Check out the link above for our 2020 Outreach Schedule. Always a work in progress, check often.

About Us

The 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, and beginning in 2016 at the Arcadia Dunes.

The GTAS belongs to the International Dark-Sky Association and participates in Project Astro.

We also participate in the annual International Observe the Moon Night.

Upcoming Meetings and Outreach Events

Note that outdoor events are held weather permitting

Due to the Coronavirus (COVID-19) GTAS meetings and star parties at the NMC Observatory have been canceled until further notice. Events at the Sleeping Bear Dunes National Lakeshore will be evaluated with the park rangers as we go forward.

September 11, 2020 9 p.m. Virtual star party on the Internet via Zoom

How to connect:

From a computer: https://nmc.zoom.us/j/6436305037?pwd=QVQvenZBWW52VE80Q3J2V1JseFpBdz09 (The Zoom app will be installed if it hasn’t been before. It’s free)





This article is distributed by NASA Night Sky Network

The Night Sky Network program supports astronomy clubs across the USA dedicated to astronomy outreach



Summer Triangle Corner: Deneb

David Prosper

The Summer Triangle is high in the sky after sunset this month for observers in the Northern Hemisphere, its component stars seemingly brighter than before, as they have risen out of the thick, murky air low on the horizon and into the crisper skies overhead. Deneb, while still bright when lower in the sky, now positively sparkles overhead as night begins. What makes Deneb special, in addition to being one of the three points of the Summer Triangle? Its brilliance has stirred the imaginations of people for thousands of years!

Deneb is the brightest star in Cygnus the Swan and is positioned next to a striking region of the Milky Way, almost as a guidepost. The ancient Chinese tale of the Cowherd (Niulang) and the Weaver Girl (Zhinü) - represented by the stars Altair and Vega - also features Deneb. In this tale the two lovers are cast apart to either side of the Milky Way, but once a year a magical bridge made of helpful magpies – marked by Deneb – allows the lovers to meet. Deneb has inspired many tales since and is a staple setting of many science fiction stories, including several notable episodes of Star Trek.

Astronomers have learned quite a bit about this star in recent years, though much is still not fully understood – in part because of its intense brightness. The distance to Deneb from our Sun was measured by the ESA’s Hipparcos mission and estimated to be about 2,600 light years. Later analysis of the same data suggested Deneb may be much closer: about 1,500 light years away. However, the follow-up mission to Hipparcos, Gaia, is unable to make distance measurements to this star! Deneb, along with a handful of other especially brilliant stars, is too bright to be accurately measured by the satellite’s ultra-sensitive instruments.

Deneb is unusually vivid, especially given its distance. Generally, most of the brightest stars seen from Earth are within a few dozen to a few hundred light years away, but Deneb stands out by being thousands of light years distant! In fact, Deneb ranks among the top twenty brightest night time stars (at #19) and is easily the most distant star in that list. Its luminosity is fantastic but uncertain, since its exact distance is also unclear. What is known about Deneb is that it’s a blue-white supergiant star that is furiously fusing its massive stocks of thermonuclear fuel and producing enough energy to make this star somewhere between 50,000 and 190,000 times brighter than our Sun if they were viewed at the same distance! The party won’t last much longer; in a few million years, Deneb will exhaust its fuel and end its stellar life in a massive supernova, but the exact details of how this will occur, as with other vital details about this star, remain unclear.

Discover more about brilliant stars and their mysteries at nasa.gov.

Long exposure shot of Deneb (brightest star, near center) in its richly populated Milky Way neighborhood. Photo credit: Flickr user jpstanley. Source: https://www.flickr.com/photos/jpstanley/1562619922 License: https://creativecommons.org/licenses/by-nc-sa/2.0/

Spot Vega and the other stars of the Summer Triangle by looking straight up after sunset in August!


Summer Triangle Corner: Altair

David Prosper

Altair is the final stop on our trip around the Summer Triangle! The last star in the asterism to rise for Northern Hemisphere observers before summer begins, brilliant Altair is high overhead at sunset at the end of the season in September. Altair might be the most unusual of the three stars of the Triangle, due to its great speed: this star spins so rapidly that it appears “squished.”

A very bright star, Altair has its own notable place in the mythologies of cultures around the world. As discussed in our previous edition, Altair represents the cowherd Niulang in the ancient Chinese tale of the “Cowherd and the Weaver Girl.” Altair is the brightest star in the constellation of Aquila the Eagle; while described as part of an eagle by ancient peoples around the Mediterranean, it was also seen as part of an eagle by the Koori people in Australia! They saw the star itself as representing a wedge-tailed eagle, and two nearby stars as his wives, a pair of black swans. More recently one of the first home computers was named after the star: the Altair 8800.

Altair’s rapid spinning was first detected in the 1960s. The close observations that followed tested the limits of technology available to astronomers, eventually resulting in direct images of the star’s shape and surface by using a technique called interferometry, which combines the light from two or more instruments to produce a single image. Predictions about how the surface of a rapidly spinning massive star would appear held true to the observations; models predicted a squashed, almost “pumpkin-like” shape instead of a round sphere, along with a dimming effect along the widened equator, and the observations confirmed this! This equatorial dimming is due to a phenomenon called gravity darkening. Altair is wider at the equator than it is at the poles due to centrifugal force, resulting in the star’s mass bulging outwards at the equator. This results in the denser poles of the star being hotter and brighter, and the less dense equator being cooler and therefore dimmer. This doesn’t mean that the equator of Altair or other rapidly spinning stars are actually dark, but rather that the equator is dark in comparison to the poles; this is similar in a sense to sunspots. If you were to observe a sunspot on its own, it would appear blindingly bright, but it is cooler than the surrounding plasma in the Sun and so appears dark in contrast.

As summer winds down, you can still take a Trip Around the Summer Triangle with this activity from the Night Sky Network. Mark some of the sights in and around the Summer Triangle at: bit.ly/TriangleTrip. You can discover more about NASA’s observations of Altair and other fast and furious stars at nasa.gov.

The image on the right was created using optical interferometry: the light from four telescopes was combined to produce this image of Altair’s surface. Image credit: Ming Zhao. More info: bit.ly/altairvsmodel

Altair is up high in the early evening in September. Note Altair’s two bright “companions” on either side of the star. Can you imagine them as a formation of an eagle and two swans, like the Koori?


Links

For Kids: NASA’s Space Place website

The Space Place is a NASA website for elementary school-aged kids, their teachers, and their parents.

It’s colorful!
It’s dynamic!
It’s fun!

It’s rich with science, technology, engineering, and math (STEM) content!

It’s informal. It’s meaty. It’s easy to read and understand. It’s also in Spanish. And it’s free!

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 donate

From 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 feature a solar viewing time at the Sleeping Bear Dunes before the star parties in June, July and August.

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.

Thank You!

Updated: 09/11/20 08:39:46 PM