Introduction to Astronomy & Astrophysics
I’ve included a section on astronomy and astrophysics on this site because I’ve loved astronomy and space exploration since I was a ten year old checking out a pile of high school level books on stars and planets. Before I put myself under the nearly perpetual cloud cover of Juneau, Alaska, I was an active amateur astronomer. Observing shadow transits on Jupiter was my idea of a good time. I still monitor a lot of astronomy and space exploration efforts over the Internet. One of my web browsers has NASA set as its home page.
I tell you this because this love and enthusiasm for astronomy has led me to many jarring moments in books, TV and movies where the total disregard for astronomical reality jarred me out of the story.
Some of these moments came as a result of not understanding astronomical distances, usually involving small thinking.
Some examples of small thinking: In the Twilight Zone episode Elegy, an astronaut marveled that they had traveled 665,000,000 miles and were amazed that they found such an Earth like environment so far away. I’m amazed also, but for different reasons. The Earth is about 93,000,000 miles away from the Sun. The only available objects, depending on their orbits, within a 665,000,000 miles of Earth are the Sun, Venus, Mars, a set of airless asteroids and Jupiter and its satellites. None of them are remotely habitable by human beings without serious protection. If there is another world that where humans can walk unprotected from the elements, it will be in another solar system. The nearest one is four and a half light years away. For comparison, 665,000,000 miles is roughly one light hour.
Another example of a writer not comprehending the vastness of space can be found in the Star Trek The Original Series (TOS) episode Arena. At the end of that episode, Mr. Sulu remarks “Captain, it’s impossible but… there’s Sirius over there when it should be over there! And Canopus, and Arcanus. We’re… all of a sudden we’re clear across the galaxy. Five hundred parsecs from where we are. I mean where. I mean-”. Mr. Spock checks the readings and agrees with Sulu with words like “Agreed. We have been thrown clear across the galaxy, about 500 parsecs (1625 light years).” Don’t get me wrong. Instantaneous transport of a starship large enough to hold 500 people is a massive feat. But the Milky Way galaxy is about 100,000 light years across, according to NASA’s Imagine the Universe site, annotated elsewhere. Being thrown 1,650 light years is just barely 1% of the galaxy’s diameter.
Another pet peeve of mine is the habitable asteroid. Going back to the Twilight Zone, there are a number of episodes that take place on asteroids. There is also the Star Trek: TOS episode Metamorphosis that takes place on a “small asteroid.” These places appear to have Earth levels of atmosphere and gravity. <Resisting urge to jump up and down screaming NO, NO, NO!>. In all such cases the habitability problem is a matter of mass. The amount of mass a body has determines its gravity. A body’s gravity, and to a lesser extent, its distance to its primary star determine how much of an atmosphere that body has. There are about a half million known asteroids in our solar system. If you could somehow combine them into one body, the resulting mass would still be less than that of Earth’s Moon, according to NASA’s Exploration Asteroid page. The Moon has 1/6 earth gravity and no significant atmosphere. An unprotected human on the Moon would boil in his own fluids from lack of air pressure. The individual asteroids, even the largest ones, are much, much less the mass of the Moon. From most of them a space suited individual could launch themselves into orbit or even escape the asteroid entirely.
Habitats WITHIN asteroids (like Star Trek: TOS – The World is Hollow and I have Touched the Sky) are more plausible but still can’t overcome the issue of gravity without consciously invoking an artificial gravity generator. These don’t exist, but at least you are addressing the issue.
One final issue isn’t so much a pet peeve as a caution against a favorite plot device in a number of TV shows and movies such as Star Trek: TNG – The Inner Light where people work against time before a habitable planet’s sun goes supernova. When you review the stellar evolution and astrobiology resources below, you’ll notice that stars large enough to go supernova only last for a few tens of millions of years and that evolution as we understand it takes billions of years to evolve sentient life. Supernova stars blow themselves and their associated systems to bits long before life could crawl out of the oceans of a planet orbiting a large star. There are plenty of other ways to wreak havoc on worlds including super solar flares and sending a sun-like star into a red giant stage. Or you could invoke a “stellar manipulator” that allows you to avoid the usual rules. But at least nod to the rules of stellar evolution. Hard science fiction fans will thank you.
And now, some resources to help you avoid these traps and others.
Sources for intro:
Baby Planet – TV Tropes – http://tvtropes.org/pmwiki/pmwiki.php/Main/BabyPlanet
The Inner Light – Star Trek TNG – http://en.wikipedia.org/wiki/The_Inner_Light_(TNG_episode)