Posted on 11/23/2017 9:07:33 AM PST by EBH
Now, new data reveal the interstellar interloper to be a rocky, cigar-shaped object with a somewhat reddish hue. The asteroid, named ‘Oumuamua by its discoverers, is up to one-quarter mile (400 meters) long and highly-elongated—perhaps 10 times as long as it is wide. That aspect ratio is greater than that of any asteroid or comet observed in our solar system to date. While its elongated shape is quite surprising, and unlike asteroids seen in our solar system, it may provide new clues into how other solar systems formed.
The observations and analyses were funded in part by NASA and appear in the Nov. 20 issue of the journal Nature. They suggest this unusual object had been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with our star system.
“For decades we’ve theorized that such interstellar objects are out there, and now – for the first time – we have direct evidence they exist,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate in Washington. “This history-making discovery is opening a new window to study formation of solar systems beyond our own.”
Immediately after its discovery, telescopes around the world, including ESO’s Very Large Telescope in Chile and other observatories around the world were called into action to measure the object’s orbit, brightness and color. Urgency for viewing from ground-based telescopes was vital to get the best data.
Combining the images from the FORS instrument on the ESO telescope using four different filters with those of other large telescopes, a team of astronomers led by Karen Meech of the Institute for Astronomy in Hawaii found that ‘Oumuamua varies in brightness by a factor of ten as it spins on its axis every 7.3 hours. No known asteroid or comet from our solar system varies so widely in brightness, with such a large ratio between length and width. The most elongated objects we have seen to date are no more than three times longer than they are wide.
“This unusually big variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape,” said Meech. We also found that it had a reddish color, similar to objects in the outer solar system, and confirmed that it is completely inert, without the faintest hint of dust around it.”
These properties suggest that ‘Oumuamua is dense, comprised of rock and possibly metals, has no water or ice, and that its surface was reddened due to the effects of irradiation from cosmic rays over hundreds of millions of years.
A few large ground-based telescopes continue to track the asteroid, though it’s rapidly fading as it recedes from our planet. Two of NASA’s space telescopes (Hubble and Spitzer) are tracking the object the week of Nov. 20. As of Nov. 20, ‘Oumuamua is travelling about 85,700 miles per hour (38.3 kilometers per second) relative to the Sun. Its location is approximately 124 million miles (200 million kilometers) from Earth -- the distance between Mars and Jupiter – though its outbound path is about 20 degrees above the plane of planets that orbit the Sun. The object passed Mars’s orbit around Nov. 1 and will pass Jupiter’s orbit in May of 2018. It will travel beyond Saturn’s orbit in January 2019; as it leaves our solar system, ‘Oumuamua will head for the constellation Pegasus.
Observations from large ground-based telescopes will continue until the object becomes too faint to be detected, sometime after mid-December. NASA’s Center for Near-Earth Object Studies (CNEOS) continues to take all available tracking measurements to refine the trajectory of 1I/2017 U1 as it exits our solar system.
This remarkable object was discovered Oct. 19 by the University of Hawaii’s Pan-STARRS1 telescope, funded by NASA’s Near-Earth Object Observations (NEOO) Program, which finds and tracks asteroids and comets in Earth’s neighborhood. NASA Planetary Defense Officer Lindley Johnson said, “We are fortunate that our sky survey telescope was looking in the right place at the right time to capture this historic moment. This serendipitous discovery is bonus science enabled by NASA’s efforts to find, track and characterize near-Earth objects that could potentially pose a threat to our planet.”
Preliminary orbital calculations suggest that the object came from the approximate direction of the bright star Vega, in the northern constellation of Lyra. However, it took so long for the interstellar object to make the journey – even at the speed of about 59,000 miles per hour (26.4 kilometers per second) -- that Vega was not near that position when the asteroid was there about 300,000 years ago.
While originally classified as a comet, observations from ESO and elsewhere revealed no signs of cometary activity after it slingshotted past the Sun on Sept. 9 at a blistering speed of 196,000 miles per hour (87.3 kilometers per second).
The object has since been reclassified as interstellar asteroid 1I/2017 U1 by the International Astronomical Union (IAU), which is responsible for granting official names to bodies in the solar system and beyond. In addition to the technical name, the Pan-STARRS team dubbed it ‘Oumuamua (pronounced oh MOO-uh MOO-uh), which is Hawaiian for “a messenger from afar arriving first.”
Astronomers estimate that an interstellar asteroid similar to ‘Oumuamua passes through the inner solar system about once per year, but they are faint and hard to spot and have been missed until now. It is only recently that survey telescopes, such as Pan-STARRS, are powerful enough to have a chance to discover them.
“What a fascinating discovery this is!” said Paul Chodas, manager of the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory, Pasadena, California. “It’s a strange visitor from a faraway star system, shaped like nothing we’ve ever seen in our own solar system neighborhood.”
It is a calculation based on assumptions. They assumed that there was no prior event that caused it’s current trajectory. Direct evidence would have been Actually seeing it in another galaxy, but as of right now that isn’t exactly possible.
Cheers,
“Almost certainly” is not direct evidence. If a bullet is buried in a tree we can calculate were it “May Have” come from, but a photo of the shooter would be “Direct Evidence”. In other words there may have been a prior collision that set it on it’s current course.
Cheers,
I have no idea what you're talking about.
When I was earning my B.S. in Physics (admittedly, a long time ago), I used to love "playing" with celestial mechanics.
This object had, at a certain position in space, a velocity greater than the Sun's escape velocity at that position. Apart from some unimaginable concatenation of events prior to that point in time (i.e., a series of extremely close swing-bys near the Gas / Ice Giants), that can only mean that the object was/is not in orbit around the Sun, but was/is rather on a hyperbolic trajectory.
