Yeah, but what I'm wondering, is the 15x the value after the distance is considered? Because it can be 15x brighter, but 15x farther too, making it dimmer. Then if it's smaller like Svenno is saying, it makes it even less visible.

The article says it will be clearly visible during the day, so it must be pretty bright. The moon is just barely visible during the (sunny) day.

Makes sense.

Really?

Well, both civilizations had very good astronomers so maybe the 2012 thing is some kind of astronomical event that could be important for their believings but that it is only a curiosity for us.

But even then it's a curious coincidence.

The moon is very visible during the day, especially in November.
Anyways what do they mean with 15x brighter. I don't think it will be total light received on earth compared to the moon. Brightness at the center probably, and since it will be tiny compared to the huge disc of the moon I doubt it will do much for illuminating the night.
Both are visible by reflected sunlight, although the ice from comets is a lot more reflective it can't compete with the area surface of the moon.
It should be a cool sight anyway, I wonder how long the tail will be seen from earth.

Actually I'm wrong about the size comparison, comet's tails can easily be wider then the earth's diameter and extend for the distance between the earth and the sun, yet it's all about density in the end. What part of the tail is dense enough to be visible.
And even an earth sized reflector at that distance is still tiny, see venus transit. (Venus being the size of the earth and only a pin prick, while the moon covers the whole sun)

"The 2012 phenomenon comprises a range of eschatological beliefs according to which cataclysmic or transformative events will occur on 21 December 2012.[1][2][3][4][5] This date is regarded as the end-date of a 5,125-year-long cycle in the Mesoamerican Long Count calendar. Various astronomical alignments and numerological formulae have been proposed as pertaining to this date, though none have been accepted by mainstream scholarship.

Similarly, the Sun's December solstice position (in the northern hemisphere, the lowest point on its annual path; in the southern hemisphere, the highest) is currently in the constellation of Sagittarius, one of two constellations in which the zodiac intersects with the Milky Way.[64] Every year, on the December solstice, the Sun and the Milky Way, from the surface of the Earth, appear to come into alignment, and every year, precession causes a slight shift in the Sun's position in the Milky Way. Given that the Milky Way is between 10° and 20° wide, it takes between 700 and 1400 years for the Sun's December solstice position to precess through it.[65] It is currently about halfway through the Milky Way, crossing the galactic equator.[66] In 2012, the Sun's December solstice will fall on 21 December."

http://en.wikipedia.org/wiki/2012_phenomenon#Galactic_alignment

1-Eschatological beliefs?

2-Solstice always falls between the 20th and 21th. Al 4 of them. It's somthing even the ones who build Stonehedge knew.

3-The Sun and Earth aligment mean nothing for the Milky way. Our mass is insignificant. Not too many years ago all the planets in our solar system aligned iwht the Sun. Some even though that it would cause a gravity influx that would cause a giant Solar Flare that would vanish all the planets. We're still here.

4-Am I reading that right? Is the one who wrote that saying that either we (Earth), the Sun or the Milky way will crash with Sagitarius? lol

Not sure about all that text.  I just remembered something about galactic alignment and tried to deduce something from wiki.  I don't believe in anything except maybe it will be a new period of awakening (such as we realize that we are fucking the planet up).  I thought we were supposed to align with the Milky Way or something.  My astronomy knowledge is quite lacking.