How old is the Earth: Cool Analogies Included

          To start this off, there is no way to tell exactly how old the Earth is because it is SO OLD. We can get close and the closest we got was 4.5 billion years old give or take 70 million years. So if that is all you wanted to know, stop reading. But there are more facts ahead. I will be going over how we have determined the Earth's age and analogies to help you grasp how old the Earth is. So for those of you who stuck around, let's get right in to it.
          Scientists have determined the age of the Earth by observing Lead levels in Zircon. Zircon is similar to Quartz and both are extremely resilient, so they can last a long time. The fact that Zircon can last so long is one of the reasons why this method is used. You may be wondering why Lead is in Zircon, so let me explain. Zircon has small traces of radioactive Uranium in it and this Uranium is similar enough to Zirconium, where Zircon gets its name, that it can take Zirconium's place when the mineral is forming. This Uranium then radioactively decays into Lead, which means the more Lead in a certain piece of Zircon, the older that Zircon is. This makes sense because the older the Zircon is the more time it has to produce lead. The age is then determined by using the half life of radioactive Uranium and comparing it to the ratio of Lead to Uranium. If the ratio is in Lead's favor, then it is older than a ratio in Uranium's favor because it hasn't decayed yet. This can get complicated due to the fact that there are 2 kinds of decay, 235U to 207Pb which has a half-life of 701 million years, and 238U to 206Pb which has a half life of 4.47 billion years old.
         Now for the fun part, the analogies. First off, if we had one piece of paper for each year that the Earth has existed and put them in a single stack, that stack would be 50.86 times taller than Mount Everest. The oldest person that ever lived, Jeanne Calment, lived for 3861561600 seconds when rounded to the nearest day. It would have taken her 20.24 more years for the number of seconds she lived to equal the number of years the Earth has existed. Usain Bolt can run at a speed of almost 45 km/h, if he were to run 4.5 billion milometers, it would still take him 100 hours.  Mind still not blown? Well here is one last comparison.  If we had a single grain of sand for each year the Earth has existed, then it would way 2700 kilograms, or as much as 2 hippopotamuses. Mind still not blown? Well here is one last comparison.
         If you are interested in the math of the Uranium-Lead dating method or you want to know possible problems when it comes to dating the Earth, read my next post.  Follow on twitter at Planet Earth and visit the Facebook page at Let's Give The World A Chance. Don't forget to like, rate, and subscribe, oh wait, this isn't YouTube. Anyway, stay green Earth, see you all next post.