HUMANS have always been captivated by the Milky Way. To the ancient Greeks, it was a squirt of breast milk, while the Mayan farmers of Mesoamerica saw it as a growing maize stalk. Today, astronomers understand that what we see when we gaze up at the hazy streak of light stretching across the night sky is actually just one part of our host galaxy – one of four spiral arms emanating from an enormous disc of dust and gas that together contain at least 100 billion stars.
But even as we have traced our cosmic origins on the grandest scales, from the big bang to the growth of trillions of other galaxies entangled in vast webs, the history of our galactic backyard has remained opaque. It isn’t for want of trying. The problem is that when you are inside something, it can be hard to see what is really going on.
Now, a clearer picture of how our galaxy, the Milky Way, came to look the way it does is beginning to emerge thanks to data gathered by the European Space Agency’s Gaia satellite. Hidden patterns in the movements of stars have taken astronomers by surprise, unveiling in rich detail a turbulent history of cataclysmic collisions and aftershocks.
Some say that soon we will even be able to pinpoint the specific events that led to the formation of our sun – the reason we are here to ponder such things. “It’s our heritage, a way of knowing.
Every star that you see in the sky is part of the same enormous galaxy. Our solar system resides in a galaxy called the stuffed with between 100 billion and 400 billion other stars, many of them with planets of their own like a streak of milk across the sky. That hazy white band is made up of stars, dust and gas. It looks like a flat stripe because we are viewing it from within its disk; if we were able to get above the Milky Way, it would look like an enormous spiral about 100,000 light years.The arm that’s home to Earth is a smaller one called where our solar system resides about 26,000 light years from. The galaxy is rotating, and it takes us about 240 million years to complete one circle around its middle.
The centre of the galaxy is a dense and chaotic place, with stars and gas hurtling around the Milky Way’s supermassive black hole, It has a mass more than 4 million times the mass of the crammed into a diameter just about 30 times the sun’s width.
The Way is just one of more than 100 billion galaxies in the universe – but it’s the one that we call home.
One of our neighbouring galaxies is dying, and it is the Milky Way’s fault. Our galaxy is nearly done ripping the Sagittarius dwarf galaxy to shreds, according to a series of simulations of the pair’s epic dance.
The is one of the Milky Way’s satellites, and its orbit around the Milky Way has been slowly closing in over billions of years. Eugene Vasiliev and Vasily Belokurov at the University of Cambridge used data from the Gaia satellite to.
You must be logged in to post a comment.