Why Jupiter Has No Rings

The title is false, Jupiter does have rings, but they are so thin, they are very hard to see, even in the best of conditions.

But why does Jupiter not have big, beautiful rings like Saturn? A recent article I read said Jupiter's moons are to blame. If it didn't have all those giant moons, it would have rings much bigger and more spectacular than Saturn's.

A new study says that giant moons destroy rings before they have a chance to form. And the Galilean moons of Jupiter, one of which is the largest moon in the solar system, seem to be good at it. Therefore, it is unlikely Jupiter ever had large rings at any point.

Massive planets form massive moons, which prevent them from having substantial rings.

Well, I thought the article had more to it than that, but that seems to be the sum total of it.

In a 'related' video, which I didn't watch for lack of time, the headline said Jupiter may have 'eaten' some sibling planets while it was growing. That sound interesting, so I'll keep my eyes open for more on that, but I suspect it will be as thin as Jupiter's rings.

 

https://www.msn.com/en-us/news/technology/scientists-solve-the-reason-why-jupiter-has-no-rings/ar-AAZRF0k?ocid=mailsignout&li=BBnbfcL

Weird Planets 10

Good morning! Congratulations on completing the first 9 installments of your tour. We don’t have as many worlds to visit as yesterday, so there will be ample time to relax. If you want a pillow or beverage, press the blue button on your arm rest, and either CXQ-9 or CXQ-10 will tend to you. Now, if everybody is comfortable, we’ll get started.

Excuse me. I’m sorry to disturb you, but we are entering the system of today’s first planet. If you turn your attention to your viewers, currently on their maximum magnification, you’ll see a small deep-pink blob. This is GJ-504b, the Pink Planet, 57.3 light years from Earth. The dark pink glow of GJ-504b is caused by the remaining heat of its formation. It’s about the same size as Jupiter, but it’s further from its sun than Neptune is from ours. Scientists didn’t think such a large planet could form at that distance because there wouldn’t be enough dust and debris. Your viewers will adjust their magnification as we approach and swing past, so you can get a good look.

Your attention, please. We are now 434 light-years from Earth, approaching planet J1407B, which is described as a ‘Super-Saturn’. It has a mass of 40 Jupiters and 37 rings surround it, spanning 120 million kilometres. That’s about 200 times the size of Saturn’s rings. Some scientists think these rings may be in the process of forming moons, which has them quite excited, since they’ve never seen that happen outside of our solar system. Actually, even within our system, we haven’t seen it happen.

CXQ-9 and -10 will serve brunch as we move on, complete with champagne! Enjoy!

Good afternoon! Your viewers are currently showing KOI-314c, the lightest planet to have both its mass and physical size measured. Rather surprisingly, it has the same mass as Earth, but is 60% larger in diameter. If you weigh 100 pounds on Earth, you will still weigh 100 pounds on KOI-314c. However, the larger diameter seems to indicate a very thick atmosphere. If you look slightly to the left of the planet’s image, you’ll see the red dwarf star that it orbits. This system is about 200 light-years from Earth. Yes, we are already headed back to the tour station.

This is our final viewing for today. This is Epsilon Eridani b, which orbits an orange Sun-like star only 10.5 light years from Earth. Before long, Earth telescopes may be able to photograph it directly. Unfortunately, it is too far from its star to have liquid water or life as we know it. However, I’m going I’ll make a couple low orbits around it and set your viewers on maximum, and you can all try to spot life as we don’t know it!

Ladies and Gentlemen, we have returned to the tour station. I hope you have enjoyed your day with Star Tours. Er, I mean, Planet Tours.

http://www.popularmechanics.com/space/deep-space/g1265/space-oddities-8-of-the-strangest-exoplanets/

http://www.express.co.uk/news/science/643662/The-10-weirdest-planets-to-have-been-discovered-so-far

www.space.com/159-strangest-alien-planets.html

Rings

I’ve talked before about our solar system as if it were a family, with the sun as the parent, and the planets as the children. The moons, asteroids and other bits would be the grandchildren, I suppose.

