Home > Ephemeris Program, GTAS Outreach Event, Star Party > 07/22/2022 – Ephemeris – Saturday, weather permitting, there will be a star party at Sleeping Bear Dunes

07/22/2022 – Ephemeris – Saturday, weather permitting, there will be a star party at Sleeping Bear Dunes

July 22, 2022

This is Ephemeris for Pi Day number 2, Friday, July 22nd. Today the Sun will be up for 15 hours and 1 minute, setting at 9:19, and it will rise tomorrow at 6:19. The Moon, 2 days past last quarter, will rise at 2:01 tomorrow morning.

What’s Pi Day number 2? In the European way to write the date: 22 July or 22/7, the improper fraction that approximates pi, the ratio of the circumference of a circle to its diameter.

On to astronomical matters: Tomorrow night July 23rd there will be, weather permitting, a star party at Sleeping Bear Dunes National Lakeshore, this will take place at the Dune Climb. The star party is made possible by the rangers of the park and the Grand Traverse Astronomical Society. The society’s and member’s telescopes will take over the parking lot closest to the Dunes The event starts at 9 p.m., while it’s still light out and the location can be found. The park rangers will leave at 11, while the society members will stay longer.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). They may be different for your location.


Excerpt from the Sleeping Bear Dunes National Lakeshore calendar posting for August 23:

“These events will be cancelled if the sky is not visible due to weather conditions. The decision to cancel is usually made either three hours in advance or by 4:30 p.m. the day prior to the event. Please call park rangers at 231-326-4700, ext. 5005, for a voicemail message with the decision. For the early morning and late evening astronomy events, bring a flashlight for the walk to and from the event. Park rangers and GTAS staff will wear red glow bracelets at the events. For more information about the Grand Traverse Astronomical Society, go to http://www.gtastro.org/. “

Preparing to start the star party

Preparing to start a star party at the Dune Climb in a year before COVID. A few of the telescopes are visible, including the GTAS 25 inch “Emmettron” telescope at the far right. Credit: Eileen Carlisle.

Celestial events that night at the Dune Climb:

9:17 pm – Sunset (Sun will set behind the dune by around 8 pm)
9:57 pm – ISS* pass: highest 24° altitude in the north, moving from WNW to ENE.
10:00 pm – Brighter stars are visible. Telescopes can start to show the brighter binary stars.
10:20 pm – Saturn rises in the east-southeast. The sharpness of its image will improve as it rises higher in the sky.
10:33 pm – Nautical twilight ends. The brighter deep sky objects (DSOs**) become visible in telescopes. The Milky Way begins to show.
11:31 pm – ISS pass: highest 43° north-northeast, moving from NW to ENE
11:33 pm – Astronomical twilight ends. The sky is now completely dark.

* ISS – International Space Station. Start to look for it 2-3 minutes before this time. It will be at its brightest at its highest altitude.

** Deep Sky Objects – Telescopic objects beyond the solar system. They include star clusters, nebulae, and galaxies. Though that night, the only galaxy visible will be the Milky Way.

Click here for the definitions of the types of twilight.

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