{"id":42721,"date":"2026-10-01T09:23:54","date_gmt":"2026-10-01T13:23:54","guid":{"rendered":"https:\/\/wading-in.net\/walkabout\/?p=42721"},"modified":"2026-10-01T09:23:54","modified_gmt":"2026-10-01T13:23:54","slug":"set-that-alarm","status":"publish","type":"post","link":"https:\/\/wading-in.net\/walkabout\/2026\/10\/set-that-alarm\/","title":{"rendered":"Set that alarm"},"content":{"rendered":"

\"Stellarium
Coming up on October 6th<\/sup> at roughly 08:15 UTC (which translates to 4:15 AM Eastern Daylight Time,) the crescent moon will occult Jupiter – for once, a nice target for an occultation, since it’s a planet and, at decent magnification, has both a shape and detail. Note that this is for North America and may not occur (or be hidden below the horizon) for many other locations, so check carefully. The four Galilean moons (Callisto, Europa, Ganymede, & Io) will be lined up to disappear in an orderly fashion as well, but much better, they’ll all reappear at roughly 09:17 UTC (5:17 AM EDT) from the dark, non-crescent side, so the light from the moon won’t be overpowering the exposures and you might even catch some earthshine delineating the edge of the moon as the first of the Galilean moons appear.<\/p>\n

As always, best to check with Stellarium to confirm exactly when this will occur for your area, because it will vary – the movement is all along the plane of the ecliptic, but the moon is a wee<\/em> bit closer to us than Jupiter, so the precise timing really does depend on where on the planet (Earth this time) you’re watching. Also remember, while the general motion of all celestial bodies is East-to-West, the moon is orbiting on its own, making it appear slower than the other bodies;<\/strong> thus, Jupiter will overtake it from behind, and peek out ahead as it reappears, so plan and frame accordingly.<\/p>\n

In fact, if you have a telescope and tracking motor set to standard motion, Jupiter will remain ‘motionless’ while the moon slowly covers it from West to East, or moving down and slightly left when watching from a North American location. If your tracking is set for lunar motion, however, these will be reversed as Jupiter moves to the up behind the moon.<\/p>\n

This is, again, motivation to see if I can get this damn telescope and tracking motor working properly. I make the attempt every once in a great while, but usually run up against one problem or another. The first issue is, I cannot see Polaris from Walkabout Estates, so even trying to align the scope properly means going someplace else, since the axis of rotation needs to be aligned to celestial North. On the last attempt, after confirming that the motor was indeed turning, I tried fudging it, getting as close as I could just for tests, but the sky clouded up even before I got the telescope mounted to the tripod. It’s been like this far too often, and this isn’t even accounting for the fact that the scope eyepiece mount stands out a DSLR camera too far to achieve focus, and I’d have to use something else to capture the images – those tests were also<\/em> laden with problems.<\/p>\n

“So you’re saying you’re not up to the challenge – is that it?” you reply, seemingly-innocently, and now it’ll depend on my mood as to whether I attempt to prove you wrong or refuse to be baited by your snark. If all else fails, I can still use the long lens, which is just-barely capable of resolving the Galilean moons<\/a>, but it would be much better with the scope. We’ll see.<\/p>\n","protected":false},"excerpt":{"rendered":"

Coming up on October 6th at roughly 08:15 UTC (which translates to 4:15 AM Eastern Daylight Time,) the crescent moon will occult Jupiter – for once, a nice target for an occultation, since it’s a planet and, at decent magnification, has both a shape and detail. Note that this is for North America and may […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[14,3],"tags":[8336,2361,5036,1599,1600,7148],"class_list":["post-42721","post","type-post","status-publish","format-standard","hentry","category-astronomy","category-photo","tag-crescent","tag-earthshine","tag-galilean-moons","tag-jupiter","tag-moon","tag-occultation"],"_links":{"self":[{"href":"https:\/\/wading-in.net\/walkabout\/wp-json\/wp\/v2\/posts\/42721","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wading-in.net\/walkabout\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wading-in.net\/walkabout\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wading-in.net\/walkabout\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/wading-in.net\/walkabout\/wp-json\/wp\/v2\/comments?post=42721"}],"version-history":[{"count":2,"href":"https:\/\/wading-in.net\/walkabout\/wp-json\/wp\/v2\/posts\/42721\/revisions"}],"predecessor-version":[{"id":42724,"href":"https:\/\/wading-in.net\/walkabout\/wp-json\/wp\/v2\/posts\/42721\/revisions\/42724"}],"wp:attachment":[{"href":"https:\/\/wading-in.net\/walkabout\/wp-json\/wp\/v2\/media?parent=42721"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wading-in.net\/walkabout\/wp-json\/wp\/v2\/categories?post=42721"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wading-in.net\/walkabout\/wp-json\/wp\/v2\/tags?post=42721"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}