From the Mayan calendar and a runaway planet called "Nibiru," from killer asteroids and theories about galactic alignments: The internet is full of talk about the world ending on December 21.

NASA scientists recently addressed some of the most pervasive of these rumors around the dubious date. Take a look:

Mayan calendar

The Mayan calendar began somewhere around 3,114 years before the current era, and is set to end on December 21 or 23 (depending on the translation). NASA scientist Mitzi Adams describes what the Mayans would have done had their civilization lasted and why there is no cause for alarm.

Is an ancient Sumerian planet called "Nibiru" on a collision course with Earth? NASA scientist David Morrison explains how you can dispel this rumor all by yourself.

Galactic alignment

Will the Earth, Sun and center of the Milky Way line up in December? Yes! But as three astronomers explain, it happens every December and is not a sign of doomsday.

Solar apocalypse

Like any other star, the sun will eventually use up its hydrogen core, expand and engulf the Earth. But don't rush out to buy Red Giant insurance for your home by December 21 - you have about 5 BILLION years to prepare. Two NASA scientists explain.

Killer asteroid

There is a real, long-term concern about possible asteroid impacts, and that's why NASA has been scanning the heavens, cataloging them for nearly 20 years. And as two NASA scientists will tell you, not a single object has been found that's on a collision course with Earth.

Polar shift

One internet rumor about the world ending on December 21 is that the Earth will shift on its axis. Astronomer Andrew Fraknoi explains how it's just not possible to change the way our planet rotates in a single day.

More

– The Maya collapsed. Could we?

– Be honest: Apocalypse kinda exciting?