Captioned Photo: Messier 66 Close Up
Image Credit: NASA, ESA, Hubble; Processing & Copyright: Leo Shatz

Explanation: Big, beautiful spiral galaxy Messier 66 lies 35 million light-years away. It is similar in size to the Milky Way. This reprocessed Hubble Space Telescope close-up view spans a region about 30,000 light-years wide around the galactic core. It shows the galaxy’s disk dramatically inclined to our line-of-sight. Surrounding its bright core, the likely home of a supermassive black hole, obscuring dust lanes and young, blue star clusters sweep along spiral arms dotted with the tell-tale glow of pinksh star forming regions.

 

Moons

Jupiter is king of the planets. It’s huge, it’s bright in our night skies, and even four of its comparatively tiny moons are bright enough to see with the most basic of telescopes. We’ve sent nine probes either into orbit or on a close flyby of the planet. And yet, as recently as this past year, we discovered twelve new moons around Jupiter, bringing the total to 79.

Most of the 79 are irregular moons, and these make up the vast majority of Jupiter’s satellites. These tend more toward potato shapes, and their orbits are often eccentric, tilted, or even retrograde, meaning they fly backwards to Jupiter’s spin. Most are probably captured asteroids or the results of long-ago collisions of larger bodies — perhaps past moons of Jupiter. They’re tiny and tend to orbit farther out from Jupiter than the regular moons. This makes them much harder to spot.

NewJupiterMoonOrbits

One of Jupiter’s newest moons orbits prograde (normally), but since it’s among the retrograde (backwards) moon group, it’s probably marked for a deadly collision before too long.

 

Moons Cause Tilt…

Scientists have just shown that the influence of Saturn’s satellites can explain the tilt of the rotation axis of the gas giant. Their work also predicts that the tilt will increase even further over the next few billion years.

Recent observations have shown that Titan and the other moons are gradually moving away from Saturn much faster than astronomers had previously estimated. By incorporating this increased migration rate into their calculations, the researchers concluded that this process affects the inclination of Saturn’s rotation axis: as its satellites move further away, the planet tilts more and more.

The decisive event that tilted Saturn is thought to have occurred relatively recently. For over three billion years after its formation, Saturn’s rotation axis remained only slightly tilted. It was only roughly a billion years ago that the gradual motion of its satellites triggered a resonance phenomenon that continues today: Saturn’s axis interacted with the path of the planet Neptune and gradually tilted until it reached the inclination of 27° observed today.

Melaine Saillenfest, Giacomo Lari, Gwenaël Boué. The large obliquity of Saturn explained by the fast migration of Titan. Nature Astronomy, 2021; DOI: 10.1038/s41550-020-01284-x

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13 COMMENTS

  1. A lot of mystery out there, and am still amazed at Hubble photos. Stunning.

    From “Contact” (based on Sagan’s book)…” The universe is a pretty big place. It’s bigger than anything anyone has ever dreamed of before. So if it’s just us… seems like an awful waste of space.”

    God will reveal the mystery when we shift from here to there.

    • Thank you to all who were concerned with the blog going down earlier today. DNS attack, thwarted, and we’re back in business.

      • Turds. Guess to them free speech is only what they say and therefore entitled to squash anyone who disagrees.

        Nice thwart-age….glad yer up an’ runnin’…we all need our morning Mirage. Best with coffee.

        • Add a sinker to the Life Blood of the Navy. Pogey bait may not extend your life, but it is a naval tradition.

      • The email provider I subscribe to is currently being blocked by Microsoft hosts.
        Any email I try to send to people using them get sent back with an UNDELIVERABLE message.
        Wonder how extensive this round of blockage will be.

        • I’m trying to take all this a day at a time, Frank. Be sure to read Virtual Mirage on Saturday. No spoilers.

  4. I find it interesting to ponder the effects of scientific advancements on mankind’s belief systems over several millennia.
    For instance Hittites, Sumerians, Persians, Hebrews, Egyptians, even Greeks and Romans got along just fine with the world as they knew it.
    But by the 16th century scientists (heretics) encountered increasing obstruction, religious and secular.

  5. Just a Fun Fact. The statement about M66, “This reprocessed Hubble Space Telescope close-up view spans a region about 30,000 light-years wide around the galactic core. It shows the galaxy’s disk dramatically inclined to our line-of-sight” means that no view of the galaxy shows it at one moment in time. As you look across the galaxy you’re looking at things positioned 30,000 years apart. That’s about 7 times all of recorded human history.

    The amount of time distortion varies, but virtually every galaxy we can see is distorted in time.

    • Light years is a measure of distance, not time. Your post made me stop and think, my friend. Thank you for that.

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