Saturn: Cassini may have photographed the birth of a moon. Photo by NASA/JPL/Space Science Institute Just when I think Saturn can’t surprise me any more: The Cassini spacecraft may have taken the birth pictures of a new moon! It may have also spotted its demise. Or maybe part of its demise. Also, it may be twins. Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death from the Skies! Follow him on Twitter. Follow The potential moon (nicknamed Peggy) is tiny, probably only about a kilometer (0.6 miles) across—really a moonlet—and is invisible in the Cassini pictures.
It was discovered by accident in an image taken on April 15, 2013—one year ago today. That’s clearly not a discrete object; it’s about 10 kilometers (6 miles) wide and 1,200 kilometers (740 miles) long, but this is what you would expect if a small object were located near the edge of the ring—and why astronomers think there's most likely a moonlet there. But then things get weirder. And we’re still not done. Science!
If Earth Had a Ring Like Saturn. Huge science error! Those are Saturn's rings. All the little gaps and ridges in the rings are due to the gravitational interactions of ring particles with Saturn's many moons. Since Earth has just the one moon, gaps in our rings would all be due to orbital resonances with that moon, creating a much more regular appearance. When that animation was going around the internet, I took a stab at figuring out exactly what the Earth's rings would look like, given reasonable assumptions for Roche limit, atmospheric drag effects, and lunar resonances.
SExpand (full writeup here) There are some interesting implications to having rings around a planet with primitive cultures, too. You are absolutely right about the gaps. Oh, yeah - they are tremendous images, and they definitely got my brain going! You can fix up the gaps for your next try! In Saturn's Rings - Official Teaser. Checking in on Saturn - The Big Picture. While we humans carry on with our daily lives down here on Earth, perhaps stuck in traffic or reading blogs, or just enjoying a Springtime stroll, a school-bus-sized spacecraft called Cassini continues to gather data and images for us - 1.4 billion kilometers (870 million miles) away.
Over the past months, NASA's Cassini spacecraft has made several close flybys of Saturn's moons, caught the Sun's reflection glinting off a lake on Titan, and has brought us even more tantalizing images of ongoing cryovolcanism on Enceladus. Collected here are a handful of recent images from the Saturnian system. (30 photos total) In orbit around Saturn, NASA's Cassini spacecraft captured this image of Saturn's moon Tethys with its prominent Odysseus Crater slipping behind Saturn's largest moon Titan.
Tethys (1,062 km, or 660 mi across) is more than twice as far from Cassini than Titan (5,150 km, or 3,200 mi across). Say “cheese” and give Saturn a wave on Friday July 19. Cassini photo mosaic of Saturn, backlit by the sun, back in September 2006. Earth is between tick marks at left. Click to supersize. Credit: NASA/ JPL-Caltech I’m a sucker for corny cosmic ideas. On Friday afternoon July 19, cameras on the Cassini spacecraft will take a series of photos of our home planet from nearly one billion miles away. NASA suggest we all wave. The probe, which has been circling Saturn since 2004, will take a series of photos of our home planet from nearly one billion miles away over a 15-minute span beginning at 4:27 p.m.
This simulated view from NASA’s Cassini spacecraft shows the expected positions of Saturn and Earth on July 19, 2013, around the time Cassini will take Earth’s picture. Seen from so far away Earth will be no more than 1.5 pixels wide, but squished into that dot will be all of us and every other living thing. Since the U.S. and Canada will be in sunlight when the photo’s taken, you’ll have to picture Saturn in your mind’s eye.