For those who are interested, here is some background on the planets.
There is a binary pair of habitable planets, which are both inhabited by sentient creatures. One is inhabited by reptilians, and the other by amphibious humanoids. Both planets orbit a yellow sun, and are closer to the Sun than Earth, making them a little hotter. These planets are also earth sized.
These creatures' scientists and astrologists recently discovered that soon a moon sized object will pass by, disrupting their gravity enough for the planets to collide. (Gasp!) However, the CEO of the company Spaceships R Us, Mr. Benevolence, owns two large colonies on another planet in the solar system. He is gathering samples of all life in the planets, and is shipping them to these colonies. His company is having a competition to decide who will get to survive, and everyone has the option to enter.
The moon sized object will do its work in 1-5 years.
Out of the 8 billion people on these two planets, eighty million will be chosen to journey to these colonies. The factors are people's physical health, age, gender, religion, race, species, marital status, and intelligence in different fields, as well as a random selection of ordinary people (maybe 25% of the people going). So pretty much everything is a factor. And guess what? All major religious leaders, such as the alien pope get to come!
Note - The idea behind this is to preserve as much about society and the plants as possible before they are destroyed. Then, once the planet becomes stable again, to help repopulate it.
How would people react to this? It would be a tight kept secret on the dates these events occur, such as when the ships leave, and when the cataclysm occurs. There would also likely be many ships taking off, each with hundreds of thousands of people. The punishment for stowing away (which is not widely known) is ejection via airlock. Would the populace begin rioting and chaos, or would the hope of being chosen be able to assuage their fears?
Note - Results are given only to individuals chosen, and only those chosen receive the time frames and locations for their personal departures. Breaking up family units, such as choosing someone but not their wife, is rare. Same with families that have children under adult age.
Edit - Their society is almost exactly like an advanced North America (Because North America is more descriptive than Earth), but the reptilians are a little more aggressive, and the others a little more passive. But the difference is very slim, and not enough to differ too much as compared to humans