Planet Watch: Jupiter Returns! — Framework Notes (started 2026-10-25; date moved same day)

Series: Planet Watch. Publication: 2027-01-10 (Sun). (Moved from 2026-12-27: Jupiter wasn’t really an evening object yet.) Mars Returns follows on 2027-02-07. Workflow step: 1. Short piece. [verify] = check before prose.

Computed (astropy, 2026-10-25, North Adams)

  • Jupiter in Leo all season. Opposition ≈ 2027-02-10/11 (astropy peak elongation 178.9° on Feb 11 00h UT = Feb 10 evening EST; JOA/Arlot table says Feb 11; Cambridge calendar lists Feb 10). Use “February 10–11” or settle with Horizons.
  • Jan 10 (publication): rises 7:31 PM EST; 16° at 9 PM; transits 2:23 AM at 61°; distance 4.51 AU.
  • Evening progress (9 PM EST altitude): Jan 15 20° · Jan 21 25° · Jan 28 31° · Feb 4 37°. Rise times: Jan 15 7:09 PM · Jan 21 6:42 PM · Jan 28 6:10 PM · Feb 4 5:38 PM.
  • Feb 10: 4.36 AU (closest this apparition).
  • Mars is also in Leo, trailing Jupiter by ~3 weeks (rises ~1 h later in January). One line here pointing ahead to “Mars returns” is fine as plain text; no link until it’s published.

Verified

  • Jovian equinox 2026-12-16; mutual events of the Galilean satellites run May 2026 – Aug 2027; most eclipses Oct 2026 – Jan 2027 (BAA Computing Section; IMCCE PHEMU campaign; Arlot, Journal for Occultation Astronomy 2026-3). Observable events continue to ~June 2027 (NSDC MULTI-SAT).

Hook

“Returns” = back in the evening sky: by mid-January it’s up by early evening and climbing every week toward opposition. This apparition has a bonus the last few didn’t: we’re looking edge-on to the moons’ orbits, so the moons eclipse and occult each other — something you only get about every 6 years (twice per 12-year orbit).

Sections (short)

  1. Where and when: Leo, rising early evening, better each week to opposition Feb 10–11.
  2. Why now is special: Jupiter’s equinox → mutual events. One-paragraph explanation + a table of 2–4 well-placed events for North Adams, Jan 10 – Feb [compute from IMCCE/ NSDC MULTI-SAT ephemerides; filter Jupiter alt > 20°, Sun < −12°]. Note that the best eclipse season is winding down — catch them in January.
  3. What a small scope shows: belts, GRS (transit times — Sky & Telescope / JUPOS [verify]), moon transits and shadow transits (shadows land close to the moons near equinox [verify]).
  4. Smart scope: time-lapse of a mutual event; brightness drop measurable? (BAA/IMCCE ask for observations — real citizen science) [verify how they want data submitted].
  5. Opposition preview: Feb 10–11, size ~45″ [verify]. No forward links.

Cautions

  • Mutual-event times: give UT and EST, state they’re predictions, give the source.
  • Don’t overstate visibility: many events are minutes-long and need a telescope; eclipses are easier than occultations (BAA).

Figures

  • fig-jupiter-mutual-geometry: why the moons line up near equinox (schematic).
  • Possibly fig-jupiter-evening (Jan–Feb altitude at 9 PM EST, Jupiter and Mars).
  • Bob’s Jupiter image(s) for banner/thumbnail.

Open questions for Bob

  1. Include an event table (more work, more useful), or link out to IMCCE/BAA?
  2. Any of your own mutual-event or shadow-transit captures from 2021?

Cross-references

smart-scope-gift (Dec 24 — published before this, so it can’t link here), mars-returns (Feb 7), earlier Planet Watch / Jupiter articles (7 cover Jupiter per the taxonomy count).