Associate Professor of Earth, Environmental, and Planetary Science at WashU • NASA Planetary Data System Geosciences Node Director • Explorers Club EC50 • eeps.washu.edu/people/paul-byrne • he/himhttps://bsky.app/profile/theplanetaryguy.comhttps://bsky.app/profile/theplanetaryguy.com/post/3mvegwc6tjs24See that small bright object in the middle right of this image? That's the small icy moon Mimas. Floating in space against a backdrop of giant Saturn, the planet crossed by shadows from its rings.13 Sep 2026 01:27 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mvegwc6tjs24https://bsky.app/profile/theplanetaryguy.com/post/3mvenmabrxs2kLive Laugh Smash the Moon into Mercury for the lulz [contains quote post or other embedded content]13 Sep 2026 03:27 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mvenmabrxs2khttps://bsky.app/profile/theplanetaryguy.com/post/3mvegwc6tjs24See that small bright object in the middle right of this image? That's the small icy moon Mimas. Floating in space against a backdrop of giant Saturn, the planet crossed by shadows from its rings.13 Sep 2026 01:27 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mvegwc6tjs24https://bsky.app/profile/theplanetaryguy.com/post/3mvc2h3sz6c22I have a new paper out! Over the weekend I'll do a thread on what the Solar System can tell us about rocky exoplanets— but for now, enjoy this to-scale set of cross sections I made of the rocky worlds in *this* system! (They're all different, but still all variations on a theme...)12 Sep 2026 02:38 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mvc2h3sz6c22https://bsky.app/profile/theplanetaryguy.com/post/3mvc2h3sz6c22I have a new paper out! Over the weekend I'll do a thread on what the Solar System can tell us about rocky exoplanets— but for now, enjoy this to-scale set of cross sections I made of the rocky worlds in *this* system! (They're all different, but still all variations on a theme...)12 Sep 2026 02:38 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mvc2h3sz6c22https://bsky.app/profile/theplanetaryguy.com/post/3mv3yve4bbc2nThis is what our home looks like from 6 billion kilometres away.09 Sep 2026 16:55 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mv3yve4bbc2nhttps://bsky.app/profile/theplanetaryguy.com/post/3mv3yve4bbc2nThis is what our home looks like from 6 billion kilometres away.09 Sep 2026 16:55 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mv3yve4bbc2nhttps://bsky.app/profile/theplanetaryguy.com/post/3mv2qgamx722mIn honour of the day that's in it—the 60th anniversary of Star Trek.09 Sep 2026 04:50 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mv2qgamx722mhttps://bsky.app/profile/theplanetaryguy.com/post/3mv3pfptkes2zIn the long list of stupid ideas, this one's gotta be near the top. [contains quote post or other embedded content]09 Sep 2026 14:05 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mv3pfptkes2zhttps://bsky.app/profile/theplanetaryguy.com/post/3mv2qgamx722mIn honour of the day that's in it—the 60th anniversary of Star Trek.09 Sep 2026 04:50 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mv2qgamx722mhttps://bsky.app/profile/theplanetaryguy.com/post/3mv2bj5bxgk2xAstrophotographer Adam (AJ) Smadi caught this image a few hours ago from Washington state. A thin crescent Moon, sunlight illuminating the rugged lunar surface. And 2,400 times farther away—and on the other side of the Sun—mighty Jupiter, and its moons Io (left) and Ganymede (right).09 Sep 2026 00:24 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mv2bj5bxgk2xhttps://bsky.app/profile/theplanetaryguy.com/post/3muwrqz6j7k26Weird rock on Mars. Photographed yesterday.07 Sep 2026 15:04 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3muwrqz6j7k26https://bsky.app/profile/theplanetaryguy.com/post/3muuxxnftbk2mI was invited to write up a short blogpost for the Planetary Geomorphology Image of the Month based on our recent JGR Planets paper! We make the case that some of the highlands on Venus have borders that form in the same way mountain belts on Earth do: planetarygeomorphology.wordpress.com06 Sep 2026 21:49 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3muuxxnftbk2mhttps://bsky.app/profile/theplanetaryguy.com/post/3muwrqz6j7k26Weird rock on Mars. Photographed yesterday.07 Sep 2026 15:04 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3muwrqz6j7k26https://bsky.app/profile/theplanetaryguy.com/post/3muve7ovzvs2hGround- and