have set out to correct this deficit and make us a little bit more familiar with some of the Earth’s diminutive cousins.

A size comparison of different solar system bodies. []

On January 1st, 1801, Giuseppe Piazzi discovered a new object orbiting at about 2.8 AU from the sun. Although it was difficult at first to ascertain the exact size of this object, dubbed Ceres, it was clear that it was not quite in the same category as the known planets. Therefore, the term ‘asteroid’ (‘star-like’) was coined. Nevertheless, some textbooks listed Ceres as a planet among the others, and continued to do so for a number of decades.

Soon after Ceres became known astronomers found other objects to populate the region of space between Mars and Jupiter, a region that has since become known as the asteroid belt. Ceres is often referred to as an asteroid, although the new designation ‘dwarf planet’ also applies.

On March 6th, 2015, the Dawn spacecraft ( arrived at Ceres. As it approached the asteroid, it was able to achieve stunning photos of this object, revealing a pock-marked face reminiscent of the lunar surface. Dawn continues to explore the surface and atmosphere of Ceres, revealing to us information about the formation and evolution of the solar system.

Images of Ceres as taken by the Hubble Space Telescope. []

Images of Ceres as taken by the Dawn mission on its approach to the asteroid. []

The discovery of Pluto, which took place in 1930, is much more recent, and has proved to be a bit more controversial. Many people are familiar with the discussion that took place a few years ago that resulted in the re-categorization of Pluto as a dwarf planet. Some took this hard, and consider this more of a demotion than a categorization. For the entirety of the twentieth century after its discovery, Pluto was considered the ninth planet. It was only as other objects began to be discovered in the same region of space, now referred to as the Kuiper belt, that the call for reclassification came.

The deciding moment came in 2005 when the object Eris was discovered and found to be roughly the same size as Pluto, though orbiting at a greater distance. Rather than considering Eris the tenth planet, and opening the way for some as yet unknown number of similar objects to become planets, the International Astronomical Union (IAU) decided to meet and formally consider the definition of ‘planet’. They settled on the following three properties:

  1. It must be in orbit around the sun.
  2. It must be massive enough for its gravity to pull it into an approximately spherical shape.
  3. It must have “cleared its neighborhood” of similarly sized objects and become the gravitationally dominant body.

Objects that meet the first of these two requirements, such as Pluto and Ceres, but fail the third are categorized as dwarf planets.

On July 14, 2015, the New Horizons spacecraft ( is expected to arrive at Pluto, achieving a fly-by distance of about 10,000 km. Due to the distance between the Earth and Pluto, it will have taken New Horizons over 9 years to reach its destination. When it arrives, it will be able to take images superior to those possible from Earth with even the most powerful telescopes.

Pluto and its moon Charon, as seen by the Hubble Space Telescope. []

For all the discussion of categorization, in the end, names are just names. A dwarf planet, by any other name, would orbit just as sweet, to butcher Shakespeare. Categorizations are a useful tool to help us understand Nature and its workings, but there will likely always be natural phenomena that defy these classifications, no matter carefully we define them. The important matter is not what we call something, but what new insights into the universe it has to offer.



Wanderers, a short film from digital artist Erik Wernquist, is an amazing visual exploration of what the future may hold for the human race. Wernquist provides digital reconstructions of what various places in the solar system might look like as they are explored and settled by people, and it’s all overlaid with the voice of Carl Sagan. It’s quite beautiful.

I am reminded of a quote from Joseph Conrad’s Heart of Darkness, in which the protagonist imagines what it would be like to have approached our own home planet as someplace new:

“We were wanderers on a prehistoric earth, on an earth that wore the aspect of an unknown planet.”

A brief interlude

Posting has been pretty non-existent over the last several months, and I suppose that requires some explanation. I am currently entering the last stages of my PhD program, and this, understandably, has been taking up much of my time. I hope not to drop this blog entirely, and I will try to find some things to say from time to time.

Technology will kill your brain

I’m quite interested in how new technologies change the way we think, and I often wonder which of these changes are desirable and which are not. All the same, when I found this article from Dean Burnett, I had to chuckle a bit. Burnett lays out for us once and for all how to write any article addressing the question of technology and the brain.

The article is concerned about the effects this new technology will have on the brain, so you will need to include a general explanation of the brain’s workings, particularly a feature of it that is somehow relevant to this new thing people should be scared of.



