WSU guest opinion: Dwarf galaxies and dark skies
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Adam JohnstonOne of the features of working in a department of physics and astronomy is that I’m always learning new things. A conversation in the hallway and I have a new appreciation for static charge. A question in class makes me reconsider what I know about the chemical change in a kernel of popcorn as it pops. And last week I learned about dwarf spheroidal galaxies.
“Dwarf spheroidals” are one of many concepts and utterances in a physics lecture that could inspire a good band name. (“Coronal mass ejection” sounds especially heavy metal to me; “dipole moment” feels like it could be an adult contemporary headliner at a summer lineup at an outdoor amphitheater.) Galaxies are the islands of our universe that organize stars into massive gravitational metropolises. Typically, these are assemblies of hundreds of billions of stars orbiting as a swirling spiral, the span of which takes even light 100,000 years to cross. Our own galaxy is like this, and it’s from looking out through the plane of this spiral that gives us a “milky way,” that expanse of glowing wisp that can stretch across a dark sky if you’re lucky enough to have such, perhaps in the desert or the mountains. Of those hundred billion stars, we can make out a few thousand with our eyes.
Dwarf spheroidal galaxies are especially enigmatic in that they are so small, perhaps containing as few as a hundred stars. I feel like a hundred is a big collection of most things: people in a room, pennies in a cup, books on a shelf. But in astronomy, this is an astonishingly small amount of anything. When you are cataloging numbers, masses, and distances that need exponents in any unit of measure, countable numbers feel quaint.
In the midst of imagining these quaint spaces, I started to wonder what it would be like to live in such a dwarf galaxy. While it’s unlikely that any self-respecting astrobiologist is looking for life in these lonely assemblies, there being so few places and so little remixing of star remains and new formation of elements in them, I thought it was fun to consider the possibility. What does the sky look like with perhaps only 50 viewable stars at night? What do you imagine the universe is like?
For starters, you’d be hard pressed to use the sky for any kind of navigation. The stars are probably not assembled into recognizable figures. There are no pointer stars of the Big Dipper guiding you to Idaho. And the stories you might pass down from one generation to the next don’t have the anchor or Orion’s Belt or Taurus the Bull. Instead, it’s a few scant dots. The sky is mostly very dark and empty.
And I’d think it would be lonely.
When I look at the night sky, there are lots of connections I make. I’m pleased when I see a favorite assembly of stars, even just the backwards question mark we associate with the constellation Leo. It’s like a comforting terrain and texture to the sky. More than this, I’m connected to a bigger perspective. There’s more than just me, than even just us, here on this lovely yet isolated planet. Imagination and curiosity are sparked from that realization. And so, I’m grateful to be placed on a site from which I can take this all in and wonder.
It’s easy to subvert this, however. Each time we illuminate our sky with our own lighting, porches or street lamps or billboards, we remove some of that dark canvas. Sunshine does this naturally in the day so that we can’t see stars against the blue sky; but we inadvertently do this in our cities and suburbs by choosing to flip a switch. Recently, Weber State added to this as well, lighting a “flaming W” on our hillside. This makes it harder to see the constellation Cassiopeia, a “W” formed by stars circling the northern skies each night.
So here is my humble plea to society: Let’s turn off more lights and expose more night skies. Let’s be a place the residents of those dwarf spheroidal galaxies can’t even dream of, perhaps because they can’t even imagine that such a place as ours could exist. If they do imagine us and our sky, they surely also think we’re wise enough to appreciate all of those stars against a dark, unblemished night.
Adam Johnston is a professor of physics and director of the Center for Science and Mathematics Education at Weber State University, where he helps prepare future teachers and supports educators throughout Utah. This commentary is provided through a partnership with Weber State. The views expressed by the author do not necessarily represent the institutional values or positions of the university.

