Astronomy

[YesNo]

It seems that the reason they think the rings rotate in the opposite direction is because they are still there for us to observe. Otherwise they would have been thrown off during the early period of that system's existence.

[Dreamwoven]

It seems that the reason they think the rings rotate in the opposite direction is because they are still there for us to observe. Otherwise they would have been thrown off during the early period of that system's existence.

I don't follow you, YesNo. What would have been thrown off, the rings?

[YesNo]

I think that is what Rieder was saying when he was quoted. I may have misunderstood him. The ring system would be unstable if it moved in the same direction as the planet. If it is a ring, then it would have to go in the opposite direction we expect. Or perhaps it is not a ring but something else.

[desiresjab]

The ring moving in an opposite direction to the planet is intriguing. I never even thought of that before. What do the rings of Saturn do?

[Dreamwoven]

I think it is very rare that rings move in an opposite direction, the result of a catastrophic event:

How such a ring system could have come about is a mystery, as retrograde ring systems are quite uncommon. But Rieder and Kenworth have stated that they think it might be the result of a catastrophic event – such as a massive collision – that caused the rings (or the planet) to change the direction of their rotation. (http://www.universetoday.com/131403/...ngs-intrigues/).

That's all we know at this point in time.

[Dreamwoven]

New Horizons is on its way deeper into the Kuiper Belt. It is heading for this odd-shaped object. Visit this space.com article for more details: http://www.space.com/34429-new-horiz...red-color.html

[Dreamwoven]

The object is very peculiar, as can be seen from the picture.

[Dreamwoven]

http://www.universetoday.com/131597/...as-comet-came/

This is an interesting post, it plots the orbit of rosetta's comet, based on what we know of its movements while being tracked by the probe.

[YesNo]

The object is very peculiar, as can be seen from the picture.

We'll get to see how close the artist's rendering of the object is to the actual data coming back.

[Dreamwoven]

Yes, and this is how it was for New Horizons when it passed Pluto. All we knew is that it was a dot in the sky. We are still receiving data analyses from around the world, earthquakes, landslides, volcanic eruptions, its quite a remarkable catalogue. The same can happen again, with this much smaller object. it will indeed be exciting to see the results.

[Dreamwoven]

The moons of Mars - Deimos and Phobos - there is an explanation, worth reading: http://www.universetoday.com/14908/mars-moon-deimos1/

[Dreamwoven]

Moons are still being discovered around Uranus:

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 432 2016 October 23



POSSIBLE ADDITIONAL MOONS AROUND URANUS'S RINGS
University of Idaho

After re-examining data acquired by the Voyager 2 spacecraft,
astronomers have detected wavy patterns in two of Uranus's rings --
patterns that may be indicative of two undiscovered moons. Like the
other gas giants in the Solar System, Uranus has a ring system, though
it is not nearly as spectacular as the one around Saturn. And like
the other gas giants, Uranus has a lot of natural satellites -- 27 are
now known. New research suggests that that number might have to be
revised; data collected by Voyager 2 during its historic 1986 fly-by
hint at two undiscovered moons lurking near a pair of Uranus rings.
The suspected new moons reside in Alpha and Beta -- the 5th and 6th
rings. Voyager 2 found 10 moons when it visited the planet in 1986,
tripling the number of moons known to orbit the gas giant. The two
rings exhibit a series of wavy patterns consistent with the presence
of two tiny moons. The patterns may be wakes from small moonlets
orbiting outside those rings. Importantly, the observations are
consistent with how Uranus's other moons, such as Cordelia and
Ophelia, are exerting gravitational pressure on the dust, rocks, and
ice within the rings, herding the particles along a narrow formation.
If the now-postulated moons exist, they are quite dark and small,
measuring only 4 to 14 km across. That would make them smaller than
any other known moons orbiting the planet, which explains why Voyager
2 did not detect them directly. The researchers are now planning to
inspect Uranus with the Hubble telescope.

[YesNo]

Those possible, tiny moons around Uranus makes me wonder what criteria distinguishes a moon from one of the particles in a ring.

[Dreamwoven]

Perhaps the Hubble 'scope will be able to produce more info. But ultimately, rings and moons probably shade into one another?

[Dreamwoven]

Perhaps the Hubble 'scope will be able to produce more info. But ultimately, rings and moons probably shade into one another?