With Warmth the Twinkling Lights
Charles Messier was a comet geek. Perhaps the greatest of the 18th century. From 1760 to 1801, he is credited with discovering, or co-discovering, at least 20 comets. His observatory? The Hôtel de Cluny in downtown Paris, now the Musée national du Moyen Âge.
Today, Messier is best known, not for his comets, but for his catalog of 110 deep sky objects, which are specifically not comets. When one is searching the night sky for comets, it is annoying to spend telescope time on a faint fuzzy thing that might be a comet, maybe. Only to have it turn out, after several nights of observation, that yon fuzzy thing is actually quite stationary in the heavens, and thus not a comet after all. So, as a public service to other astronomers, Messier put these not-a-comet objects on his Do-Not-Call list, where they have been famous ever since. But that’s another story.
Also today, with his telescope set up at the Hôtel de Cluny in downtown Paris, a sad Messier would be unable to see any deep sky objects, at all, let alone a distant comet apparition, being blinded by the light pollution.
The Xuyi Observation Station (XOS) is located on Paoma Mountain, within the Tieshan Temple National Forest, China – a world away from downtown Paris, with somewhat more tolerable light pollution. XOS is a research facility of the Chinese Purple Mountain Observatory, or “Tsuchinshan” in the postal transliteration for “Purple Mountain.” Its primary job is to provide early detection and monitoring of potential incoming enemy fire; that is, alert us to near-earth objects such as asteroids, comets, and artificial space debris, headed our way.
On January 9, 2023, the telescopes at XOS detected a faint asteroidal object in three of their images. Way out there. More than a billion killometers way out there. They reported this observation to the Minor Planet Center (MPC), at the Smithsonian Astrophysical Observatory in Cambridge, MA, which is the official international body charged with managing these discoveries. There, the details of our putative near-earth object was posted to the “Near-Earth Object Confirmation Page” (NEOCP) website. The “Hey there! Anyone else seen this?” website. Nobody had. And by January 30, our lonely object was presumed lost, removed from the NEOCP, and relegated to an entry in MCP’s “isolated tracklet file.”
On the night of February 22, 2023, on the other side of the world in near pristine darkness, an ATLAS telescope hosted at the South African Astronomical Observatory site in Sutherland was doing its routine scan of the southern skies. The Sutherland site had recently joined up with two established telescopes in Hawaii, along with a fourth instrument in Chile, to become the first network capable of scanning the entire dark sky every 24 hours.
ATLAS is the acronym for “Asteroid Terrestrial-impact Last Alert System,” one of an ongoing set of earth defense projects administered by NASA. ATLAS is, in fact, looking for the same near-earth objects as Purple Mountain Observatory. It just has a snazzier acronym for a less poetic calling card. But make no mistake, being bombarded by celestial asteroids is a real thing. And I assert it is, in fact, comforting that there is international redundancy in these early warning systems. Just imagine if SpaceX had a monopoly on preventing a rapid unscheduled planetary disassembly.
And so, deep in the Southern Hemisphere – roughly three weeks after the Purple Mountain Observatory object was presumed lost -- the ATLAS-Sutherland data bots set off the alarms after detecting four observations of a new potential comet, way out there. ATLAS referred the data to the MPC, which posted the object to its “Possible Comet Confirmation Page” (PCCP) website. This time other sites were able to confirm the comet, and this added enough new data that MPC could calculate its orbit. At that point, the staff at MPC recognized that the ATLAS comet of Feb 22, and the Purple Mountain Observatory near-earth object of Jan 9, were one and the same.
And thus was born, by Electronic Telegram No. 5228 on February 28, 2023, comet C/2023 A3, named “Tsuchinshan-ATLAS”, in honor of the two observatories key to its discovery. Tsuchinshan-ATLAS was projected to become the brightest comet in 27 years, and by September gorgeous photographs of the comet were appearing seemingly everywhere. This I had to see.
Before I could see the comet, however, I needed a place from which to look. Unfortunately, the Hôtel de Cluny is no longer in the running. A pity that. By early October, Tsuchinshan-ATLAS had finished its parabolic swing around the sun and was now racing rapidly away, from the comet’s point of view, back to its home origins in the Oort Cloud. From our point of view, it was now trailing behind the sun, a bit further each night, chasing it down below the western horizon. It’s all relative. As a result, the comet was set to appear low in the western sky for a short time after dark.
On the evening of October 18, a little before sunset, we pulled into Calf Mountain Overview, on the Skyline Drive. I confess to having cursed Skyline Drive in the past, while hiking trails in Shenandoah National Park. It seemed a sacrilege to run a two-lane strip of asphalt down the spine of a national treasure, splitting in half the fragile woods and mountains that were already too geographically narrow. But they got the name right. Skyline. And I was grateful for the access on this night.
