Enigmatic Universe

September 7, 2010

If its nighttime where you’re reading this, and if you’re blessed to live in an area that isn’t swamped by light pollution, you might be able to see the stars in our night sky. Just west of Taurus and just east of Pisces is the constellation Aries. Hiding between those stars is the galaxy dubbed NGC 772, an unbarred spiral galaxy 130 million light years away. Because it’s 130 million light years away, we can only get a picture of what this galaxy looked like 130 million years ago. What if with an especially-powerful telescope we saw a planet forming in some star in this galaxy? By the time that light got into our telescopes, that solar system today would be remarkably different from the image we see. Our view of these deep space objects are so out-of-date that we have virtually no way of knowing what is going on in these places in real-time.

So what if we had a telescope powerful enough to detect a certain dim star in that galaxy? Assuming that the star we were looking at was lined up in just the right way, we might be able to detect a planet orbiting in that system. And we point our telescope at this star and we find that periodically, that star gets even dimmer at a regular interval. We conclude that this dimming is caused by a planet that makes a transit between our telescope and that star, blocking some of our light and it passes in front. Astronomers call this the transit method of detection, and with this method, planet hunters have found hundreds of planets, some of them are even rocky like our planet Earth. For years, we check the regular dimming of this star and we take note of where and when the planet passes in front of its star. This occurs on regular intervals and we use it to determine the volume of the planet based on how much light is being blocked. This method called transit photometry; our current technology only allows us to find planets within a certain distance of the star it orbits, though, but it’s effective at seeking out smaller-mass planets like the rocky terrestrial worlds in our own inner solar system.

From there, we could figure out the planet’s mass based on its gravitational pull and radial velocity measurements to quickly we deduce from all of this data that our planet is made of rock, slightly more massive than earth, and orbiting close to its star. Because we have a powerful instrument that could detect the composition of this planet’s atmosphere, we learn to our surprise that this planet’s atmosphere is nitrogen-based with carbon dioxide, water vapor and other gases. Imagine our surprise when we discover this planet is similar to Earth in so many ways that it could be habitable to life as we know it.

Planet habitability is the measure of a planet’s potential to sustain life, which is determined by a wide range of factors. For instance, where a star is located in the galaxy can determine how likely it is life will arise on a planet orbiting that star. Stars located closer to the galactic center are more likely to be irradiated by the cosmic rays emitted by galaxy’s massive core. Also, stars form much denser clusters in the center of our galaxy, so it would be likely that these planets would get caught in the supernova explosions by their neighboring stars. This would mean that planets would get doused with high-energy radiation that would rip apart organic molecules and make it difficult for life to form. The Earth is located on the outer edge of the Milky Way galaxy, so we’re in less danger of this radiation bombardment. However, as we look at farther from the center of the galaxy, elements heavier than hydrogen and helium get rarer because a lower density of stars mean supernovas happen more infrequently and fewer metals get formed by nucleosynthesis, so building a planet made out of anything other than hydrogen gas is harder at the edge of our galaxy. Assuming a star is located in the area in between either extreme, it could be host to a habitable planet, one that is not only conducive to life as we know, but one that stays habitable long enough to spawn life.

Check out our next post when we take a closer look at a Solar system in the Arietis galactic habitable zone, home to a planet that will serve as the subject of our upcoming thought experiment.


Explanatory Universe

September 2, 2010

This blog is a creative writing assignment and an example of “hard science fiction”, science fiction based heavily in technical details and strives to be accurate scientifically, based on the current astrobiological paradigms. I chose to make this blog a project in hard science fiction because years earlier, I started a thought experiment in my spare time aimed at figuring out what a human explorer would experience on another habitable planet. What color would the sky be, and how would the human cope with that planet’s gravity, atmosphere, and local life forms? From there, the thought experiment evolved into a new idea: how would the indigenous life forms adapt to their environment?

I kept coming back to this idea for years, slowly building a sentient alien life form with consciousness, and working backwards to figure out what kind of environment could have spawned this creature. As I poured more and more time into this thought experiment, I began to build an animal phylogeny, and I developed a greater understanding of how climates on Earth change. For the entire time, I went without giving this planet or its inhabitants a name, referring it only as “the planet” or “the creatures”. I realized for this assignment, it might be of my benefit to give my planet and the beings on it some kind of name.

When I discuss the timeline of events leading up to the creation of sentient life on Areios, I should mention that I have decided to put all of this deep into the future, at a time long after our Sun becomes a red giant. When I discuss the origins of this solar system, I refer to the dates as relative to the point of oogenesis; the time in history where the first sentient beings were spawned on Areios. While I express this as a single well-defined event, the path to sentience is actually a convoluted path that involves a not-so-clear distinction of what’s sentient and what’s not. We’ll discuss this much later, but it should be noted that the more scientists study the nature of intelligence, the more we realize that formerly human-solely traits are actually shared by other animals, like culture, language, and emotion. But for the sake of this blog we don’t need to be that specific, so we’re going to say that Hemera and this solar system spawned 14 billion years before the advent of our sentient life-form, the Areia.

I decided to give them a name evocative of Ares, the god of war, based off my earliest model, a picture I drew as an assignment in middle school art class with a gnarly-looking alien conqueror. I named the planet Areios, in Greek it is the masculine adjective form of the word Ares. The creatures that would inhabit the planet, from the earliest microbe to the most complex multicellular creature, would be referred to as the Areia, the feminine adjective form of the word Aries. The star that these planets orbit around will be named Hemera, named after the Greek personification of day.

The three moons that would orbit this planet Areios would be named after a myth in the Illiad; two giants named Otus and Ephialtes chained Ares and put him in a bronze urn, where he remained for a lunar year. The legend continues that the giants’ stepmothers Eriboea eventually learned what happened and sent Hermes to free the God of War. The three moons of Areios are named Otus, Ephialthes, and Eriboea, with the second moon Eriboea formed by the impact theory and the first and third moon by the capture theory.

The only other planet in the Solar System is a gas giant more massive than the planet Jupiter. I named this Jovian planet Alkyoneus. Alkyoneus was the eldest of the Thracian Giants of Greek mythology. The Alkyonides were, in Greek mythology, the seven daughters of Alkyoneus; they will provide the names of the seven largest moons of the Jovian giant. These moons will be mentioned again in the final assignment of the semester, when we explore the Areia as a spacefaring civilization. In the future, the Alkyonides will serve as major space colonies for the first sentient Areia as their civilization moves beyond their homeworld.

This blog will start with a discussion of the galaxy the Hemera star system orbits around, describing how certain zones within a galaxy are thought to be more conducive to life than other. Next, I’ll move on to a discussion of the Hemera solar system, describing the mass, composition, orbit and formation of Hemera and the objects that orbit around it before delving into the characteristics of Areios than make it habitable, including the interaction of Areios with its three moons.