December 21, 2012: Are we all going to die?Section: ____________ Written by: Jeremy Jones

Over the past few years, websites, books, and even a bigblockbuster movie have popped up concerning the ancient Mayan\"prediction\" that the world will end on December 21, 2012. It istrue that the 13th bak'tun of the Mayan calendar will end onDecember 21, 2012. So what?, the 12th month of the modern calendarends on December 31 every year. However, the end of the 13thbak'tun is supposed to be a special occasion (similar to the year2000 was for us, or the last year of a decade).

If that was the end of the claims proposed by these websites,books, and movies, then we could just leave it up to thehistorians, anthropologists and archaeologists to deal with themyths. Unfortunately, the 2012ers (all conspiracy theorists need an\"ers\" behind their collective name) decided they'd make a fewclaims pertaining to how the world is going to end. Theseclaims delve heavily in the pseudo-science astrology (the study ofhow the stars and planets affect our daily life). We will take alook at a couple of these claims, namely the claim that a planetaryalignment will destroy the Earth and the claim that a previouslyunseen planet will destroy the Earth.

Forces of Planetary Alignment

For centuries, astrologers have \"known\" that planetaryalignments are times of great stress and disaster, so it's nosurprise that it's put forward by 2012ers as one of the ways theworld will end. However, no astrologer has ever come up with ascientific theory or any evidence concerning why planetaryalignments are such an issue, but let's take a look at it anyway.There are four different ways that matter can interact:gravitationally, electromagnetically, and through the weak andstrong nuclear forces. The two nuclear forces only work for nucleardistances, so we can drop those from consideration. The planetshave no net electric charge, but some of them (including Earth)have magnetic fields. Could they be interacting? Well, no. Themagnetic fields of the planets are incredibly weak, and thedistances between the planets so large that they have no effect.The Sun's magnetic field interacts with the Earth's, but that won'tchange if you have planetary alignment.

This leaves one force to analyze, gravity. Keep this question inmind as you do this part of the lab exercise: can the gravitydistribution in a planetary alignment change the Earth's orbit?

Given in the table below is the mass of 8 bodies in the solarsystem (the Sun and the planets that aren't Earth). Also given isthe distance from Earth to these different bodies when the planetsare all aligned.

Body	Mass (g)	Distance (cm)	Distance2 (cm2)	Force (dynes)
Sun	1.99x1033	1.50x1013
Mercury	3.30x1026	9.12x1012
Venus	4.87x1027	4.14x1012
Mars	6.40x1026	7.84x1012
Jupiter	1.90x1030	6.29x1013
Saturn	5.69x1029	1.28x1014
Uranus	8.70x1028	2.72x1014
Neptune	1.03x1029	4.35x1014

In the table above, calculate R2 and F for each body. The forceof gravity between a body of mass M and the

Earth is Fgrav=(3.98x10^20) (M/R^2)(R is the distance from the Earth to that body when the planets arealigned) R2