Jovian for Palm OS: Observing Jupiter and Its Moons on a Palm Handheld



During the Palm OS era, a small category of dedicated astronomy utilities let observers carry planetarium-style calculations in a shirt pocket. Jovian, developed by Hans Anger and distributed through his site astro-metrics.com and through PalmGear, was one of the more specialized entries in that category: rather than plotting the whole night sky, it focused entirely on Jupiter — its four largest moons and its Great Red Spot. This page restores what can be verified about Jovian from surviving archived sources, including the astro-metrics.com developer site captured by the Wayback Machine and a contemporary astronomy-club article that cited PalmGear product ID 6343 directly.

What Was Jovian?

Jovian was a Palm OS observing utility built around a single planet. Its own promotional copy, preserved on multiple Wayback Machine snapshots of astro-metrics.com between 2002 and 2005, described it this way: "Observe Jupiter's four largest moons, also known as the Galilean Satellites, after Galileo Galilei, who first discovered and observed them in 1610, and Jupiter's Great Red Spot (GRS)... Jovian helps you to easily locate and identify the moons and lets you animate their orbits around our solar system's largest gas giant. Further screens show you the position of the GRS for any given time and date within the Palm's date range, and the different zones and belts in Jupiter's atmosphere with their names."

Unlike general-purpose planetarium software such as Planetarium or PleiadAtlas — which also appeared on PalmGear's astronomy shelf during the same period — Jovian was not designed to chart the whole sky. It was a purpose-built companion for one specific observing task: figuring out, for a chosen date and time, where Io, Europa, Ganymede, and Callisto sat relative to Jupiter, whether the Great Red Spot would be facing Earth, and which belts and zones an observer should expect to see in the planet's cloud tops.

The Galilean Moons: Why Their Positions Matter

Jupiter's four largest moons — Io, Europa, Ganymede, and Callisto — are collectively known as the Galilean satellites after Galileo Galilei, who observed them in January 1610. All four are bright enough to be seen with ordinary binoculars or a small telescope, but because they orbit Jupiter on timescales ranging from roughly 1.8 days (Io) to about 16.7 days (Callisto), their apparent arrangement around the planet changes visibly from night to night, and sometimes hour to hour. An observer looking through an eyepiece has no way to know, unassisted, which point of light is which moon, or whether a "missing" moon is simply in transit in front of Jupiter, hidden behind it, or in Jupiter's shadow. A calculation tool that could plot each moon's position for a specific date and time — and animate that motion — solved a real, recurring problem for backyard Jupiter watchers. That is the gap Jovian was built to fill.

Developer and Origins: Hans Anger and astro-metrics.com

Archived astro-metrics.com pages consistently list Hans Anger as the author, both in HTML meta-author tags ("Author: Hans Anger") on the site's homepage and product pages, and via a contact address (hans.a@virgin.net) on an earlier, pre-astro-metrics.com version of the site hosted at freespace.virgin.net/hans.a/ — a UK ISP's personal-homepage service. That earlier freespace.virgin.net page, archived by December 2001, already displayed a "Jovian" icon in its software list, alongside two other titles, Orrery and Lunar.

Jovian's earliest confirmed commercial listing found in this research is a Wayback Machine capture from August 29, 2000, of a product page on Yahoo Store under the merchant name "pilotgearsw" ("Pilot Gear SW"). That page already used the "Jovian" name and already described Great Red Spot tracking, and its checkout form's hidden order-fulfillment address was PalmGear's own Arlington, Texas office — indicating Jovian was, at that point, being sold through a PalmGear-affiliated storefront in addition to (or instead of) a direct developer site. The internal order-form item code for Jovian on that page was GALSAT, which is suggestive of an earlier working title related to "Galilean Satellites," though no archived page actually uses that as a product name — this is an inference from the checkout code, not a confirmed former title, and should be treated as such.

Note: No archived snapshot found in this research predates the "Jovian" branding, so an exact first-release date could not be verified. The version history published on astro-metrics.com (below) shows three releases — 1.0, 1.0.1, and 1.5 — before the "Jovian" rename at version 2.0, which had already occurred by August 2000. A precise calendar date for version 1.0 is not available from surviving sources.

Version History

The most complete version history found is the changelog published on astro-metrics.com's Jovian page, consistent across Wayback Machine captures from October 2002 through April 2005. It runs as follows, oldest to newest:

Version 2.6.4 is the last version confirmed by archived sources — it is listed as current on both the Jovian product page and the "astro-metrics bundle" page as of an April 2005 capture. Real product content on astro-metrics.com continues to appear in Wayback Machine snapshots through at least August 2007; by 2010–2011 the domain had lapsed into a generic parked-domain page, and no further Jovian version changes were found after 2.6.4. Whether any later version was ever released could not be verified.

Screens and Features

Jovian's developer page described four main screens, each documented with a short caption and a small looping preview animation. The following is drawn directly from that documentation.

