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Old 09-13-2019, 03:15 PM
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Looks like there may be another interstellar object passing through the Solar System.


From Phil Plait, this one is reportedly both much faster and much larger ("several kilometers" versus "about 100 meters") than 'Oumuamua from a couple of years back.

They must have found the results sent back by their scout cruiser to be interesting enough to warrant sending in a far larger Star Dreadnought. Clearly, Earth is doomed.
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Old 09-13-2019, 03:17 PM
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I've just finished watching a retrospective review of the 2005 'War of the World's. I log onto the SD to see this.

Permission to panic?
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Old 09-13-2019, 03:27 PM
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C'mon Rama.
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Old 09-13-2019, 03:37 PM
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I've just finished watching a retrospective review of the 2005 'War of the World's. I log onto the SD to see this.

Permission to panic?
Several kilometers wide, (2-16, per the wiki) and already moving at 41 km/s plus. It would sting. Ballpark 10 Teraton impact energy. Per the impact calculator I got that from, we get hit by such objects every 30 million years or so. 30-40 mile across crater.

Good thing it's closest point of approach is around 300 million km.

Interesting that it's almost directly in plane with the Milky Way. I wonder what sort of stellar cataclysm sent it our way? And from where?

Also interesting that this should radically change the estimated probability of extrasolar objects entering our system. I remember a few years ago here, asking IIRC, Ann Hedonia (an astrophysicist Doper if it wasn't that exact poster) on the topic of solar objects colliding with the Earth, 'Well, what about objects coming from outside the Solar System?' and being told we haven't seen any. Now we've seen two.
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Old 09-13-2019, 04:28 PM
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MEBuckner, interesting combo of post and sig line.
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Old 09-13-2019, 04:30 PM
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Man, you let one in and there goes the whole neighborhood.
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Old 09-13-2019, 04:31 PM
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Also interesting that this should radically change the estimated probability of extrasolar objects entering our system. I remember a few years ago here, asking IIRC, Ann Hedonia (an astrophysicist Doper if it wasn't that exact poster) on the topic of solar objects colliding with the Earth, 'Well, what about objects coming from outside the Solar System?' and being told we haven't seen any. Now we've seen two.
See this post from a earlier thread. From the Wikipedia link in the post, there should be around 10,000 interstellar objects 100 meters or larger inside the orbit of Neptune at any given moment.

Last edited by Darren Garrison; 09-13-2019 at 04:33 PM.
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Old 09-13-2019, 04:40 PM
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C'mon Rama.
The Ramans do everything in threes.
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Old 09-13-2019, 04:57 PM
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See this post from a earlier thread. From the Wikipedia link in the post, there should be around 10,000 interstellar objects 100 meters or larger inside the orbit of Neptune at any given moment.
Thanks for the thread and the cite. Interesting to think about.

I'd guess the actual concentration within the gravitational influence of Sol (or any other star) would be greater than that in the cite, which I'm guessing assumes a uniform distribution throughout interstellar space?

Given the Solar System moves relative to the Milky Way at 220 km/s, though relative to which part of the Milky Way isn't specified, I'd imagine we should expect extrasolar objects to have much higher relative velocities than the two we know of.

Which is a sobering thought. Never mind the drastically greater impact energy from something around 200 km/s vs past impacts, increased velocity means decreased warning time, and increased force on the object to enable a miss.
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Old 09-13-2019, 09:30 PM
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Given the Solar System moves relative to the Milky Way at 220 km/s, though relative to which part of the Milky Way isn't specified
That isn't a good way of putting it. More accurate is to say that the Sun's orbital speed around the center of the Milky Way at its orbital distance is 200 km/s. The typical orbital speed of other objects at the same distance? 200 km/s. Some a little more, some a little less, but it is like two cars on a race track, one traveling at 250 mph and the other traveling at 245 mph, and they collide. What happens? Nothing much, because their relative speed to each other is 5 mph. It would be a rare and extraordinary circumstance for race cars to meet at full speeds and going in opposite directions, and the same is true of interstellar objects.
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Old 09-13-2019, 09:35 PM
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MEBuckner, interesting combo of post and sig line.
Well, yeah--They are not here to help!!1!



