it's so easy to fall for this stuff--just a few weeks ago, there was an email about increased ticket prices and traffic rules which looked totally legit and my boss was printing it and forwarding it to people--but I was able to find out it was a hoax by going to the official government site. But usually, if you check it out, you can tell. A good source for this is Snopes:
http://www.snopes.com/science/mars.asp