The Moons and Orbital View

"On the moons screen the top half of the screen shows you the positions of the moons around Jupiter as you would see them through binoculars or a telescope. The lower half has an orbital view with a direction indicator to clarify whether a moon is in front or behind Jupiter (keep in mind that the North direction always indicates the half of the orbit which is behind Jupiter). Tapping the direction indicators switches the orientation to accommodate for viewing through different telescopes and binoculars. Tapping on a moon displays its name at the top of the screen."

In other words, Jovian offered both a "what you'd see at the eyepiece" view and a schematic orbital diagram side by side, plus a toggle to flip the orientation to match different optical setups — useful because binoculars, refractors, and reflectors (with or without a star diagonal) can each present a mirrored or rotated field of view relative to the naked-eye sky.

The Great Red Spot Screen

"The GRS screen shows you the location of the GRS and the Central Meridian longitudes for System I and System II of Jupiter's atmosphere. The bar below Jupiter shows the location when the GRS is on the far side." This screen let an observer check, for a chosen date and time, whether the Great Red Spot would be facing Earth (i.e., near the Central Meridian) or rotated out of view on the planet's far side — information useful for planning a Great Red Spot transit observation in advance.

Note: The Great Red Spot's longitude drifts over months and years (it has drifted substantially over the decades astronomers have tracked it), so any positional calculation baked into a piece of software last updated around 2004–2005 (version 2.6.4) will not reflect the Great Red Spot's actual current longitude. This restored page documents what Jovian did and how it worked during the Palm OS era — it is not a claim that Jovian's Great Red Spot predictions remain accurate for present-day observing. Anyone trying to plan a real Great Red Spot transit today should use current data, not a 20-year-old Palm application.

Zones and Belts of Jupiter's Atmosphere

"This screen shows the different lighter zones and darker belts in Jupiter's atmosphere with their abbreviations. Tapping on an abbreviation gives the full name at the bottom of the display." This feature was added at version 2.5, according to the version history table above, alongside "nicer support for colour and grey scale."

Info Screens

"The info (i) button on either the orbital, zones or GRS screen calls up a window with informational texts and statistics of the moons and the GRS." An earlier information screen specifically about the Galilean satellites was already present as of version 1.5, before the Great Red Spot and zones/belts features existed.

Device Compatibility and Requirements

Astro-metrics.com's own compatibility statement changed wording slightly over time but stayed consistent in substance. In an October 2002 snapshot: "Jovian is available for all b/w, grey scale and colour Palm OS devices with Palm OS 2.0 or greater." By April 2005, the wording had narrowed to a stated ceiling: "Jovian is available for all b/w, grey scale and colour Palm OS devices with Palm OS 2.0 through to Palm OS 5," accompanied by an "OS 5 Ready" badge graphic. Combined with the version-history entries for 2.6.2 (a HandEra 330–specific bug fix) and 2.6.3 (Palm OS 5 compatibility), this indicates Jovian was actively tested against — and patched for — a fairly wide spread of real Palm OS hardware over its lifetime.

Note: Because Palm OS 5 devices spanned a wide range of screen resolutions and color depths, and because Jovian's own copy never states specific pixel dimensions, this page does not claim Jovian supported any particular resolution beyond the general "b/w, grey scale and colour" language the developer used.

Pricing, Licensing, and Localization

Jovian was commercial shareware, not freeware, throughout the period documented here. Pricing varied by storefront and by year:

The software's promotional text explicitly asked users to "Please support shareware," and separate registration links pointed to PalmGear's own storefront in addition to the developer's direct store, consistent with typical PalmGear-era registerware distribution: a free trial download plus a paid unlock. Currently, a "pre-registered" (i.e., already unlocked) version is redistributed for free through the preservation site PalmDB, credited to a rehoster ("Subvert," from a community called C4PDA.net) rather than the original developer — this reflects the software's abandonware status today, not its original commercial terms.

Jovian and the astro-metrics Family

Jovian was one of four related Palm OS titles Hans Anger published under the "astro-metrics" banner, sold individually or as a discounted bundle:

• Lunar — a Moon-phase application showing lunar phase, orbital position, distance from Earth, age in the current lunation, percentage illumination, named lunar features, and the ability to add major Moon phases to the Palm Date Book.
• Orrery — displayed the orbital positions of the nine planets (as classified at the time) around the Sun, with animation to visualize elongations of Mercury and Venus and oppositions of the outer planets.
• Jovian — the Jupiter-focused tool documented on this page.
• astro-metrics DA — a Desk Accessory (callable from within other running applications) showing local and Universal date/time, Greenwich and Local Mean Sidereal Time, and the Julian Day and Modified Julian Day, with direct links to switch between the other astro-metrics applications.

