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<blockquote style="position: relative; padding-left: 55px;"><section><a href="https://mathstodon.xyz/users/johncarlosbaez/statuses/114476935533507844">John Carlos Baez (johncarlosbaez@mathstodon.xyz)'s status on Saturday, 10-May-2025 06:45:59 JST</a><a href="https://mathstodon.xyz/@johncarlosbaez" title="johncarlosbaez@mathstodon.xyz"><img src="https://gnusocial.jp/avatar/83718-48-20250418093131.webp" width="48" height="48" alt="John Carlos Baez" style="position: absolute; left: 0; top: 0;">John Carlos Baez</a><div><a href="https://mathstodon.xyz/@johncarlosbaez/114476903716555935" rel="in-reply-to">in reply to</a></div></section><article><p>This 2005 photo, taken by the Cassini probe, was the first time anyone actually saw Saturn's moon Daphnis!   It's only 8 kilometers across.</p><p>This gap in Saturn's A ring was first discovered by Voyager, and it was named the Keeler Gap.   It's 35 kilometers wide.   I guess this gap let people guess the existence of a moon, and later the ripples in the A ring let people guess where the moon must be!   I don't really know the history here. </p><p>(2/n)</p></article><footer><a rel="bookmark" href="https://gnusocial.jp/conversation/5030357#notice-9860601">In conversation</a><time datetime="2025-05-10T06:45:59+09:00" title="Saturday, 10-May-2025 06:45:59 JST">about a month ago</time> <span>from <span><a href="https://mathstodon.xyz/@johncarlosbaez/114476935533507844" rel="external" title="Sent from mathstodon.xyz via ActivityPub">mathstodon.xyz</a></span></span><a href="https://mathstodon.xyz/@johncarlosbaez/114476935533507844">permalink</a><h4>Attachments</h4><ol><li><label><a rel="external" href="https://gnusocial.jp/attachment/4603402">Daphnis is visible as a white speck between a more rippled ring to the left and a less rippled one to the right.   From https://photojournal.jpl.nasa.gov/catalog/PIA06237"Cassini's confirmation that a small moon orbits within the Keeler gap in Saturn's rings is made all the more exciting by this image, in which the disk of the 7 kilometer-wide body (4-miles) is resolved for the first time.The new body, provisionally named S/2005 S1, was first seen in a time-lapse sequence of images taken on May 1, 2005, as Cassini began its climb to higher elevations in orbit around Saturn (see PIA06238 for the movie). This view was acquired one day after the discovery sequence of images and has allowed scientists to measure the moon's size and brightness.This image was obtained with the Cassini spacecraft narrow-angle camera on May 2, 2005, at a distance of about 594,000 kilometers (369,000 miles) from Saturn. Cassini was about 525,000 kilometers (326,000 miles) above the ringplane when the image was taken. Resolution in the original image was 3 kilometers (2 miles) per pixel. The image has been magnified by a factor of two, and contrast has been enhanced, to aid visibility of the small moonlet."</a></label><br><a href="https://media.mathstodon.xyz/media_attachments/files/114/477/999/855/427/933/original/4353ace75b0f3f40.jpg" rel="external">https://media.mathstodon.xyz/media_attachments/files/114/477/999/855/427/933/original/4353ace75b0f3f40.jpg</a></li></ol></footer></blockquote>

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John Carlos Baez (johncarlosbaez@mathstodon.xyz)'s status on Saturday, 10-May-2025 06:45:59 JST John Carlos Baez
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This 2005 photo, taken by the Cassini probe, was the first time anyone actually saw Saturn's moon Daphnis! It's only 8 kilometers across.
This gap in Saturn's A ring was first discovered by Voyager, and it was named the Keeler Gap. It's 35 kilometers wide. I guess this gap let people guess the existence of a moon, and later the ripples in the A ring let people guess where the moon must be! I don't really know the history here.
(2/n)
In conversationabout a month ago from mathstodon.xyzpermalink
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1. Daphnis is visible as a white speck between a more rippled ring to the left and a less rippled one to the right. From https://photojournal.jpl.nasa.gov/catalog/PIA06237 "Cassini's confirmation that a small moon orbits within the Keeler gap in Saturn's rings is made all the more exciting by this image, in which the disk of the 7 kilometer-wide body (4-miles) is resolved for the first time. The new body, provisionally named S/2005 S1, was first seen in a time-lapse sequence of images taken on May 1, 2005, as Cassini began its climb to higher elevations in orbit around Saturn (see PIA06238 for the movie). This view was acquired one day after the discovery sequence of images and has allowed scientists to measure the moon's size and brightness. This image was obtained with the Cassini spacecraft narrow-angle camera on May 2, 2005, at a distance of about 594,000 kilometers (369,000 miles) from Saturn. Cassini was about 525,000 kilometers (326,000 miles) above the ringplane when the image was taken. Resolution in the original image was 3 kilometers (2 miles) per pixel. The image has been magnified by a factor of two, and contrast has been enhanced, to aid visibility of the small moonlet."
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