Episode 219

In this episode of the Observers Notebook podcast, host Tim Robertson talks to Bob Lunsford about his process for observing and photographing the recent transits of Saturn’s moon Titan.

Titan’s Orbit and Motion:

• Orbital period around Saturn: ~15.945 Earth days

• Average distance from Saturn: ~1.22 million km

• Orbital inclination: ~0.3° relative to Saturn’s equator (small, so Titan’s path is nearly aligned with Saturn’s rings).

• Apparent size: ~0.8 arcseconds (tiny, only detectable as a “point” in most telescopes).

• Shadow transits are possible only when Saturn’s rings are edge-on (every ~15 years).

• September 20, 2025 — Start around 5:09 AM UTC (≈10:09 PM PDT); ends ~7:34 AM UTC (~12:34 AM PDT); Titan may also be visible near its shadow.

• After October 5–6, 2025, this spectacular phenomenon won’t happen again until 2038–2039.

You can contact Bob at:

Stellarium

https://stellarium.org/

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www.alpo-astronomy.org/

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I want to thank the Producers of this podcast, Steve Siedentop and Michael Moyer for their generous support of the Observers Notebook.

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