I am quite fascinated with our solar system. Until scientists find facts about other solar systems, this is the only one I’ve got to study; these are the only planets I can use as a springboard when my imagination wants to design one for a story. So I keep looking for new things about them that I didn’t know before. Luckily, NASA and scientists keep looking at them, too.

Today’s subject is Saturn and its rings.

You’d think the solar system was a big family, with 9 8 planets and several dwarf planets. But for Saturn, 8 or 9 was not enough. Saturn has 62 moons that have names, and another 9 that have not yet been named. Wow! Can you imagine 71 kids? I’d have lots of trouble remembering half their names, not just 9 of them. I had a couple batches of cousins who had 8 siblings in each family. Gram gave up trying to remember our names; all the girls became ‘Pigtails’ and the boys were ‘Junior’.

I didn’t realize just how many moons Saturn has. One day I will have to start looking more closely at them, but today, I’m looking at the rings.

There are 7 rings. They don’t exactly have names, but each is designated by a letter. I suspect the letters were assigned as the individual rings were discovered, because otherwise, there doesn’t appear to be any rhyme or reason for the assignments.

If you start at Saturn and move away from the planet, you arrive at Ring D, then Ring C, Ring B and Ring A. Continue outward, and you will find Ring F, Ring G and Ring E. Between each pair of rings is a gap, a space that is not absolutely empty, but is relatively empty compared to the rings. (I haven’t figured out if any of the gaps is home to a moon, but I do know that some of the moons are somewhere in the ‘rings’. Some day, I have to figure that out.) Each ring and gap is its own width, meaning the distance between the side closest to Saturn and the side furthest from Saturn.

But they are also thin, meaning the distance from the ‘top’ of the ring to the ‘bottom’. Thickness for all the rings is less than 1 km.

If there is one thing Saturn’s rings are, it’s not consistent. The various rings are made up of water ice particles (with a trace of rock for flavoring), but those particles range from the size of a grain of sugar to the size of a house.

The rings are a very busy place. With 71 moons of various sizes orbiting around this big ol’ gas giant, the gravity and magnetic fields are forever fluctuating. The latest probe documented ‘lines’ in some rings, which are called spokes. The spokes come and go, and they aren’t sure what causes them, but they suspect they are a temporary ‘pile-up’ (traffic jam) of particles caused by the gravity or magnetic fields. Or maybe by electricity leaking from storms in Saturn’s upper atmosphere.

And spokes are not the only oddity in the rings. Ring F seems to be ‘braided’. Who taught those particles how to do that?

But don’t worry about Saturn’s rings. Some of the moons (bigger siblings) act as shepherds for the rings, using their gravity/magnetic fields to keep the ring particles where they belong. More or less.

I’ve just barely touched on Saturn, but that’s all for today. After all, it is a gas giant, with a huge family; too big a subject for me to explore the entire thing in one sitting.

  

http://nineplanets.org/saturn.html

Dione

I thought we’d talk about Dione today. That was before I found out there were 4 ‘Dione’s’ in Greek mythology and one in the Phoenician mythology of Sanchuniathon. Rather than try to sort through all those, I changed my mind and decided to discuss Dione, a moon of Saturn. (What or who is Sanchuniathon? I may have to come back to that one sometime.)

This moon was discovered by Giovanni Domenico Cassini in 1684. It is also sometimes called Saturn IV.

Dione’s orbit around Saturn is an ellipse, and at its closest approach, it is slightly closer to Saturn’s center than our own moon is to the Earth’s center. Because Saturn is a lot bigger than Earth, Dione races around it, taking 2.74 days to complete an orbit, as well as a Dione ‘day’. It never turns its face away from Saturn. It’s interesting that every time Dione completes one orbit, Enceladus (another Saturn moon) completes two. Each time they pass each other, the gravimetric tugging generates internal heat in both moons.

