THE WANDERING ASTRONOMER
Tuesday, September 5, 2023
Galactic Tick Day
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Celebrate Galactic Tick Day at the Southworth Planetarium!
Saturday, September 9, 2023 11:00 a.m. - 2:00 p.m.
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Do you feel that?
Concentrate and try again.
Do you feel it now?
Motion.
Not lethargic motion like the gradual slip of a tectonic plate, but rapid motion, akin to that of an ICBM fired in furious anger, only more than thirty times faster. How fast is that speed, one might wonder? 143 miles per second, which equates to 514,000 per hour or 12.3 million miles each day!
Not lethargic motion like the gradual slip of a tectonic plate, but rapid motion, akin to that of an ICBM fired in furious anger, only more than thirty times faster. How fast is that speed, one might wonder? 143 miles per second, which equates to 514,000 per hour or 12.3 million miles each day!
What could possibly be moving so swiftly?
You are. Or, more precisely, the solar system you inhabit is traveling at that unimpeded, devil-may-care velocity through the churning spiral arms of our Milky Way Galaxy. Refer to the graphic below to see our approximate position within our home galaxy. (Note: Naturally, we are unable to photograph the Milky Way from an external standpoint. Instead, some clever soul snapped a photo of a galaxy which closely resembles our own and pinpointed our location in it relative to the nucleus.*)
Every one of the nearly 400 billion stars residing within the Milky Way moves at breakneck speeds relative to the nucleus as the spiral arms turn pin-wheel like around it. Our Sun and its retinue of attendant worlds have been moving with this stellar throng since its formation nearly five billion years ago. It completes an orbit around the nucleus approximately once every 225 million years, a time period known as a galactic year.
Every 633.7 days, or 1.7 361 years, the solar system moves one centi-arcsecond along this orbit. One one hundredth of an arc-second is an unfathomably miniscule angle. To lend you an idea of this measure, take out a dime. (If you're employed by the University of Maine system, take out a penny and pretend it's a dime.**) An arc-second is the angular distance that dime would subtend if it were 2.5 miles away from you.
Galactic Tick Day celebrates the passage of each tick, or each centi-arc second. Don't feel ashamed if you've never heard of this holiday. It is of quite recent vintage. San Francisco based entrepreneur David Sneider invented it only within the last ten years. Although the new holiday was first celebrated on September 29, 2016, it was considered the 235th Galactic Tick Day. Curiouser and curiouser. How can the first commemoration of a holiday be so enumerated? Simply. Sneider and his cohorts designated October 2, 1608 as the 1st Galactic Tick Day. That was the date that Hans Lippershey, the Dutch lens maker who, unlike Galileo, actually invented the telescope, filed a patent for it. Sneider and his coterie of Galactic Tick enthusiasts reasoned that the telescope's invention enabled us to obtain the knowledge of the Milky Way Galaxy and its complex motions. Galactic Tick Days have scrolled rapidly by us during the ensuing centuries: every 633.7 days: one after the other after the other as the solar system zips merrily along its orbital path.
The date that Hans Lippershey (1570-1619) chose to file a patent for the telescope [October 2, 1608] has since been designated as the first "Galactic Tick Day."
On Saturday, September 9, 2023, we mark another milestone as the solar system shifts by another centi-arcsecond through the galaxy. As yet another sobering reminder of life's brevity and time's ephemerality, we note that the solar system has only moved by one arc-second since 1850! To place this time period in context, we mention that in 1850:
- Nathaniel Hawthorne published "The Scarlet Letter"
- San Francisco, the hometown of the Galactic Tick Day inventor, was incorporated as a city
- California, itself, was admitted as a US state
- President Millard Fillmore was inaugurated
- The first star -Vega- was photographed
- The University of Sydney, the oldest in Australia, was founded,
During this epoch (1850-2023) which saw the inventions of the telephone, television, motor cars, airplanes, radio, personal computers, and the various other amenities that displace us from the natural world, the Sun has merely moved merely one arc-second through the Milky Way Galaxy. [Another disquieting note: the solar system moves just one degree in 624,996 years.]
This Saturday, celebrate existence on Galactic Tick Day. If you miss it, you'll have another chance on June 4, 2025 and then again on March 9, 2027
Galactic Tick Day provides us an opportunity to pause and look outward, to acknowledge the celestial motions that inexorably continue despite the tumults and trivialities of our world.
*A yawning chasm of inextinguishable hellfire awaits the soul who produced the following image:
You see, we are looking at the Andromeda Galaxy, the nearest major spiral galaxy to our own. This graphic, indicating that our solar system is tucked away here, is similar to:
Rio de Janeiro, you are here.
**This used to be just a joke.
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