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About UsThe Grand Traverse Astronomical Society is a nonprofit organization dedicated to to education and enjoyment of the night sky. Established in 1982, the GTAS has about 30 members from the Traverse City and the Grand Traverse area of northern Michigan. Meetings are held on the first Friday of every month beginning at 8 p.m. at Northwestern Michigan College's Joseph H. Rogers Observatory, though the August meeting is preempted by the annual picnic at another location. Guests are always welcome to our meetings. Over 750 attended the society sponsored Comet Hyakutake Watches March 23, and 24th, 1996. The farthest traveler came from Detroit to enjoy the dark skies and the spectacular comet through many telescopes. Comet Hale-Bopp attracted approximately 1,400 during the three scheduled viewing nights that were clear. We've hit the road, so to speak, with outreach beyond the NMC Observatory since 2007. Since 2011 we've held monthly star parties at Sleeping Bear Dunes National Lakeshore from April to October with additional eclipse and meteor shower watches. We bring our telescopes and exhibits to several festivals around the area along with Friday Night Live in Traverse City. Since 2010 the society has been hosting monthly star parties at the Sleeping Bear Dunes National Lakeshore.
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Upcoming Society Events Friday, November 7 – Monthly meeting and star party at NMC Rogers Observatory. Also available via Zoom. See below for instructions and a link. 7 PM – General Meeting, NMC Professor Jerry Dobek will explain about the Dark Skies Initiative, and how proper outdoor lighting is so important, not only for enjoying the dark skies, but also for getting around safely at night. 8 PM – Star Party, if it is clear. Special time! Friday, December 5 – Monthly meeting and star party at NMC Rogers Observatory. Also available via Zoom. See below for instructions and a link. 8 PM – General Meeting – Bob Moler continues his December ancient astronomy series: Ptolemy, the Good, Bad, and the Ugly. 9 PM – Star Party, if it is clear. Zoom Meeting Instructions: Link: https://us02web.zoom.us/j/8388913229?omn=86271806338
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ID: 838 891 3229
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ID: 838 891 3229 Check here often for other events that may pop up during the month. This article is distributed by NASA Night Sky Network
October’s Night Sky Notes: Let’s Go, LIGO! By Kat Troche September 2025 marks ten years since the first direct detection of gravitational waves as predicted by Albert Einstein’s 1916 theory of General Relativity. These invisible ripples in space were first directly detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO). Traveling at the speed of light (~186,000 miles per second), these waves stretch and squeeze the fabric of space itself, changing the distance between objects as they pass.Waves In SpaceGravitational waves are created when massive objects accelerate in space, especially in violent events. LIGO detected the first gravitational waves when two black holes, orbiting one another, finally merged, creating ripples in space-time. But these waves are not exclusive to black holes. If a star were to go supernova, it could produce the same effect. Neutron stars can also create these waves for various reasons. While these waves are invisible to the human eye, this animation from NASA’s Science Visualization Studio shows the merger of two black holes and the waves they create in the process.
Two black holes orbit around each other and generate space-time ripples called gravitational waves in this image. Credit: NASA's Goddard Space Flight Center Conceptual Image Lab How It WorksA gravitational wave observatory, like LIGO, is built with two tunnels, each approximately 2.5 miles long, arranged in an "L" shape. At the end of each tunnel, a highly polished 40 kg mirror (about 16 inches across) is mounted; this will reflect the laser beam that is sent from the observatory. A laser beam is sent from the observatory room and split into two, with equal parts traveling down each tunnel, bouncing off the mirrors at the end. When the beams return, they are recombined. If the arm lengths are perfectly equal, the light waves cancel out in just the right way, producing darkness at the detector. But if a gravitational wave passes, it slightly stretches one arm while squeezing the other, so the returning beams no longer cancel perfectly, creating a flicker of light that reveals the wave’s presence.
Still images of how LIGO (Laser Interferometer Gravitational-Wave Observatory) detects gravitational waves using a laser, mirrors, and a detector. You can find the animated version here. Image Credit: NASA (To view image in actual size, click or right click on the image and select Open image in new Tab) The actual detection happens at the point of recombination, when even a minuscule stretching of one arm and squeezing of the other changes how long it takes the laser beams to return. This difference produces a measurable shift in the interference pattern. To be certain that the signal is real and not local noise, both LIGO observatories — one in Washington State (LIGO Hanford) and the other in Louisiana (LIGO Livingston) — must record the same pattern within milliseconds. When they do, it’s confirmation of a gravitational wave rippling through Earth. We don’t feel these waves as they pass through our planet, but we now have a method of detecting them!Get InvolvedWith the help of two additional gravitational-wave observatories, VIRGO and KAGRA, there have been 300 black hole mergers detected in the past decade; some of which are confirmed, while others await further study. While the average person may not have a laser interferometer lying around in the backyard, you can help with two projects geared toward detecting gravitational waves and the black holes that contribute to them:
You can also use gelatin, magnetic marbles, and a small mirror for a more hands-on demonstration on how gravitational waves move through space-time with JPL’s Dropping In With Gravitational Waves activity!
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LinksFor Kids: NASA’s Space Place website The Space Place is a NASA website for elementary school-aged kids, their teachers, and their parents.
It has over 150 separate modules for kids, including hands-on projects, interactive games, animated cartoons, and amazing facts about space and Earth science and technology. See this month's NASA Night Sky Network article at the bottom of the center panel on this page. Also check out these two sites for kids: NASA's Climate Kids and NOAA's SciJinks Bob Moler's Ephemeris contains audio mp3s of current Ephemeris programs; calendars of sunrise, sunset, moonrise and moonset for the Grand Traverse area of Michigan, and other locations in northern Michigan; plus a monthly star chart. Also Bob's Ephemeris Blog with daily transcripts of and illustrations for his Ephemeris programs on Interlochen Public Radio. Wednesday’s program looks at where the bright planets are along with finder charts. Northwestern Michigan College's Joseph H. Rogers Observatory If you'd like to donateFrom Article II, B of the Articles of Incorporation of the Grand Traverse Astronomical Society: The Society shall operate a scientific and educational organization with the goal of increasing interest in, the knowledge and enjoyment of astronomy; cooperate with similar organizations; and cooperate with Northwestern Michigan College to increase the benefit of the college observatory to the community. As you can see by the statement above the society is inexorably linked to the Joseph H. Rogers observatory. However in the past number of years members have been also taking telescopes out into the community, on sidewalks and street corners, and in the street on Friday Night Live, and to the Sleeping Bear Dunes National Lakeshore. We find that many folks in the area have never been out to the observatory. This way we are going to to the public. And having a huge telescope is really a great attraction, not to mention the superb views of the heavens it will provide. We have purchased a 25 inch Dobsonian telescope with trailer to use and to take around for our outreach program. We have also purchased two solar telescopes to view the Sun's prominences and chromosphere. We have recently purchased small telescopes to give to libraries for them to lend out. The first two recipients are Traverse Area District Library and Betsie Valley District Library. Enerdyne of Suttons Bay donated the second telescope.. You may contribute to the fund to help us upgrade and add accessories to the society's telescopes by mailing a check to the GTAS, c/o the society treasurer Gary Carlisle, 1473 Birmley Rd, Traverse City, MI 49686. We are a 501(c)(3) non profit organization. Donations are tax deductible.
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