space-based telescopes have revealed something new at Saturn: a giant, ten-sided structure in the clouds near the planet's south pole. This decagon is almost stationary, extends deep below the cloud tops, and is similar (though not quite the same) as the famous north pole hexagon.07 Sep 2026 01:29 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3muve7ovzvs2hhttps://bsky.app/profile/theplanetaryguy.com/post/3muve7ovzvs2hGround- and space-based telescopes have revealed something new at Saturn: a giant, ten-sided structure in the clouds near the planet's south pole. This decagon is almost stationary, extends deep below the cloud tops, and is similar (though not quite the same) as the famous north pole hexagon.07 Sep 2026 01:29 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3muve7ovzvs2hhttps://bsky.app/profile/theplanetaryguy.com/post/3muuxxnftbk2mI was invited to write up a short blogpost for the Planetary Geomorphology Image of the Month based on our recent JGR Planets paper! We make the case that some of the highlands on Venus have borders that form in the same way mountain belts on Earth do: planetarygeomorphology.wordpress.com06 Sep 2026 21:49 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3muuxxnftbk2mhttps://bsky.app/profile/theplanetaryguy.com/post/3mus7h5kbis2pIt took the Apollo astronauts three days to get to the Moon. The New Horizons spacecraft did that distance in nine hours. And it still took nine-and-a-half years to reach Pluto. The Solar System is stupid big. [contains quote post or other embedded content]05 Sep 2026 19:25 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mus7h5kbis2phttps://bsky.app/profile/theplanetaryguy.com/post/3mupx4ygjvk26That small black circle is the planet Mercury, seen crossing the face of the Sun by NASA's Solar Dynamics Observatory on 9 May 2016.04 Sep 2026 21:51 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mupx4ygjvk26https://bsky.app/profile/theplanetaryguy.com/post/3mus7h5kbis2pIt took the Apollo astronauts three days to get to the Moon. The New Horizons spacecraft did that distance in nine hours. And it still took nine-and-a-half years to reach Pluto. The Solar System is stupid big. [contains quote post or other embedded content]05 Sep 2026 19:25 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mus7h5kbis2phttps://bsky.app/profile/theplanetaryguy.com/post/3mupx4ygjvk26That small black circle is the planet Mercury, seen crossing the face of the Sun by NASA's Solar Dynamics Observatory on 9 May 2016.04 Sep 2026 21:51 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mupx4ygjvk26https://bsky.app/profile/theplanetaryguy.com/post/3munxmuejl22tOne of the finest photographs of our homeworld ever taken. The nightside of Earth, by the Artemis II Crew on the second day of the mission. Credit: NASA/Artemis II Crew04 Sep 2026 02:55 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3munxmuejl22thttps://bsky.app/profile/theplanetaryguy.com/post/3munxmuejl22tOne of the finest photographs of our homeworld ever taken. The nightside of Earth, by the Artemis II Crew on the second day of the mission. Credit: NASA/Artemis II Crew04 Sep 2026 02:55 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3munxmuejl22thttps://bsky.app/profile/theplanetaryguy.com/post/3mulbv4apck2kI saw that first pic and had to improve/ruin it [contains quote post or other embedded content]03 Sep 2026 01:20 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mulbv4apck2khttps://bsky.app/profile/theplanetaryguy.com/post/3mumpfw5ayc2bAfter almost eight years, 9 billion km, 9 planetary flybys, and 22 swings around the Sun, the two BepiColombo orbiters have successfully separated from their delivery vehicle. Acquisition of a successful separation confirmed!03 Sep 2026 14:55 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mumpfw5ayc2bhttps://bsky.app/profile/theplanetaryguy.com/post/3mulbv4apck2kI saw that first pic and had to improve/ruin it [contains quote post or other embedded content]03 Sep 2026 01:20 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mulbv4apck2khttps://bsky.app/profile/theplanetaryguy.com/post/3mukbrtj3pk2hApollo 11 photo As11-44-6642. Taken by Apollo 11 Command Module pilot Michael Collins, this image captures every living human alive at the time in a single frame—except for Collins himself.02 Sep 2026 15:46 +0000at://did:plc:wwbktud2d34ont3frkv73pjo/app.bsky.feed.post/3mukbrtj3pk2h