Also interesting is that Dione is one of a set of triplets. Two other moons of Saturn, Helene and Polydeuces, share the same orbit as Dione. They run around Saturn in single file, one 60° ahead of Dione, and the other 60° behind.

Who knew this kind of stuff could actually happen ‘naturally’? May I should have stuck with mythology after all.

It is believed that Dione is about 2/3 water in various forms, and the remainder is a dense core of silicate rock. The top of the ‘water’ is an ice crust, probably as thick as 99 kilometers ( 62 miles). The temperature at Dione’s surface is about -121°F, which would make the ice so hard, it would act like rock. Between the rock core and the ice crust is about 65 km ( 41 miles) of liquid ocean. The crust does have various features, such as chasms, ridges, long narrow depressions, craters and crater chains.

Dione is pretty well covered in craters, as large as 100 km (62 miles) across. However, most of the craters are on the opposite side as scientists expect them to be. The theory is that on something the size and mass of Dione, anything big enough to make a 35 km (22 mile) crater would be able to spin the moon about. There are enough large craters to indicate Dione did a lot of spinning in the past. So maybe she keeps her back to Saturn, trying to see the next spin-inducing attacker before it hits?

Oh, and let’s not forget the ice cliffs (formerly known as ‘wispy terrain’ when it was discovered by the Voyager space probe). At the time, they were called ‘wispy’ because whatever they were, they didn’t hide the countryside in their vicinity. But more recent photos by Cassini show that these ‘wispy’ lines were, in fact, ice cliffs, fractures created by chasms. We now know that some of them are several hundreds of meters tall.

In 2010, the Cassini probe detected oxygen ions around Dione, but there were so few of them, scientists prefer to call it an exosphere rather than a tenuous atmosphere.

en.wikipedia.org/wiki/Dione_(moon)

https://solarsystem.nasa.gov/planets/dione

Twins

I consider Pluto and Charon twins. They run around the sun, constantly together, and pretty much ignoring all their other siblings. Pluto was discovered in 1930, and was considered a planet until fairly recently, when it was demoted to dwarf planet.

Charon wasn’t discovered until 1978, and is usually considered Pluto’s closest and largest moon. However, there are scientists who (like me) think Pluto and Charon should be classified as a binary dwarf planet unit. For one thing, Charon’s diameter is slightly more than half of Pluto’s, which is very large for a moon. The relative sizes of a moon to its planet rarely approach that, from what we’ve been able to observe so far. Charon’s size is so large, compared to Pluto’s, that - strictly speaking - it doesn’t actually revolve around Pluto. Both of these twins revolve around a point somewhere between them. Kind of like 2 kids on a playground, holding each other’s hands and spinning around, laughing as they get dizzy and the world around them starts to look silly. And like those 2 kids, they don’t allow the 4 remaining ‘moons’ to join them. The tiny moons revolve around the pair, wishing they were part of the game.

Pluto’s diameter is 2,372 km[1,474 miles], making it the largest dwarf planet we know of. My quick research didn’t find Charon’s exact diameter, but it’s slightly more than 1,186 km[737 miles], which certainly makes it larger than Ceres (950 km)[590 miles].

While NASA’s probe thoroughly studied Pluto, it didn’t neglect Charon. Since it was there, why waste the opportunity? And aside from size, they do rather resemble each other.

Both Pluto and Charon are believed to have a rocky core surrounded by water ice, with other ices covering that. And at the temperatures experienced that far out, water ice is as hard as stone. I find that a little hard to fathom, but not impossible to accept.

Pluto and Charon are tidally locked, meaning each keeps the same side facing the other at all times. Rather like the 2 kids mentioned earlier. But they must have gotten so dizzy they fell over, because they travel around the sun on their sides - still revolving around each other. Maybe the twins got the idea of laying down from Uranus.

