A Comet from the Stars?

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Michael Watson

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Message 1897492 - Posted: 25 Oct 2017, 23:29:34 UTC
Last modified: 25 Oct 2017, 23:41:01 UTC

A comet has been observed for six days, with a substantially hyperbolic orbit (eccentricity 1.18). This suggests that it may not be in orbit of the Sun, but merely passing through our part of space.

If the hyperbolic orbit is confirmed by further observations, it will mark the first time that such an interstellar visitor has been discovered.

There appear to be no signs that the orbit of this object has been perturbed by a near pass at any of the major planets. Such passes can alter the elliptical orbits of ordinary comets, sending them off into the void, for good.
Conversely, an interstellar comet could have been thrown our way by just such an encounter within its own star system.
Below find a link to an article with more details on this newly discovered comet.

http://www.skyandtelescope.com/astronomy-news/astronomers-spot-first-known-interstellar-comet
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Michael Watson

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Message 1897606 - Posted: 26 Oct 2017, 18:03:24 UTC
Last modified: 26 Oct 2017, 18:08:29 UTC

After very careful observation at the Very Large Telescope found no cometary emissions whatever, the object has been redesignated an asteroid: A/2017 U1. They believe it passed nearest the Sun on September 9, and within 15 million miles of Earth on October 14.

The supposition that the object came from outside our solar system has been strengthened by further observations. The eccentricity is now calculated as 1.19, whereas before it was 1.18 .

The greatest hyperbolic eccentricity seen in a solar system object before was 1.057, which was caused by an encounter with a major planet. It was not considered an indication that the object came from outside our solar system

Please find below a link to an article on the newly classified object:

https://en.wikipedia.org/wiki/A/2017_U1
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Message 1897707 - Posted: 27 Oct 2017, 5:44:22 UTC

A/2017 U1 (previously C/2017 U1 (PANSTARRS)) is a potentially interstellar object passing through the Solar System. It was discovered on extremely hyperbolic orbit on October 18, 2017 by the Pan-STARRS telescope, when the object was 0.2 AU (30,000,000 km; 19,000,000 mi) from Earth. Initially thought to be a comet, it was reclassified as an asteroid a week later.

Based on the first 2 weeks of observations, 2017 U1's orbital eccentricity is 1.1922 ± 0.00268, the highest of any known object in the Solar System.[2] The previous record holder was C/1980 E1 with an eccentricity of 1.057.[4] The high eccentricity both inbound and outbound indicates that it is not gravitationally bound to the Solar System and is likely an interstellar object.

Interesting object !!
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Message 1897718 - Posted: 27 Oct 2017, 7:36:04 UTC - in response to Message 1897707.  

A Very Interesting object for sure!!!
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Michael Watson

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Message 1897761 - Posted: 27 Oct 2017, 17:07:53 UTC

No coma could be found around the object, which is why it was reclassified from a comet to an asteroid. It may have existed inside the 'snowline' of its star system, and lost any water it had by sublimation, over time.

The object could have been ejected from its system, and sent our way by interaction with a major planet. This might have been a near-in 'hot Jupiter'. Otherwise, inner system interactions, such as occur in our solar system, are reportedly considered unlikely to accomplish such an ejection.
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Message 1897833 - Posted: 28 Oct 2017, 7:07:19 UTC - in response to Message 1897761.  

More on this asteroid? Hope they find where it came from.


First Rock From Outside the Solar System Sails Past Earth





A/2017 U1 is most likely of interstellar origin. Approaching from above, it was closest to the sun on September 9. Traveling at 27 miles per second (44 kilometers per second), the comet is headed away from Earth and the sun on its way out of the solar system.
Courtesy NASA, JPL-Caltech
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Michael Watson

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Message 1898278 - Posted: 30 Oct 2017, 16:18:32 UTC
Last modified: 30 Oct 2017, 16:21:29 UTC

dp
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Michael Watson

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Message 1898279 - Posted: 30 Oct 2017, 16:19:37 UTC

SETIQuest info, the website of the SETI Institute's Allen Telescope Array, has the following in it observer notes, for October 30:

"Calibrating to observe A/2017 U1, the mysterious object that has entered the solar system. 1 GHz to 2 GHz tonight." The latter was revised to 1 to 3 GHz, later.
Please find a link to this website, below:

http://www.setiquest.info
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Michael Watson

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Message 1898535 - Posted: 1 Nov 2017, 16:28:37 UTC

Observer notes at SETIQuestinfo report that the hyperbolic object A/2017 U1 will be observed again tonight at the Allen Telescope Array, in the range 1 to 2 GHz. Asteroids are not known sources of radio waves, so they appear to be considering the possibility that the object is something else altogether.
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Message 1898545 - Posted: 1 Nov 2017, 18:13:29 UTC

It was sighted by optical telescopes. No other radiotelescope besides the ATA seems to have observed it. Maybe Arecibo, if in working order, could have used its radar capabilities. On the NASA site there is no news about a possible use of the Goldstone radar to track it.
Tullio
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Message 1898550 - Posted: 1 Nov 2017, 18:37:07 UTC - in response to Message 1898545.  
Last modified: 1 Nov 2017, 18:39:03 UTC

If I understand correctly, the Allen Telescope Array is not set up to emit radio waves, which can be used for asteroid tracking purposes, like Arecibo, and Goldstone. The reasonable inference seems to be that they are listening for intelligent signals from A/2017 U1.
It's obviously a very long shot that the object is not an asteroid, but a space vessel. Still, they seem to find it worth the effort to repeatedly test this hypothesis.
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Message 1898619 - Posted: 2 Nov 2017, 4:15:11 UTC - in response to Message 1898550.  