By the "astro-metrics bundle" version 1.2 (documented on a February 2005 capture), the bundle shipped Lunar 1.9, Jovian 2.6.4, Orrery 2.4, and astro-metrics DA 1.1, and was billed as "fully Palm OS 5 compatible."

PalmGear Listing and the Historical Record

The historical PalmGear product page for Jovian — http://palmgear.com/software/showsoftware.cfm?sid=54905620021122082656&prodID=6343 — is not itself present in the Wayback Machine; PalmGear's dynamic, session-ID-bearing product pages generally were not archived, and this one is no exception. However, that exact URL, and the exact product ID 6343, is independently confirmed by a dated third-party source: a "Computers in Astronomy" column by Don Shedrick, part of a December 2002 "DAS Focus" newsletter piece (dated November 22, 2002) surveying Palm OS astronomy software, archived on a University of Delaware personal web page. That article lists Jovian as "the all in one observing tool for Jupiter, helping you to easily locate and identify the moons in their orbits, the Great Red Spot's position, and the different zones and belts in Jupiter's atmosphere with their names, all for any given time and date within the Palm's date range," links directly to the PalmGear URL with prodID=6343, and separately links to "http://www.astro-metrics.com/Jovian.html" as the developer's own page — matching this page's other sources. The same article is useful for context: it explicitly distinguishes Jovian from two other Palm planetary tools, Mars2001 and SatMoons, both of which it credits to a different developer, Akkana Peck, ruling out any confusion between the two authors' work.

Because no archived PalmGear page for Jovian survives, no PalmGear-specific release date, user rating, review count, or exact listed price on PalmGear itself could be verified. Only the developer's own site and this third-party citation could be confirmed.

Why Observers Used Jovian

Taken together, the verified feature set explains why a dedicated observer might have carried Jovian to the eyepiece rather than relying on memory or a printed almanac: it let a user dial in tonight's date and time and immediately see which of Io, Europa, Ganymede, or Callisto should be visible and on which side of Jupiter; it flagged whether the Great Red Spot would be facing Earth or hidden on the planet's far side, useful for timing a transit-watching session; it labeled the atmospheric belts and zones an observer might be trying to identify visually; and its orientation toggle meant the same schematic could be read correctly whether the user was looking through a straight-through refractor, a mirror-reversed reflector, or ordinary binoculars. For someone planning an observing session around a specific moon configuration, an upcoming transit, occultation, or eclipse event among the Galilean moons, or Great Red Spot visibility, a purpose-built calculator like this removed the need to work out those geometries by hand.

Note: Surviving sources describe Jovian's orbital and Great Red Spot displays in general terms but do not spell out, in the material found for this research, a dedicated "predicted transit/occultation/eclipse event list" feature as a labeled function distinct from the moons and orbital screens described above. This page does not claim Jovian included such an event-list feature beyond what is documented in the "Screens and Features" section.

Where Jovian Survives Today

astro-metrics.com, the original developer site, no longer hosts Jovian. Wayback Machine captures show the domain functioning normally with real Jovian content through at least 2007–2008, but by the early 2010s (and in the most recent capture found, from 2026) it had become a generic parked/domain-for-sale page unrelated to the original software. The eSellerate storefront link used for original purchases (store.esellerate.net) is likewise defunct. As of this research, a "pre-registered" (already unlocked) build of Jovian — separate color and black-and-white/greyscale program files plus a documentation archive — is hosted on the Palm software preservation site PalmDB, submitted by a third-party archivist rather than the original developer. This reflects the current abandonware status of the title rather than any ongoing support from Hans Anger or astro-metrics.com.

Frequently Asked Questions

Key Takeaways

• Jovian was a Palm OS utility dedicated to observing Jupiter: its four Galilean moons (Io, Europa, Ganymede, Callisto), the Great Red Spot, and Jupiter's atmospheric belts and zones.
• It was developed by Hans Anger and distributed via his site, astro-metrics.com, and via PalmGear under product ID 6343 (historical URL confirmed by an independent, dated November 2002 astronomy-club citation).
• Documented version history runs from 1.0 (first public release) through 2.6.4 (the last version confirmed by archived sources, adding Palm OS 3.5-and-below crash fixes); the "Jovian" name and Great Red Spot feature were both added at version 2.0, which had already shipped by August 2000.
• It supported black-and-white, greyscale, and color Palm OS devices from Palm OS 2.0 through Palm OS 5, with a specific fix documented for the HandEra 330; Sony CLIÉ support was never confirmed in any source found.
• It was commercial shareware, priced at $10–$11.99 depending on storefront and year, and was also sold bundled with three sibling titles (Lunar, Orrery, astro-metrics DA) for $35.95.
• Its Great Red Spot and Central Meridian calculations reflect data current only as of its last update (circa 2004–2005) and should not be treated as accurate for present-day observing.
• The original developer site and store are defunct; a pre-registered build is currently redistributed by third-party archivists via the preservation site PalmDB, not by the original developer.