It's really very simple reasoning.
Regards,
Scientists almost never expect to find "direct evidence."
Rather, several items of mutually-supporting indirect evidence are considered more than sufficient to work with.
Regards,
I am at the Ph.D. level and worked with Drs. Rosen ad Phillips, along with many others at HAC and Caltech/JP 1984 to 1992. My most fun project was the Galileo probe project.
Celestial Mechanics is theory that lays a foundation of ***understanding***. It’s important for understanding and for using as a foundation of modeling.
In applications and operations, all parameters or coefficients taken from theoretical equations become ***estimates***, and when they are time-dependent, they change with time. For example, pure Kepler equations are beautiful and effective under purely stable fixed conditions, but if there are any external perturbations, the predictive models become statistical models to account for such perturbations, for example leading to Monte Carlo estimated confidence geometry.
A specific example would be predicting the impact area on the Earth’s surface of say, the massive External Tank of the Space Shuttle. It is not possible to pinpoint the impact area precisely so a 95% confidence ellipse is estimated given the launch inputs. The algorithms to compute it work very well. But the basic model is a Kepler model which you may have studied in a physics book. When you take the next level to an operating real-time setting, the Kepler model needs a whole lot of massaging. But it’s a good starting point.
When calculating orbits of real objects in the planetary system, the same approach is taken to start with elementary models adding components to the equations to account for unknown effects. The modeling equations become statistical models. These unknown effects are modeled to minimize variation (2nd moment effects). So for example, the Sun’s unknown trajectory and the gravitational effects of other orbiting bodies are assumed to be reflected in these 2nd-moment data, and can oscillate over time as the object in focus is tracked. Changes in relative distances are plotted to 3D ‘banded’ trajectories referenced to the Sun. These banded trajectories are not lines or curves, they are more like tunnels where the object may be.
When the electronic sensors and pingers that track an object of interest are in operation, the data processing returns a ‘model’ of reality. Many assume incorrectly that what is viewed is reality, but it’s only a model of reality. The models are very accurate but sometimes models can be off, can break down due to limitations of the signal processing equipment. The young NASA engineers better know these limitations.
Tracking a natural object trajectory in the planetary system is different than say tracking the location of a Voyager satellite. The man-made satellite is designed to maintain or alter its trajectory to explore, to go where the controllers want it to go. The Voyager can escape the galaxy because it’s pulsed in a way that causes it to escape. A natural object may or may not escape. It may appear to have attained an escape velocity but other effects can alter that result over time. It may be that the object escapes, or it may be that other effects cause the object to change its trajectory. It could be the object follows an incredibly long orbit. Or it may be interstellar. The write-up and the reference to Nature do not pin down which it is.
I can’t tell you the seemingly countless times I found errors in modeling, in computational algorithms, in the interpretation of results. I have seen the faces of program managers grow anemic as they were shown errors that their programmers had checked dozens of times but had missed. In most cases, the actual errors were within the corrected error bounds giving the teams great relief. But in some cases, one in which I was involved, the program was reviewed for cancellation. The team I was on was feared as it should because review is necessary.
These youngsters at NASA are having fun calling out what appears to be a nice story. The nice story may be reality or may be fiction. We will have to wait and see.
I humbly bow to your superior intellect! (snicker!<)
No, sincerely - but I think that you are getting unnecessarily technical in your explanation, as well as being unnecessarily pessimistic.
Before continuing, let me express agreement with the accusation made earlier in this thread that newspaper journalists, of course, go for the juicier headline and are hence more than willing to obfuscate the facts to that end.
In short: The article could have easily presented some simple fact making it perfectly clear that - barring some unimaginably unlikely scenario (multiple perfectly choreographed fly-bys) - the object must be of interstellar origin.
A specific example would be predicting the impact area on the Earth’s surface of say, the massive External Tank of the Space Shuttle.
That's a poor example, depending as it does so heavily upon the influence of the Earth's atmosphere. In the case at hand (this putatively interstellar object) - unless it's a comet (which I'm willing to stipulate, but which you, for some reason, didn't care to come out and mention explicitly as a possible "deal-breaker" for the interstellar hypothesis) - simple Newtonian mechanics and Kepler's Laws should suffice, nicht wahr?
Again, I'm not a scientist and am not pretending to argue here with scientific rigor - just on a par with the usual level of discourse here at Free Republic.
My understanding (based on this sloppy article, which didn't bother to present the prima facie evidence I would have wished for and which I really believe might already be available) is that the object had, at a point in space where the escape velocity of the Sun was, say, "X," a velocity of "X + k," where "k" is a positive number.
Wouldn't you say that, in the context of a popular science article, and a Free Republic thread, it would then be permissible to assume that the object in question is indeed extra-solar?
Regards,
> “No, sincerely - but I think that you are getting unnecessarily technical in your explanation, as well as being unnecessarily pessimistic.”
If you knew what the denizens of NASA do on a daily basis, you would understand better. There’s a reason why they are under constant threat of the budget ax. In order to return them to prestige, they claim more funding is needed and grander missions. That is not what they need. They need harsh oversight in a course where the tough survivors are rewarded greatly, making it Olympian to even gain employment in the agency, the way it was once.
NASA like so many other agencies of the federal government is overrun by political correctness. You should be skeptical of anything and everything they publish and claim to produce. Call them on the carpet and put them to the test. If they can’t take the pressure, let them quit.
Exactly! So it should not be called Direct Evidence as though it was a Detective Show. Most likely the scientists did not put that way, only the writer.
Cheers,
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