Calf Mountain Overview is a scenic pull-off, at 2,500 feet elevation up the mountain, affording wide views westward over the Shenandoah Valley. Perfect for viewing Tsuchinshan-ATLAS. We weren’t alone. A number of other cars dotted the parking area, and folks with cameras were already out ready to play Messier. Several tripods stitched the grass to the ground. I set up my tripod and camera and waved a magic incantation with my compass. We waited for the dark. And the comet.
“There it is!”
“Where? I can’t see it!”
“Right about there.”
Separate sets of fingers pointed simultaneously to the four corners of the earth.
“Here. It’s on my cell phone camera!”
“Let me see.”
“I don’t see it!”
For all its virtues, Calf Mountain Overview has one major shortcoming as a comet observatory: it sits directly above the city of Waynesboro. No disrespect to Waynesboro, and its 23,500 people, but boy, can they light it up. And the Waynesboro light pollution couldn’t care less about the view of a once in the past 27 years comet, even at 2,500 feet elevation.
The official Shenandoah National Park website puts it this way:
Yet here at Shenandoah it’s also important to note that some of what would otherwise be regarded as light pollution is beautiful to people. Many park visitors stand at overlooks along Skyline Drive at night and view with warmth the twinkling lights of the small towns and communities in the Shenandoah Valley or the Virginia Piedmont.
It was cold standing at Calf Mountain Overview. Most of the assembled Messiers gave up without ever seeing the comet, and they left. I eventually found a smudge of Tsuchinshan-ATLAS in some wide field shots using a 20 sec exposure, but no amount of image processing hocus-pocus would be enough to save those comet photons forever lost in the Waynesboro glare.
What would Messier do? What would he do on June 5, 1764, when his latest potential comet turns out to be just an ordinary, static, ain’t movin’, globular star cluster? What would he do after he assigns this star cluster the number 19 and sticks it on his Do-Not-Call list? On June 6, 1764, Messier would go back to the telescope. At least, I think he would. After all, in a lifetime of searching the sky, he discovered 110 not-the-comet objects and only 20 actual comets. That takes some dogged dedication.
So two days later, still blessed with the promise of clear skies, I went back to the telescope and moved deeper into the Park.
Big Meadows is just that: a big expanse of wild grassland located along Skyline Drive around mile marker 50, at Blackrock Mountain, elevation 3,668 feet. An old legacy crab apple tree in the middle of the meadow hints at a history of farm pasture and orchard, back before the displacements in the 1930s. Now Big Meadows is a recreational development facility sporting a gift shop, visitor center, campground, picnic area, lodge, taproom, and restaurant. On this evening, at the peak of fall colors, the place was packed to capacity with leaf peepers traveling the Drive for the views. Traffic was hectic and things didn’t look all that promising.
Big Meadows’ namesake field is a star gazer’s delight, providing wide, unobstructed 360 degree views of the sky, and wide open space in which to spread out. Towards dusk, I set up a tripod, camera, and camp chair, all pointed in the general direction of a patch of darkening sky in which I hoped Tsuchinshan-ATLAS would appear in good time. As the stars became visible, first Vega, Arcturus, Altair, then planet Venus low in the Southwest, the sky at Big Meadows did not disappoint. Not the inky darkness of ATLAS-Sutherland, not even the dark of the North Maine Woods, but plenty dark enough to invoke that sense of awe that comes from looking deep into the Universe from a meadow on our tiny speck of Earth.
“Are you part of the star gazing program?”
I’m sorry?
The meadow had been peaceful and quiet all twilight. Despite the horde of guests at Big Meadows, when darkness fell they were all apparently absorbed into the restaurant, and the taproom, and their tents and campers, all a distant mile up the service road from the meadow. So it was a surprise to be approached in the dark by someone looking for a star gazing program.
Sorry, I’m new here. Is this the Hôtel de Cluny?
Sure enough, very shortly my tripod and camp chair were in the middle of a scrum in the middle of the meadow. Chatter was everywhere and headlamps flashed in all directions like faux lightsabers. Over at a big reflector telescope, Ranger Noah was set to entertain and educate a big group of camp visitors, expertly capturing them with the science and lore of the night sky. Greek mythology mixed with NASA deep probe discoveries. I wondered if Messier ever got to enjoy an astronomy lesson while simultaneously searching the sky for a comet.
I found Tsuchinshan-ATLAS right where the MPC ephemeris said it would be. It was still not visible to my unaided eyes, but it was far easier to find in some test exposures than it was when last I peered through the Waynesboro radiation. The comet framed itself to rule over a hillside extinction, decorated with the silhouettes of scattered trees. An unknown fellow Messier disciple photobombed my layout by planting his tripod right in the way, far downfield. But I ended up liking the pseudo self-reference so much that I shot a bunch of frames anyway.
It is sad that Charles Messier’s observatory in the Hôtel de Cluny has been displaced by the urban blaze of Paris. That so much of the world has been blinded by the light we think we need, or don’t even think about at all. But hope. There are still dark skies in the land of humans. There are still locations where we may be haunted by the majesty of celestial visions. Let’s preserve them.
This one’s for you, Charlie.