posted 10-27-2017 12:50 PM               

The object, known as A/2017 U1, was detected last week by researchers using the Pan-STARRS 1 telescope in Hawaii.

"We have been waiting for this day for decades," Paul Chodas, manager of the Center for Near-Earth Object Studies at the NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement.

"It's long been theorized that such objects exist — asteroids or comets moving around between the stars and occasionally passing through our solar system — but this is the first such detection," Chodas added. "So far, everything indicates this is likely an interstellar object, but more data would help to confirm it."

Chodas and other researchers base this preliminary conclusion on A/2017 U1's hyperbolic orbit — the fact that its path is taking the body out of the solar system.

posted 11-09-2017 05:37 PM            

Lyra is the star constellation from which the interstellar asteroid A/2017 U1 came from. According to current information, the object is smaller than 400m in diameter and is currently traveling at 44km/s with respect to the sun, much faster than any human-made object to date.

posted 11-20-2017 10:48 AM               

ESO Observations Show First Interstellar Asteroid is Like Nothing Seen Before

VLT reveals dark, reddish and highly-elongated object

For the first time ever astronomers have studied an asteroid that has entered the Solar System from interstellar space. Observations from ESO's Very Large Telescope in Chile and other observatories around the world show that this unique object was traveling through space for millions of years before its chance encounter with our star system. It appears to be a dark, reddish, highly-elongated rocky or high-metal-content object. The new results appear in the journal Nature on 20 November 2017.

On 19 October 2017, the Pan-STARRS 1 telescope in Hawai'i picked up a faint point of light moving across the sky. It initially looked like a typical fast-moving small asteroid, but additional observations over the next couple of days allowed its orbit to be computed fairly accurately. The orbit calculations revealed beyond any doubt that this body did not originate from inside the Solar System, like all other asteroids or comets ever observed, but instead had come from interstellar space. Although originally classified as a comet, observations from ESO and elsewhere revealed no signs of cometary activity after it passed closest to the Sun in September 2017. The object was reclassified as an interstellar asteroid and named 1I/2017 U1 (ʻOumuamua).

"We had to act quickly," explains team member Olivier Hainaut from ESO in Garching, Germany. "ʻOumuamua had already passed its closest point to the Sun and was heading back into interstellar space."

ESO's Very Large Telescope was immediately called into action to measure the object's orbit, brightness and colour more accurately than smaller telescopes could achieve. Speed was vital as ʻOumuamua was rapidly fading as it headed away from the Sun and past the Earth's orbit, on its way out of the Solar System. There were more surprises to come.

Combining the images from the FORS instrument on the VLT using four different filters with those of other large telescopes, the team of astronomers led by Karen Meech (Institute for Astronomy, Hawai'i, USA) found that ʻOumuamua varies dramatically in brightness by a factor of ten as it spins on its axis every 7.3 hours.

Karen Meech explains the significance: "This unusually large variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape. We also found that it has a dark red colour, 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 ʻOumuamua is dense, possibly rocky or with high metal content, lacks significant amounts of water or ice, and that its surface is now dark and reddened due to the effects of irradiation from cosmic rays over millions of years. It is estimated to be at least 400 metres long.

Preliminary orbital calculations suggested that the object had come from the approximate direction of the bright star Vega, in the northern constellation of Lyra. However, even travelling at a breakneck speed of about 95 000 kilometres/hour, it took so long for the interstellar object to make the journey to our Solar System that Vega was not near that position when the asteroid was there about 300 000 years ago. ʻOumuamua may well have been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with the Solar System.

Astronomers estimate that an interstellar asteroid similar to ʻOumuamua passes through the inner Solar System about once per year, but they are faint and hard to spot so 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.

"We are continuing to observe this unique object," concludes Olivier Hainaut, "and we hope to more accurately pin down where it came from and where it is going next on its tour of the galaxy. And now that we have found the first interstellar rock, we are getting ready for the next ones!"

posted 11-20-2017 10:51 AM               

New Designation Scheme for Interstellar Objects

The discovery of A/2017 U1 has presented a slight nomenclature problem. Since both the original and future barycentric orbits for this object are significantly hyperbolic, this object is not bound to our solar system and the current apparition is likely to be the only time that the object is observable.

Due to the unique nature of this object, there is pressure to assign a name. The minor-planet designation scheme does not allow a name to be assigned to this object based on the brief arc of observation.

Recent e-mail exchanges between the IAU General Secretary, the IAU Division F President, the co-chairs of the IAU Working Group on Small Body Nomenclature and the Minor Planet Center have discussed this nomenclature issue. A solution has been proposed that solves the problem. A new series of small-body designations for interstellar objects will be introduced: the I numbers. This new sequence will be similar in form to the comet numbering system and assignment of the numbers will be handled by the Minor Planet Center.

Provisional designations for interstellar objects will be handled using the C/ or A/ prefix (as appropriate), with the designation using the comet system.

