Now is definitely not a good time to visit. Sure, there are a lot of places on the planet that are gorgeous this time of year, but generally speaking, even if your plans were malevolent, now would simply not be a good time to invade us.
Well, for starters, governments worldwide are letting their citizens down. Consider the two failed wars the sole superpower on Earth has waged--the American invasions of Iraq and Afghanistan have neither achieved the goals of each invasion nor have they delivered functioning democracies.
Consider the failing global economy--another example of Earth's leaders failing to make the right choices. The very system that exists to support human interaction is crumbling and has been for a decade (or longer) just very slowly--but now is in danger of collapsing. Despite regular citizens understanding how to solve things in the financial arena, their leaders, too addicted to money and power, choose to let things get worse than they need to be even in ways that make them look like fools and hypocrites.
Meanwhile, a global food crisis has been created thanks to abundant food that is priced too high.
Both the US and India have had a hell of a time proving they are competent enough to protect their own citizens as 911 and Katrina has taught Americans, and the recent chain of terrorist attacks in India (including the Mumbai attacks, now in their 3rd day) have taught India (and the rest of the world).
Iceland tear-gassed protesters who were upset about their leaders' lack of responsibility-taking in the collapse of their financial system.
A Belgian leader wants to silence those of us on the Internet who say things he doesn't like--an act that leaders in Iran, Egypt and China have already committed.
Japan, the technological design center of the planet has recently produced a video highlighting how tenuous their grasp on civilization would be if their importation of everything they need were to cease or be disrupted.
Meanwhile, the day after a holiday designed to encourage gluttony, some American citizens have proven they're so interested in being greedy that three are dead in two separate shopping incidents--one in a toy store and another in a big-box retailer.
If that weren't enough for you, Mr. and Mrs. Alien, the strongest military in the world is once again trying to cover up its own mistakes, this time in, what we humans call a "friendly fire" incident. Sadly, this is not the first time this has happened.
Meanwhile, the money behind that military may be drying up--many are beginning to speculate that the US government may be going bankrupt. Obviously, our leaders are panicking about this financial meltdown since there has been almost no fear-mongering in years--sure, there was spying done on American citizens, and talk of an Iran invasion up until six months ago, but when this last financial whammy hit, it was as though those Muslim terrorists were nothing compared to the financial terror those leaders were feeling.
On top of that, there is talk that the very way humans in the first world are functioning and even thinking may be changing on such a fundamental level, it's hard to tell if we're progressing or regressing.
In short, Mr. and Mrs. Alien, our planet is a mess. Infrastructure is screwed, an overwhelming number of our population live in poverty, while those of us who don't are too disorganized to make any difference with any of the problems facing us.
While you may think this disorganization makes us easy targets, let me use an Earth phrase to describe what dealing with us would be like: herding cats.
That's right, an invasion of Earth now would strand you in a quagmire that would take you in upwards of several hundred galactic cycles to extricate from. Even if you had an exit strategy, I'm afraid the chaotic unpredictability of humanity right now would stop you from leaving.
Thanks for your interest in our little planet, but now is not the time. We look forward to our future involvement in your galactic federation, however. We just need to get our space program out of our ass and we'll be right with you guys!
representative of Earth