And like Uranus and Venus, Pluto rotates backwards, so that sun rises in the west and sets in the east. I found no mention of Charon doing that.

Both of the twins have some interesting features, like Pluto’s ‘heart’, which is a huge glacier made of Nitrogen ice, and Charon’s huge chasm that crosses its entire face. The ‘southern’ half of Charon is smoother and has less craters than the ‘northern’ half. The current thought is that when Charon’s internal water froze (and therefore increased in volume), the pressure forced some partially frozen water out as a type of lava. Remember Ceres’ cryovolcano?

For at least part of its year, Pluto has an atmosphere, or maybe it should be called ‘layers of haze’. And some of it is escaping into space, but not as much as scientists expected, and mostly methane, not the nitrogen they expected would be leaving. I thought I had heard that Charon also had some haze, possibly borrowed from Pluto, but I couldn’t find anything like that during my research, so I may have mis-heard or misunderstood what was said.

And now, I’m going to give a self-satisfied raspberry to those who decided Pluto was ‘just’ a dwarf planet. It (and Charon) were full of surprises and brain-twisting facts for the entire New Horizons team that studied the incoming data. Way to go, Twins!

Water, Water Everywhere

Earth has a lot of water; it covers roughly 75% of the planet’s surface, and it gets pretty deep - not quite 7 miles deep at one point. And for a long time, it seemed maybe Earth was the only planet in this solar system that had water.

If we sent people to explore or colonize any of the other planets, we would have to send water with them. The more people we sent, the more water they would need. Did Earth have enough? Would we completely drain the oceans?

Thankfully, we’ve learned better than that by now, since we are - tentatively - thinking about how best to colonize other planets. A brief recap:

1989 - Voyager studied Neptune’s magnetic field, leading to the conclusion that it has a subsurface ocean of water that is 4000°F (Hot!) and is under tremendous pressure.

1998 - Recent discoveries convince scientists that Callisto (a moon of Jupiter) might have a subsurface ocean.

2006 - Neptune has a large amount of water mixed in with its hydrogen/helium atmosphere. This is true also for Uranus, and since its density is only slightly higher than water, there is speculation that most of Uranus is water, in all its forms, with only a tiny rocky core.

2009 - Traces of water were found on the moon, then a ‘significant’ amount of water. Plans are being made for mining it, should we ever decide to colonize or set up a station there.

2010 - Water ice was found on two asteroids. Some surmised that there might be lots of water ice in the asteroid belt.

2011 - It was concluded that dark streaks on Martian slopes were made as salty water (ice) melts and slides down the slope. Water ice is also trapped in Mars’ polar caps, which can reach halfway to its equator during the winter. And a huge slab of underground water ice has been found in its northern hemisphere.

2014 - Ceres, the dwarf planet in the asteroid belt, was found to be spewing water vapor into space. It was speculated that Ceres might have more water than Earth does.

2014 - Gravity measurements suggest that a huge ocean sloshes around under the icy surface of Saturn’s moon Enceladus, which also spews water vapor from vents in its south pole. Titan, another Saturn moon, has an under-crust ocean saltier than Earth’s Dead Sea.

2014 - Scientists re-examined data from 1989, and now wonder if there is a subsurface ocean on Triton, Neptune’s largest moon - even if it does have the coldest surface in the solar system.

2015 - Using the Hubble Space Telescope, scientists found that Jupiter’s moon Ganymede has a huge salty ocean buried under a thick crust of ice. Laboratory experiments lead to the conclusion that there’s a subsurface salty ocean on Europa, another of Jupiter’s moons.

2015 - Water ice sheets were discovered on Pluto.

You get the idea - there’s plenty of water out there. It’s so fascinating a subject because life AS WE KNOW IT needs water. So when we find water - especially liquid water - in places you would think would be too cold, the next question is, Is there life there?

Let’s go find out.