The trajectory of the object does look similar to a sling shot around the sun to give it some oomph on it's journey. But if it was a spaceship, then they would be able to detect life on earth and would likely have stopped and had a look, so I plump for a large asteroid or comet looking at the ellipse path printed so far wouldn't some sort of extrapolation give the far end of its path before returning again?
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Message 1898635 - Posted: 2 Nov 2017, 6:42:19 UTC

I think that the trajectory is a hyperbola, not an ellipse.
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Message 1898824 - Posted: 3 Nov 2017, 4:48:10 UTC - in response to Message 1898619.  

The trajectory of the object does look similar to a sling shot around the sun to give it some oomph on it's journey. But if it was a spaceship, then they would be able to detect life on earth and would likely have stopped and had a look, so I plump for a large asteroid or comet looking at the ellipse path printed so far wouldn't some sort of extrapolation give the far end of its path before returning again?

If it were an alien space ship using the sun for a speed boost and a course correction and if they detected us maybe,since this is not their destination, they are unable to slow down and check us out. Or better yet, they don't think our presence warrants any investigation. That was the main point in the original book by Arthur C. Clarke Rendezvous with Rama.
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Message 1901557 - Posted: 17 Nov 2017, 17:21:19 UTC
Last modified: 17 Nov 2017, 17:33:23 UTC

They are now saying that the hyperbolic asteroid is about 30 meters wide by 180 meters long. This is based on the variability in the amount of light it reflects as it spins. That's a remarkably long, thin object, six times longer than its width. The longest, thinest asteroids found to reside in our solar system have less than half of that length to width ratio.
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Message 1901581 - Posted: 17 Nov 2017, 21:15:56 UTC - in response to Message 1901557.  

They are now saying that the hyperbolic asteroid is about 30 meters wide by 180 meters long. This is based on the variability in the amount of light it reflects as it spins. That's a remarkably long, thin object, six times longer than its width. The longest, thinest asteroids found to reside in our solar system have less than half of that length to width ratio.

Still not large enough to be a manned interstellar space ship, but maybe an unmanned probe of some sort. OK, that was a total fantasy.
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Message 1901588 - Posted: 17 Nov 2017, 22:08:33 UTC
Last modified: 17 Nov 2017, 22:25:54 UTC

I don't quite see how we could know the necessary size an interstellar spacecraft, tenanted or otherwise.

One naturally wonders how an asteroid would assume such a shape; about the proportions of a thick cigar. An asteroid like Kleopatra appears to have stretched itself by spinning rapidly, but still managed less than a 3 to1 length to width ratio.

Toutatis, spinning much slower, pulled two asteroids together to make one, the result: a length /width ratio of less than 2.5 to 1.

Why have none longer been found? One suspects that they either pulled themselves apart , into two distinct asteroids, or that the coincidence of three or more asteroids becoming joined, end to end, was too improbable to be expected, or that it was too unstable a configuration.
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Message 1901606 - Posted: 18 Nov 2017, 0:33:51 UTC - in response to Message 1901588.  

Consider the A380 Airbus body specs of 73m long x 7m wide, a ratio of 10:1, sounds more like a probe or just an odd shape of asteroid.
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Message 1901672 - Posted: 18 Nov 2017, 8:33:50 UTC - in response to Message 1901588.  

don't quite see how we could know the necessary size an interstellar spacecraft, tenanted or otherwise.
Quite agree Michael. Arthur C. Clarke decided that Rama was to be 20Km in diameter x 54Km long, a ratio of nearly 2 1/2 to one. But that was just his idea in a sci fi book.
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Message 1901742 - Posted: 18 Nov 2017, 20:58:32 UTC - in response to Message 1901672.  

It now has name.


Interstellar asteroid is given a name


The first known asteroid to visit our Solar System from interstellar space has been given a name.


Scientists who have studied its speed and trajectory believe it originated in a planetary system around another star.

The interstellar interloper will now be referred to as 'Oumuamua, which means "a messenger from afar arriving first" in Hawaiian.

The name reflects the object's discovery by a Hawaii-based astronomer using an observatory on Maui.

It was discovered on 19 October this year by Rob Weryk, a postdoctoral researcher at the University of Hawaii Institute for Astronomy.
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Message boards : Science (non-SETI) : A Comet from the Stars?


 
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