For example, if the new technology offers new types of visual stimulation, briefly describe the brain’s complex visual system. If it’s more language based, the language processing features of the brain can be discussed. It’s a big, complex organ, the brain; there’s probably some feature of it that seemingly supports your “concerns”, so don’t feel restricted.

3D printing a house

See Contour Crafting: Automated Construction (via Peak Energy)

Behrokh Khoshnevis, an engineering professor at the University of Southern California, is developing a scaled up version of 3D printing that he has dubbed ‘contour crafting’. He hopes that it may one day be able to alleviate housing shortages in the world due to its speed (he estimates that an entire house can be constructed in about 20 hours) and the reduced costs associated with its use.

This is a clear cut example of a solution that, as Khoshnevis says, “benefits from advanced technology”. It tackles the complicated problem of affordable and abundant housing head on, though it would appear to do nothing about addressing the larger problem of poverty. Opponents to the technological approach might argue that the real problem has to do with the structure of societal and financial systems. Though a cheap and sturdy home might be a step up from the slums, if the underlying problems of income inequality and resource allocation still remain, they will surface in other ways. One only needs to look towards housing projects in American cities and elsewhere to know that giving someone a roof over their head doesn’t necessarily free them from a life of poverty and crime.

Khoshnevis mentions another potential use, which is using contour crafting to construct buildings in situations where previous construction methods could not work (such as in building a moon base). This strikes me as a better use of the technology, since the problems it solves here are more straightforward and direct, rather than being simply one small subset of larger socio-economic issues.

See also:,

Nature and Technology – Wendell Berry’s Middle Ground

Wendell Berry, in his essay ‘Preserving Wildness’, defines his position on the issue of protecting ‘nature’ and ‘wilderness’. He views this problem as one which there is often a high degree of polarization between ‘nature extremists’ on the one hand, who see the natural operations of the environment as dominant over mankind’s imposed artificiality and who favor something like a primitivist, back-to-the-land ideology, and ‘technology extremists’ on the other hand, who believe that the creativity of the human species reigns supreme and all problems can be solved by our wits combined with new technologies. The outline of his middle ground is as follows:

1. We live in a wilderness, in which we and our works occupy a tiny space and play a tiny part. We exist under its dispensation and by its tolerance.
2. This wilderness, the universe, is somewhat hospitable to us, but it is also absolutely dangerous to us (it is going to kill us, sooner or later), and we are absolutely dependent upon it.
3. That we depend on what we are endangered by is a problem not solvable by “problem solving.” It does not have what the nature romantic or the technocrat would regard as a solution. We are not going back to the Garden of Eden, nor are we going to manufacture an Industrial Paradise.
4. There does exist a possibility that we can live more or less in harmony with our native wilderness; I am betting my life that such a harmony is possible. But I do not believe that it can be achieved simply or easily or that it can ever be perfect, and I am certain that it can never be made, once and for all, but is the forever unfinished lifework of our species.
5. It is not possible (at least, not for very long) for humans to intend their own good, in the long run, without intending the good of our place – which means, ultimately, the good of the world.
6. To use or not to use nature is not a choice that is available to us; we can live only at the expense of other lives. Our choice has rather to do with how and how much to use. This is not a choice that can be decided satisfactorily in principle or in theory; it is a choice intransigently impractical. That is, it must be worked out in local practice because, by necessity, the practice will vary somewhat from one locality to another. There is, thus, no practical way that we can intend the good of the world; practice can only be local.
7. If there is no escape from the human use of nature, then human good cannot be simply synonymous with natural good.
He acknowledges that we cannot live in the world without changing it to some degree:
We have no way to work at this question, it seems to me, except by perceiving that, in order to have the world, we must share it, both with each other and with other creatures, which is immediately complicated by the further perception that, in order to live in the world, we must use it somewhat at the expense of other creatures. We must acknowledge both the centrality and the limits of our self-interest. One can hardly imagine a tougher situation.
But he also asserts that we cannot take the inevitability of our having an impact on the world to declare a free-for-all, anything-goes attitude towards that impact:
The worst disease of the world now is probably the ideology of technological heroism, according to which more and more people willingly cause large-scale effects that they do not foresee and that they cannot control.