February 2025 Meeting Notes

Bartlesville Astronomical Society Meeting Notes

February 3, 2025

Attendance: 

We had 13 members and 4 visitors (including our guest speaker) in attendance this evening, in person and on Zoom.

Astronomical trivia—John G:

January trivia question—What would be the cloud cover on our intended night for a star party in January (January 11) at Jo Allyn Lowe Park?  The answer turned out to be 34%, and the closest guesses among our members were Evan at 25% and Pat at 43%.

This evening’s trivia:

·       Guessing the first asteroid spotted by spacecraft (Asteroid 951 Gaspra, Galileo spacecraft flyby, 1991)

·       How many minor planets have been visited by spacecraft (eighteen).  The eighteen includes Bennu and Arrokoth.

·       How many spacecraft are on their way to asteroids right now?  Five

Astronomy basics—Astronomy and Navigation—Gil:

Today’s GPS has an accuracy of about 1 meter.

Gil demonstrated how navigators before the days of GPS determined their location.

First, find Polaris, the North Star, via the Big Dipper star pointers.  If the Big Dipper is below the horizon, Polaris is half way between the constellations Ursa Major and Cassiopeia.

Once you find Polaris, you take a sextant reading of it.  That is your latitude.

You can do orienteering also on land.  Find a bright star and find an object to point to it; note where the star is in relation to your pointer object.  Then observe where the star is in relation to that pointer object over time.  In about half an hour, if the star goes up in relation to where it was before, you are facing east.  If the star goes down, you are facing west.  If the star goes left, you are facing north; if it goes right, you are facing south.

Main presentation:  The Copernicus Method, by Dan Zielinski

Dan has been the director of the Jenks Planetarium for 13 years.  He has worked with his students to produce planetarium shows of very high quality!

First, Dan gave us a planetarium show on a project of where the planets are in the night sky right now. 

·       Mercury’s apparent magnitude ranges from -2.48 to +7.25

·       Venus’ apparent magnitude ranges from -4.92 to -2.98.  Dan pointed out that Venus is the easiest planet to observe phases on, when a planet appears in crescent.  

·       Mars’ apparent magnitude ranges from -2.94 to +1.86.  Dan said that Mars is the easiest planet to observe when tracking retrograde motion. 

·       Jupiter’s apparent magnitude ranges from -2.94 to -1.66.  With Jupiter, you can track the motions of the four Galilean moons; two of those moons are bigger than planet Mercury, and they reflect a lot of light back to Earth.  Dan suggests looking at Jupiter’s moons 2-4 nights in a row to observe their motions as they orbit Jupiter.

·       Saturn’s apparent magnitude ranges from -0.55 to +1.17.  In November, after Saturn passes an equinox, we will see Saturn’s rings from below rather than from above. 

·       Uranus’ apparent magnitude ranges from +5.38 to +6.03. Uranus is rarely visible on Earth without equipment; our eyes can detect up to about +6.0 apparent magnitude.

·       Neptune’s apparent magnitude ranges from +7.67 to +7.89.  Must have equipment to view Neptune. 

In his planetarium shows, Dan teaches his students how you can find north using stars and the Sun; how you can tell time using the Sun (the Sun moves about 15 degrees every hour) and the Moon; and how you can tell the date with the stars and with the Sun.

The Copernicus Method:

Dan demonstrated how triangulation and trigonometry can be used to calculate the distance to planets from the Sun.  Using the planets’ eastern and western elongations in their orbits around the Sun; principles of right triangles; the known distance of Earth to the Sun (about 93 million miles, or one Astronomical Unit); and principles of trigonometry, he showed how you could calculate these distances.

Note:  At the time Copernicus lived, the actual distance between Earth and the Sun wasn’t known.  Copernicus’ method did result, however, in a scale model of the solar system with each planet’s orbital radius in terms of the Earth’s orbital radius.  For example, the orbital radius of Venus is roughly 0.7 of Earth’s orbital radius.

Recent Club Events:

·       The January 11 star party at Jo Allyn Lowe was cancelled due to winter weather.

·       The library display committee met January 18 to work on our March library display posters.

Upcoming Club Events:

·       February 15 - Public stargazing at Jo Allyn Lowe, weather permitting.  Two people at the meeting volunteered to bring optical telescopes if we do have a star party.

·       February 28 – We decided not to do a Club event for the full planetary alignment at Washington Park Mall.   Luann did say that we have permission to use the north area of the parking lot at the mall, but the lights have to be left on.

·       March – Our library display.  Setup beginning of March, takedown end March, dates TBD. 

Upcoming Astronomical Events:

·       Feb 6 - Moon passes in front of Pleiades in early morning hours, temporarily occulting many stars.

·       Feb 12 - Full Moon / Snow Moon

·       Feb 14 - Venus at its brightest (-4.6) in the western evening sky.

·       Feby 28 - The seven planets in alignment after sunset

Treasurer’s Report – Evan Z:

·       Dues are now overdue!

·       Ending balance December 31, 2024:  $17020.98

·       Deposit $130.00 in dues payments

·       Deposit $44.29 for Truity account interest

·       Expense for new thumb drive at Staples $19.59.

·       Ending balance January 31, 2025:  $17175.68

BAS needs volunteers:

Each monthly meeting includes a 5 to 10 minutes “Astronomy Basics” segment by a member about an astronomy topic they are interested in.  It doesn’t require expert knowledge, but rather a simple discussion of some aspect of astronomy.  Such a short segment is easy to research - Google and Wikipedia are your friends - easy to prepare and easy to discuss.  Please consider giving one of these presentations.  Maybe there is a topic that interests you, or something you’d like to learn more about.  One of the best ways to learn something is to teach it to someone else.  Once you’ve decided on a topic, contact one of the Club officers and let them know what you’d like to do. You will be contributing your knowledge and enthusiasm to the other members of BAS!

Reminders:

BAS has equipment, books, educational materials and scopes available for loan to qualifying members.