[HN Gopher] Saturn's rings are far younger than once thought
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Saturn's rings are far younger than once thought
Author : geox
Score : 60 points
Date : 2023-05-13 16:16 UTC (6 hours ago)
(HTM) web link (www.colorado.edu)
(TXT) w3m dump (www.colorado.edu)
| jmyeet wrote:
| Here's another factor: over 4.5 billion years we really don't
| have a good idea of what close neighbours the Solar System has
| had. Stars are orbiting the Milky Way and I seem to remember
| reading not that long ago (hundreds of thousands of years) our
| closest neighbour wasn't Proxima Centauri but some other star
| that is now further away.
|
| What other neighbours have we had? How bright have they been? How
| close have they been? Could they have been bright enough to melt
| ice? If so, would this impact the dust layer? Could they be
| massive enough to disrupt the "dusting"?
| trilbyglens wrote:
| None close enough to have any effects like that. If there had
| been any close enough to have a gravitational influence the
| planets orbits would be either super scrambled up, or they
| would have gotten yeeted off into interstellar space.
|
| "Close" in terms of stars is still super duper far apart.
| djmips wrote:
| > The planet's rings, in other words, are new phenomena, arising
| (and potentially even disappearing) in what amounts to a blink of
| an eye in cosmic terms.
|
| If the universe is ~14 billion years, 400 million is only 1/35th.
| A person blinks thousands of times a day and maybe 400 million
| times in their lifetime. I don't really know but is 400 million
| years really a blink of an eye in cosmic terms?
| Sharlin wrote:
| 400 My is almost 10% of the age of the Solar System. Definitely
| not a blink of an eye.
| dexwiz wrote:
| Should read "in what amounts to a quick commute in cosmic
| terms".
| ant6n wrote:
| More like a year in the life of the cosmos.
| dexwiz wrote:
| Maybe people spend about a year of their lives commuting.
| If you commute an hour a day, every weekday, for 40 years,
| that's 10400 hours, compared to the 8760 hours in a year.
| JoeyJoJoJr wrote:
| The total lifetime of the universe will be hundreds of
| trillions of years, which is perhaps a better scale to compare
| against.
| [deleted]
| jmac01 wrote:
| A human blink takes about 0.1s. And spends roughly 75 years
| alive.
|
| Blink/s/min/hr/day/years= 0.1/60/60/24/365/75 = ~4*e-11 ratio
| of blinks to years alive
|
| Age of universe is 14Byears
|
| 14,000,000,000 * 4*e-11 = 0.59 years.
|
| A cosmic blink is about 7months
| excalibur wrote:
| If we blow ourselves up, will all of the junk we left in orbit
| around the earth eventually form rings of garbage?
| rglover wrote:
| The Wall-E Hypothesis
| justrealist wrote:
| No, the vast majority is in LEO and will drop in a few decades.
| DoreenMichele wrote:
| _In 1610, Italian astronomer Galileo Galilei first observed the
| features through a telescope, although he didn't know what they
| were. (Galileo's original drawings make the rings look a bit like
| the handles on a water jug)._
|
| They are made mostly of ice, which I didn't know, and may be
| raining down onto the planet. They could disappear in 100 million
| years.
| robotresearcher wrote:
| Surely they must be raining down on the planet unless there's
| an energy input from somewhere.
| maxbond wrote:
| Why do you say that? The moon isn't raining down on us, it's
| actually slowly drifting away. Is there a reason they
| couldn't be in a stable orbit?
| saiya-jin wrote:
| which makes me think, what a spectacle it must have been
| 200-300 million years ago
| zamadatix wrote:
| I had always heard they were thought to be much younger than this
| new number. https://astronomy.com/news/2019/01/saturns-rings-are-
| surpris...
| Sharlin wrote:
| Yeah, 400 My is definitely on the older side of these "young
| rings" estimates.
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