Celestial News: Peering into infinity
For Steamboat Pilot & Today
STEAMBOAT SPRINGS — In space, there is no up or down, no top or bottom. On Earth, gravity defines our “down” as towards the center of the Earth and our “up” as the direction opposite that, but these have no meaning once you are away from the Earth’s influence.
So, when considering our pancake-shaped Milky Way galaxy, the terms “top” and “bottom” are completely arbitrary. If we choose the “top” of our galaxy to be the side towards which the Earth’s north pole happens to point, then springtime is the time of year when we are able to look right up out of the “top” of our Milky Way galaxy and into the depths of intergalactic space.
Around midnight in mid-April or 10 p.m. in mid-May, the hazy band of the Milky Way temporarily encircles us along the horizon such that, when we lie on our backs and stare straight up, we then are peering out of the top of the Milky Way and into infinity. What’s out there in that deep, dark ocean?
If you could hitch your rocket to a beam of light and travel at light-speed, straight up out of the top of our galaxy, you wouldn’t notice much of a change at all for the first century after leaving Earth, except for the once-brilliant Sun receding into the distance and fading from view. In fact, you wouldn’t notice too much of a change for the first thousand years, as a few nameless stars stream by your window.
After a few millennia, you would leave the starry disk of the Milky Way behind and enter the sparsely populated region of our galaxy called the halo.
As the millennia tick by, you might see an occasional distant globular star cluster sail past, but after 100,000 years of traveling through the halo, there aren’t even any more star clusters to break the darkness.
Looking ahead, you might be able to see dozens of faint fuzzy smudges of light, far in the distance, like so many dandelion floats. These are the galaxies of the Virgo Cluster, so named because, from Earth, we see them glowing behind the stars of our Virgo constellation. Traveling on your beam of light, it still would take you 60 million years to reach the Virgo Cluster. Over 1,300 galaxies of every shape and size would be visible out of your window, including giant elliptical galaxies and majestic spirals like our own Milky Way.
After 10 million years of enjoying your passage through the Virgo Cluster at light-speed, you would spot only an occasional galaxy passing by your window.
About 320 million years after leaving Earth, you would arrive at the Coma Cluster, a rich galaxy cluster containing thousands of individual galaxies. Once you’ve traversed this enormous swarm of galaxies, you would enter uncharted regions of the universe on your way to infinity.
Many of the brightest galaxies of the Virgo and Coma Clusters can be glimpsed with ordinary binoculars or a small telescope this month as you lie on your back and gaze upward out of the top of the Milky Way Galaxy and into infinity.
For information about astronomy-related events in Steamboat Springs, including public star parties at Colorado Mountain College’s Ball Observatory, please contact current physics and astronomy instructor Paul McCudden, at firstname.lastname@example.org or 970-870-4537.
Jimmy Westlake is the former full-time professor of physical sciences at Colorado Mountain College Steamboat Springs and former director of the Rollins Planetarium at Young Harris College in Georgia and the St. Charles Parish Planetarium in Louisiana. His “Celestial News” column appears monthly in the Steamboat Pilot & Today. Visit his website at jwestlake.com.
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