Some 5 billion years ago, a swirling light-year-sized pocket of gas and dust collapsed into a disk to form our solar system. This flat disk continues to swirl as planets and asteroids experience their perpetual Newtonian fall around the Sun. The flat disk of the solar system has a practical implication for stargazers: it means most solar system objects are confined to a narrow band of the sky as seen from Earth. The imaginary line through this band is called the ecliptic, and the group of constellations that fall along the ecliptic is called the zodiac.
Why the 2012 Mayan Doomsday is Nonsense
According to hundreds of internet sites and thousands of misinformed citizens, the world will come to and end next week. That’s because, as the story goes, the Mayan calendar predicts an alignment of the earth, the planets of our solar system, and the center of the Milky Way. This alignment will cause all sorts of catastrophe, from a sudden change in the direction of the Earth’s rotation to the collision and destruction of our world by a rogue planet called Nibiru. And it’s all supposed to happen next Friday, December 21, 2012. Presumably on Mayan standard time.
It is all hokum. Here’s why.
The Last Stars
With the simplest telescope, nearly anyone can see the birthplace of new stars in glowing blisters like the Orion Nebula or the Swan Nebula. So you might think star formation is commonplace in the Milky Way. But it’s not… astronomers estimate just four new stars are born each year in our galaxy. What’s more surprising, the rate of star formation is declining as primordial gas in the early universe is consumed by new stars. Which means in the distant future the bright blue-white stars that light our night sky will become far harder to find…
Where is the Center of the Universe?
In the 1920’s, Edwin Hubble found that galaxies appear to fly away from us in all directions. The farther a galaxy, on average, the faster it recedes: this is Hubble’s Law. We now know that receding galaxies are caused by an expanding universe, a universe which began in a Big Bang 13.7 billion years ago and has been expanding ever since. But it seems odd, does it not, that galaxies recede in all directions from our point of view? Does this mean we’re at the center of the universe? And if we’re not, then where is the center of the universe, the place where the Big Bang happened?
How Big is the Universe?
How big is the observable universe? It seems a reasonable question to ask. But the answer is not so simple. Let’s have a go at this question anyway because, well, as intelligent beings who live in the universe, it is something we should know. And arriving at the size of the universe is more interesting than the answer itself…
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