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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.

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

Two of our members are also NASA/JPL Solar System Ambassadors.

Upcoming Society Events

Note: Meeting from May through July will start an hour later at 9 PM.

Friday, June 6 – Monthly meeting and star party at NMC Rogers Observatory. Also available via Zoom. See our website http://www.gtastro.org. for instructions and a link.

9 PM – General Meeting

10 PM – Star Party, if it is clear.

Friday, July 11 – (Postponed one week due to July 4th holiday) Monthly meeting and star party at NMC Rogers Observatory. Also available via Zoom. See our website http://www.gtastro.org for instructions and a link.

9 PM – General Meeting: Joe Brooks will present a program on meteorites.

10 PM – Star Party, if it is clear.

No meeting in August.

Friday, September 5 – Monthly meeting and star party at NMC Rogers Observatory. Also available via Zoom. See our website http://www.gtastro.org. for instructions and a link.

8 PM – General Meeting: Dan Dall’Olmo, who has taken some amazing astrophotographs, will present the program

9 PM – Star Party, if it is clear.

Zoom Meeting Instructions:

Link: https://us02web.zoom.us/j/8388913229?omn=86271806338

Meeting ID: 838 891 3229
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Meeting ID: 838 891 3229

Find your local number:
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Check here often for other events that may pop up during the month.

Star parties at the Sleeping Bear National Lakeshore are expected to resume in late spring 2025.


This article is distributed by NASA Night Sky Network

The Night Sky Network program supports astronomy clubs across the USA dedicated to astronomy outreach. Visit nightsky.jpl.nasa.gov to find local clubs, events, and more!


June’s Night Sky Notes: Seasons of the Solar System

By: Kat Troche



Uranus rolls on its side with an 84-year orbit and a tilt just 8° off its orbital plane. Its odd tilt may be from a lost moon or giant impacts. Each pole gets 42 years of sunlight or darkness. Voyager 2 saw the south pole lit; now Hubble sees the north pole facing the Sun. Credit: NASA, ESA, STScI, Amy Simon (NASA-GSFC), Michael Wong (UC Berkeley); Image Processing: Joseph DePasquale (STScI)


Here on Earth, we undergo a changing of seasons every three months. But what about the rest of the Solar System? What does a sunny day on Mars look like? How long would a winter on Neptune be? Let’s take a tour of some other planets and ask ourselves what seasons might look like there.


Martian Autumn


Although Mars and Earth have nearly identical axial tilts, a year on Mars lasts 687 Earth days (nearly 2 Earth years) due to its average distance of 142 million miles from the Sun, making it late autumn on the red planet. This distance and a thin atmosphere make it less than perfect sweater weather. A recent weather report from Gale Crater boasted a high of -18 degrees Fahrenheit for the week of May 20, 2025.




An artist's greatly exaggerated rendition of Mars’ orbit around the Sun, and its seasons. Credit: NASA/JPL-Caltech

Seven Years of Summer


Saturn has a 27-degree tilt, very similar to the 25-degree tilt of Mars and the 23-degree tilt of Earth. But that is where the similarities end. With a 29-year orbit, a single season on the ringed planet lasts seven years. While we can’t experience a Saturnian season, we can observe a ring plane crossing here on Earth instead. The most recent plane crossing took place in March 2025, allowing us to see Saturn’s rings ‘disappear’ from view.


A Lifetime of Spring



NASA Hubble Space Telescope observations in August 2002 show that Neptune's brightness has increased significantly since 1996. The rise is due to an increase in the amount of clouds observed in the planet's southern hemisphere. Credit: NASA, L. Sromovsky, and P. Fry (University of Wisconsin-Madison)


Even further away from the Sun, each season on Neptune lasts over 40 years. Although changes are slower and less dramatic than on Earth, scientists have observed seasonal activity in Neptune’s atmosphere. These images were taken between 1996 and 2002 with the Hubble Space Telescope, with brightness in the southern hemisphere indicating seasonal change.


As we welcome summer here on Earth, you can build a Suntrack model that helps demonstrate the path the Sun takes through the sky during the seasons. You can find even more fun activities and resources like this model on NASA's Wavelength and Energy activity. 


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 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 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: 10:34:27 PM 05/29/25