{"id":88477,"date":"2025-10-18T10:02:07","date_gmt":"2025-10-18T10:02:07","guid":{"rendered":"https:\/\/www.newsbeep.com\/ie\/88477\/"},"modified":"2025-10-18T10:02:07","modified_gmt":"2025-10-18T10:02:07","slug":"io-europa-and-their-shadows-cross-jupiter","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ie\/88477\/","title":{"rendered":"Io, Europa, and their shadows cross Jupiter"},"content":{"rendered":"

\t\t\tBack to Article List\t\t<\/p>\n

\n\t\t\t\tJupiter\u2019s two innermost Galilean moons cross in front of the planet, playing tag with their shadows this morning.\t\t\t<\/p>\n

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\n\t\t\t\t\t\tBy 6 A.M. CDT, both Io and Europa\u2019s shadows are visible on Jupiter\u2019s cloud tops, as the moons themselves prepare to transit. Callisto and Ganymede lie farther east (to the left in this view). Credit: Stellarium\/James Hastings-Trew\/NASA Cassini\t\t\t\t\t<\/p>\n

On October 17th, early morning observations of Jupiter will feature transits of Io’s and Europa’s shadows across its cloud tops, with specific timings varying by time zone.
\nA telescopic view of Jupiter on this date will reveal all four Galilean moons strung out to its east.
\nThe subsequent morning will present a conjunction of the waning crescent Moon (4% illuminated) and Venus (94% illuminated, gibbous phase) in the predawn sky within the constellation Virgo.
\nBelow this conjunction, the 3rd-magnitude double star Porrima (Gamma Virginis), with components approximately 4\u201d apart, will be observable through a telescope.<\/p>\n

Looking for a sky event this week? Check out our full\u00a0Sky This Week<\/a>\u00a0column.\u00a0<\/p>\n

October 17: Catch open cluster M34<\/a><\/p>\n

Jupiter stands high in the sky early this morning, ripe for viewing as two of its four Galilean moons chase their shadows across the cloud tops.\u00a0<\/p>\n

By 6 A.M. EDT, the gas giant stands nearly 60\u00b0 high in the southeast, below (and outshining) the two bright stars marking the heads of Gemini the Twins. Zoom in on the planet with a telescope to see all four Galilean moons strung out to the planet\u2019s east. Io is closest to the planet; next is Europa, then Callisto, with Ganymede farthest east.\u00a0<\/p>\n

Make sure you\u2019re ready about half an hour later, as Io\u2019s shadow is first to appear on the southeastern limb at 6:36 A.M. EDT. Europa\u2019s shadow appears six minutes later. Io reaches the limb and starts to transit at 6:52 A.M. CDT, as twilight is starting to brighten skies across the Midwest. The western U.S. will be able to watch as\u00a0Callisto\u2019s shadow appears at the southeastern limb at 6:07 A.M.\u00a0 PDT (note the time change). Twelve minutes later, Europa begins its transit at 6:19 A.M. PDT, with Io finally beginning to approach the southwestern limb.\u00a0<\/p>\n

Sunrise:\u00a07:14 A.M.
Sunset:\u00a06:15 P.M.
Moonrise:\u00a04:25 A.M.\u00a0
Moonset:\u00a04:58 P.M.
Moon Phase:\u00a0Waning crescent (5%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40\u00b0 N 90\u00b0 W. The Moon\u2019s illumination is given at 10 P.M. local time from the same location.<\/p>\n

Tomorrow morning, The Moon and Venus hang close together in the predawn sky, sharing the sky in the constellation Virgo. An hour before sunrise, look east to spot Venus, the brightest point of light, blazing at magnitude \u20133.9 nearly 7\u00b0 above the horizon and climbing. The delicate crescent Moon lies to its upper right, just 4\u00b0 to the planet\u2019s west.\u00a0<\/p>\n

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\t\tVenus and the Moon rise before the Sun this morning, visible in the constellation Virgo. The double star Porrima is also available for those with a clearer eastern horizon. Credit: Stellarium\/USGS\/Celestia\/Clementine<\/p>\n

Through a telescope, Venus appears 94 percent lit, its gibbous phase opposite the Moon\u2019s thin crescent phase, with only some 4 percent of our satellite lit this morning. Venus\u2019 disk stretches 11\u201d on the sky, making its phase readily visible in the eyepiece.\u00a0<\/p>\n

Below them will be the 3rd-magnitude star Porrima (Gamma Virginis), a famous double star with components about 4\u201d apart, easy to split in a telescope. They are nearly identical blue-white suns that shine at roughly the same magnitude.\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"Back to Article List Jupiter\u2019s two innermost Galilean moons cross in front of the planet, playing tag with…\n","protected":false},"author":2,"featured_media":88478,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[61,60,7882,82,44123],"class_list":["post-88477","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-ie","tag-ireland","tag-observing","tag-science","tag-sky-tonight"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/88477","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=88477"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/88477\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/88478"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=88477"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=88477"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=88477"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}