Happy Friday, rockstars!
Well, I’ve got my DJ rig packed, and am heading up to Rockville, MD to spin for a school’s Halloween dance. The kids wear costumes, get amped up on sugar, and then we all sing Bohemian Rhapsody. It’s a strange, delightful tradition.
They sure know how to have fun, and their enthusiasm is contagious.
Before I go drop club bangers like The Monster Mash (the persistence of that song boggles me), I’ve got some tracks for YOU! And it’s not Twinkle Twinkle.
The Sky is a Dance Floor
Wednesday evening was delightfully chilly, with a frost due in overnight. Jupiter and Saturn danced in the south, and the Pleiades, the kite-shaped cluster of blue stars, flew up in the eastern sky over the neighbor’s horse barn.
The horse theme continued skywards. “It’s like he’s after the sugar cube” I muttered to myself, trying to remember where to aim the telescope.
Messier 15 is a globular star cluster in the constellation Pegasus, the great horse. Sure enough, the granular appearance of the cluster popped into view as I scanned the sky with the scope, just in front of where the “nose” of the horse would be in the sky.
What It Looks Like
The telescope eyepiece was roughly the size of my eye socket. I looked through it with one eye, and saw a few dozen stars scattered across the view. Of varying brightness, they looked like different sizes. A lovely orange star floated near the cluster.
The cluster itself looked like a round pile of sugar or salt swept into a pile on a black tablecloth. The stars were tightly packed in the middle, and loosened up at the edges of the cluster.
It glimmered with a slightly bluish gray light.
But What About The Track?
Here’s what a globular cluster sounds like. The guys over at System Sounds converted another cluster, NGC 1851, into sound. While not the same as M15, it’s quite similar.
As the radar scans around in this sonification, the radius of the stars is mapped to pitch, so stars farther from the center are higher pitched. The entire image is converted to the sound of a choir, while the orange and red stars are represented by a marimba, and the blue stars are represented by a glockenspiel.
Credit: SYSTEM Sounds (M. Russo, A. Santaguida)
Back to M15
Now let’s talk about the observation of M15 from the backyard.
It’s a collection of over 100,000 stars, and one of the oldest known globular clusters at around 12.5 billion years old.
It’s about 36,000 light years away, meaning the light we’re reading about left this city of suns a thousand years or so before writing was invented.
By cosmic standards, it’s in the next town over. I spotted a galaxy that was 34 million light years away a few minutes later.
What’s with the M15 name? Charles Messier died in 1817, and through his determination to find comets, left backyard astronomers a famous list of cool things to see. He’d find these little smudges in his surveys of the sky, and hope they might be a new comet. After a few nights of watching it, he’d realize it didn’t move, and it was indeed a cluster of stars, nebulae, etc. He finally made a list of “false positives” to avoid when hunting for comets. Today, we relish those same objects as some of the best targets to observe.
This star cluster was the 15th entry on his list: Messier 15, or simply M15.
It’s thought to contain a rare intermediate-mass black hole. Supermassive black holes that lurk at the center of galaxies are a dime a dozen, as are ones that collapse from a single star (stellar mass black hole.) These “medium pizzas” are a rare bird, though.
And nobody can see those!
Special thanks to Christine Malec for her editorial consulting with this new column. She’s worked with NASA on the Chandra and James Webb Space Telescope sonifications, and has been kind enough to nudge me towards writing better alt text.
More Gems from Earth
And finally, we’ve got something that Messier 15 doesn’t have: Beethoven! Let’s wrap up our review of his symphonies, and revel in the gem that’s his eighth. When asked why it wasn’t as popular as his seventh, Beethoven snapped “Because it’s so much better than the seventh.”
Don’t be a square. Dig this, man, and party like it’s 1812.
Zubin Mehta leads the Israel Philharmonic in a rousing performance of Beethoven’s Symphony No. 8 in F major, Opus 93.