Standard operating procedure for pretty much any science fiction movie involving space travel is the presence of planets around distant stars.
Kirk, Spock, McCoy, and the guy in the red shirt visited a new planet each week. Many were bleak, barren chunks of rock which vaguely resembled the deserts of California. Very few were truly habitable.
In more recent Star Trek series, they have done a better job of depicting planets. Other television series such as Andromeda and Stargate feature a wide variety of planetary types with a range of alien life forms.
Science fiction is rife with the notion that the Universe is filled with planets of every shape and size imaginable. As story ideas go, a new planet is a great way to escape the physics, chemistry, and biology of Earth.
However, despite all of the speculative fiction, it wasn't until 1995 that the first exo-planet was actually discovered. Among scientists and science fiction aficionado this was a long anticipated result - a champagne popping moment.
In the past two decades, a total of 1075 planets in 813 planetary systems including 178 multiple planet systems have been identified. By November of last year, the Kepler mission space telescope had identified a total of 3,568 possible planetary systems in need of confirmation. Even if 20% of these are false positive readings, that is still a lot of planets.
Astronomers now believe that there could be 100 billion planets in our galaxy and that almost every star has at least one planet in orbit.
If this turns out to be true, it certainly changes the calculations used in considering the Drake equation. Most estimates of the number of potentially habitable planets have been on the conservative side of the ledger - maybe 1 in a 100 Sun-like stars.
That number is probably closer to 1 in 5 and may be as high as 40 billion Earth-like planets in the Milky Way. This number begs the question - where is everybody then?
There are theories about that.
Part of the answer may be that while many planets could support life, an equally large number are just too weird for life to every have evolved.
One such planet, designated Kepler 413b, has recently been discovered by the Kepler mission. It wobbles (precesses) widely on its axis in a manner somewhat like the way that a child's top does just before it shuts down.
The planet's tilt can vary by as much as 30 degrees per decade which would lead to rapid and erratic climate behavior. In contrast, Earth's precession is 23.5 degrees over 26,000 years or 0.009 degrees per decade.
In other words, climate change on such a planet would be a daily event rather than occurring over millennial time frames.
Kepler 413b has another layer of weirdness in that it circles a binary star system, consisting of an orange and a red dwarf star, every 66 days. That is days in our time scale because the measurements can't detect the length of a day on Kepler 413b. Still, it would make for a very bizarre year.
On the other hand, one would see the two Sun sunset observed by Luke Skywalker on Tatooine. Astronomers have discovered many such systems so far.
The orbit of Kepler 413b also appears to precess as it is titled 2.5 degrees with respect to the plane of orbit for the binary star system. The planet's wobbly orbit appears to slowly move up and down as observed from Earth.
There would be seasons on Kepler 413b but nothing that would be consistent from year to year or even day to day. How could life evolve in such a system? If it did, it certainly wouldn't be in a form that would be similar to life on Earth.
The Kepler telescope finds planets by measuring the change in light intensity as a planet transits across the face of a star. This requires that the orbit of the planet must lie in a plane that is consistent with the direct line of sight between the Earth and the star. If it is too much outside of this plane, then the planet does not pass between the star and us which means that we can't observe its effects.
In the case of Kepler 413b, it was studied for 1500 days. The first 180 days revealed three transits and provided astronomers with good orbital data. Then it disappeared for 800 days. When it reappeared, 5 more transits were observed in a row.
It was this appearing-disappearing phenomenon that allowed principal investigator Veselin Kostov to be able to predict the structure of the planet's orbit and show that it was wobbling up and down and all over the place.
One thing is for sure, with 100 billion more planets to find and observe, it is likely that there are other planets that are even stranger.
