Scientists were surprised and delighted to detect -- for the first time -- an interstellar asteroid passing through our solar system. Additional observations brought more surprises: the object is cigar-shaped 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 is unlike any asteroid or comet observed in our solar system to date, and may provide new clues into how other solar systems formed.


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Asteroid 1I/2017 U1 was discovered Oct 19

by the NASA-funded Pan-STARRS1 telescope in Hawaii.

From its trajectory and speed, scientists determined

it came from outside our solar system.

It was a special day when this object was first discovered. We had been waiting for the discovery of an interstellar object for decades basically.

When I first heard about this interstellar object it was very exciting from a scientific point of view that finally there has been an actual observation of such an object.

This object is simply a piece of another solar system that was expelled and it has been traveling through interstellar space for - hundreds of millions of years, billions of years? We don't know.

A number of our survey projects and other observatories immediately turned their telescopes to take observations of this object.

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Additional observations reveal

the asteroid has an unusual shape.

From the observations we have so far, it looks like a very elongated object. Maybe about 1/4 mile in length.

That is a very unusual shape. We don't see that in our solar system. None of the asteroids in our solar system look like that. So it's very puzzling how it could have obtained this shape.

We think this object, 2017 U1 is very long, perhaps 400 meters or so long, and very narrow, skinny, perhaps about 40 meters in the other dimensions. That's a very unusual shape. We don't see that in our solar system. None of the asteroids in our solar system look like that. So it's very puzzling how it could have obtained this shape.

We also see that it's very reddish in color indicating it's been in space a long time and irradiated not only by our Sun but by other suns as well.

There's still quite a lot to learn about this interstellar object, in limited time because it's on its way out of the solar system.

It's fading very fast. It's a relatively small object so it's very dim. But we are continuing to try to use NASA assets like Hubble Space Telescope and Spitzer to take observations to determine more about its size and composition.

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The asteroid, named 'Oumuamua by discoverers,

poses no risk as it exits the solar system.

Of Hawaiian origin, the name 'Oumuamua means

messenger from afar arriving first.

NASA's planetary defense coordination office has a near Earth object observations program which funds efforts that survey the skies to look for near earth asteroids and to calculate their orbits and their trajectories and to determine if any of them might pose a hazard to Earth. And as part of doing that, some amazing discoveries can happen and the discovery of this interstellar object was one of them.

As our observational capabilities improve -- PanSTARRS has been getting better, other surveys have been getting better, there are new generation surveys that will come on line -- we will be detecting more of these in the future.

Credit slate #1 (I think a list of all the observatories mentioned in Karen's paper would be nice. Let me know if this works for you and Lindley):

Pan-STARRS is operated by the University of Hawai'i Institute for Astronomy

and funded by NASA's Near-Earth Object Observations Program

Additional observations and data provided by:

European Southern Observatory (ESO)

Canada-France-Hawaii Telescope (CFHT)


Gemini South Telescope

W. M. Keck Observatory

and others

Credit slate #2

Asteroid animation and graphic provided

by European Southern Observatory (ESO)/ M. Kornmesser


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