All kidding aside, one such object could be a fluke--maybe the Solar System only sees one interstellar object every million years, or ten million years, or whatever, and we just got lucky. Two events within a couple of years (assuming Comet Borisov is in fact confirmed to be interstellar) does rather imply that they are in fact pretty common. There didn't seem to be much chance of getting a probe to 'Oumuamua in time to visit it (let alone do anything like, say, return a sample), and it sounds like this new one is moving awfully fast to try anything with Borisov (IANARocketScientist) but if interstellar visitors are in fact pretty common then I do wonder how much of a stretch it would be to identify a suitable target and get something out there quickly enough to give it a good once over. That would certainly be very cool.
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Old 09-13-2019, 09:41 PM
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I'd guess the actual concentration within the gravitational influence of Sol (or any other star) would be greater than that in the cite, which I'm guessing assumes a uniform distribution throughout interstellar space?
Not really, because the gravitational influence of a star is tiny and space is gigantic. A mere 100,000 AUs out (around the outer distance of our Oort cloud) the Sun's gravity is 1/10,000,000,000th the strength at Earth orbit
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Old 09-13-2019, 11:16 PM
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Permission to panic?
Denied

Someone discovered what the universe is for and why it is here a couple-three years ago. This is just another manifestation.
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Old 09-13-2019, 11:31 PM
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I will be so embarrassed if they stop and ask for our leader.
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Old 09-14-2019, 12:18 AM
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"Aw, geeze, you guys caught us at kind of an awkward time here--maybe you could come back in a few half-lives of krypton-85?"
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Old 09-14-2019, 12:37 AM
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Interesting that it's almost directly in plane with the Milky Way.
Why wouldn’t it be? Given the shape of a spiral galaxy, and the general disposition of the star systems within in, shouldn’t most objects traveling from one star system to another be traveling within the spiral plane?

Now, if this were an intergalactic bit of debris... well, then there’d be a song about it.
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Old 09-14-2019, 04:46 AM
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I've just finished watching a retrospective review of the 2005 'War of the World's. I log onto the SD to see this.

Permission to panic?
Any chance you can link to said review?
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Old 09-14-2019, 08:04 AM
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I will be so embarrassed if they stop and ask for our leader.
At this point, alien mind control parasites would only improve things for humanity.
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Old 09-14-2019, 08:21 AM
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If only we had a space force to deal with these invasions!
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Old 09-14-2019, 10:08 AM
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Now, if this were an intergalactic bit of debris... well, then there’d be a song about it.
Not many good rhymes for "debris."

Last edited by Darren Garrison; 09-14-2019 at 10:10 AM.
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Old 09-14-2019, 10:37 AM
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I will be so embarrassed if they stop and ask for our leader.
I wonder how they’d respond to his offer to purchase their planet.
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Old 09-14-2019, 10:39 AM
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Especially when the check bounced.
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Old 09-14-2019, 10:52 AM
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C'mon Rama.
Quote:
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"Aw, geeze, you guys caught us at kind of an awkward time here--maybe you could come back in a few half-lives of krypton-85?"
We could also send the spiritual leader of Tibet to provide some balance. So it would be Rama, Lama, ding-dong.
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Old 09-14-2019, 11:01 AM
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I wonder how they’d respond to his offer to purchase their planet.
They're going to be really, really pissed when all the toilets turn up missing.
  #25  
Old 09-14-2019, 05:13 PM
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Any chance you can link to said review?
Sure

https://www.youtube.com/watch?v=O-uulmO5DAs&t=11s

Be aware though that I personally didn't think the reviewer had anything particularly interesting or insightful to say, and I disagree with many of his opinions. Although its certainly flawed I really liked the movie.
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