Astronomers turn their telescopes to the unbounded beauty of the Milky Way, By: Ken Croswell
It's hard to be modest when you live in the Milky Way. Our galaxy is huge. Much larger and more massive than any other galaxy known to astronomers. It spans out across 120,000 light years, and is so big it has dozens of smaller galaxies scurrying about, like the moon orbiting our planet. The heavy elements necessary for life on Earth is forged by the Milky Way's 's abundant stars. When a star explodes in the lesser galaxy these essential elements such as the iron, calcium, and oxygen (all necessary for the different functions in our body) shoots out into space at a million miles per hour and is lost. When a star in the Milky Way explodes, the elements do not disperse but are restrained by the immense gravitational pull of the galaxy. The gravitational pull allows for the elements to form clouds of dust and eventually the new generations of planets and stars. That's what happend 4.6 billion years ago, when the sun and the Earth emerged from a now-vanished nebula.
Have you ever realized that you know your friend's and family's faces better than your own's ? Similarly we know less about the overall appearance of the galaxy we live in than we do about distant galaxies. Nevertheless, scientists have discovered significant phenomenons that inhabit the Milky Way, including the revelations about the huge black hole at its heart.
Every star in the Milky Way revolves around this black hole, named Sagittarius A-star. Earth revolves around the Sun every 365 days. Whereas the Sun completes it's revolution around Sagittarius A-star once every 230 million years. The path of the orbits of the stars reveals that Sagittarius A-star is four million times the mass of the sun! Ever so often it'll swallow up bits of gas or even an entire star. With the immense heat, gravity, and friction present around the hole the remains of the stars is let out as a scream of X-rays. These light up nearby gas clouds, keeping track of the the hole's past feasts. Surprisingly, moving towards the black hole is not the only direction a star can travel. In 2005 astronomers reported an extraordinarily fast-moving star at 200,000 light years from the galactic center. The star, Hydra, was moving at 709 kilometers per second, or 1.6 million miles an hour.
Despite it' violent reputation, areas our the black hole are relatively fertile. Whereas if you traveled many, many light years towards the rim of our galaxy, you'd find it to be a place relatively bleak for prospects of spotting clusters of planets. But these stars, can offer us an insight into the birth of the galaxy itself. Galactic halos inhibit the edge of our galaxy. Dating these stellar halos can lead an astronomer to discover the age of the entire galaxy. In 2005, Anna Frebel began looking for individual stars in the halo. She discovered a supernova, that emitted lots of heavy radio active elements, such as thorium and uranium. Lucky for her, because radioactive elements decay at a steady rate, she could compare it's abundance to the star's today. She estimated that the Milky Way is around 13.2 billion years old, not much younger than the universe it self- which is 13.7 billion years.
Our universe is so big and so old. It provides us with the countless numbers of star make life possible on Earth
The Milky Way is around 13.2 billion years old. The Earth in comparison to the age of the universe is young, only 4.5 billion years old.
Modern human, the Homo Sapiens, are even younger. We were discovered to have originated from Africa only 200,o00 years ago.
We have made it through so many milestones and discovered so many things, it's hard to imagine just how young we are.
In the book "The God of Small Things" that I had read no long ago, a man named Chacko was trying to give his niece and nephew a
sense of historical perspective about the Earth. He told them about the Earth Woman. He made them imagine that the earth- 4.6 billion
years old- was a forty six year old woman.
"It had taken the whole of the Earth Woman's life for the earth to become what it was. For the oceans to part.
For the mountains to rise. The Earth Woman was eleven years old, Chacko said, when the first single-celled organisms appeared.
The first animals, creatures like worms and jellyfish, appeared only when she was forty. She was forty-five- just eight months ago-
when dinosaurs roamed the earth. The whole human civilization as we know it, began only two hours ago in the Earth Woman's life.
The whole of contemporary history, the World Wars, the War of Dreams, the Man on the Moon, science, literature, philosophy, the pursuit
of knowledge- was no more than a blink of the Earth Woman's eye. And we, my dear, everything we are and ever will be-
are just a twinkle in her eye"