Accordingly, the object A/2017 U1 receives the permanent designation 1I and the name ʻOumuamua. The name, which was chosen by the Pan-STARRS team, is of Hawaiian origin and reflects the way this object is like a scout or messenger sent from the distant past to reach out to us (ʻou means reach out for, and mua, with the second mua placing emphasis, means first, in advance of).

Correct forms for referring to this object are therefore: 1I; 1I/2017 U1; 1I/ʻOumuamua; and 1I/2017 U1 (ʻOumuamua).

This first interstellar object is being handled as a special case. A small committee of the WGSBN will be created to codify the circumstances under which an object will qualify for an I-number and the rules that will apply to the names, bearing in mind the precedent set by this case. A formal report will follow their deliberations.

posted 11-28-2017 08:24 PM               

If you want to learn the answers to more "how do you know"-type questions about 'Oumuamua, check out this awesome NASA FAQ. But if you want to calculate some answers for yourself — well, just keep reading.

posted 12-12-2017 03:54 AM               

So far limited observations of 'Oumuamua, using facilities such as the SETI Institute's Allen Telescope Array, have turned up nothing. But this Wednesday at 3 p.m. Eastern time, the Breakthrough Listen project will aim the West Virgina-based 100-meter Green Bank Telescope at 'Oumuamua for 10 hours of observations in a wide range of radio frequencies, scanning the object across its entire rotation in search of any signals.

posted 12-13-2017 09:08 PM               

quote:

---

Originally posted by SpaceAholic:
Scientists are about to listen very closely for radio signals from our solar system's first known interstellar visitor...

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posted 12-14-2017 11:18 AM               

Breakthrough Listen Releases Initial Results and Data from Observations of 'Oumuamua

No evidence of artificial signals emanating from the object so far detected by the Green Bank Telescope, but monitoring and analysis continue. Initial data are available for public inspection in the Breakthrough Listen archive.

Breakthrough Listen – the initiative to find signs of intelligent life in the universe – is reporting preliminary results and making initial data available from its observations of the "interstellar visitor" 'Oumuamua.

The initial block of observations (the first of a planned four blocks) ran from 3:45pm to 9:45pm ET on Wednesday, December 13, using the Breakthrough Listen backend instrument on the Robert C. Byrd Green Bank Telescope in West Virginia. Listen observed 'Oumuamua across four radio bands (corresponding to four of the radio receivers available at Green Bank, denoted L, S, X, and C), spanning billions of individual channels across the 1 to 12 GHz range.

In addition to calibration observations, the instrument accumulated 90 TB of raw data over a 2 hour observation of 'Oumuamua itself. A search for signals that may be of artificial origin has begun, but despite the impressive computational power of the Breakthrough Listen computing cluster at Green Bank, the large data volumes mean that this will take some time to complete.

"It is great to see data pouring in from observations of this novel and interesting source," said Andrew Siemion, Director of Berkeley SETI Research Center. "Our team is excited to see what additional observations and analyses will reveal"

The Breakthrough Listen "turboSETI" pipeline combs the data for narrow bandwidth signals that are drifting in frequency. By matching the rate at which these signals drift to the expected drift due to the motion of 'Oumuamua (in addition to rejecting interfering signals from human technology that do not match the sky position of the primary target), the software attempts to identify any signals that might be coming from 'Oumuamua itself.

No such signals have been detected, although the analysis is not yet complete. So far, data from the S-band receiver (covering frequencies from 1.7 to 2.6 GHz) has been processed, and analysis of the remaining three bands is ongoing. A subset of the S-band data is now available for public inspection in the Breakthrough Listen archive, and additional data will be added as it becomes available.

The data is stored in specialized formats, and analyzing it may be challenging for non-experts. We invite those who are interested to study the tutorial material provided by the Breakthrough Listen science team at the University of California, Berkeley, SETI Research Center and to assist with the analysis not only of this intriguing object, but of the entire Breakthrough Listen dataset.

posted 12-14-2017 11:22 AM               

quote:

---

Originally posted by Philip:
Any ideas if the 300m Arecibo dish on Puerto Rico was used to analyze the shape of this thing?

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posted 06-28-2018 07:02 AM               

Careful observations of 'Oumuamua's orbit showed that as the object flew through space, something continually nudged it a tiny bit farther from the Sun than expected. That something was probably ice that warmed up and sprayed gas into space. This process is characteristic of a comet, rather than an asteroid, even though 'Oumuamua never displayed the glorious tail of gas and dust that accompanies most comets.

"It's an unusual comet, and that's pretty exciting," says Karen Meech, an astronomer at the University of Hawaii in Honolulu. She and her colleagues, led by astronomer Marco Micheli of the European Space Agency in Frascati, Italy, report the discovery on 27 June in Nature.

posted 06-28-2018 12:24 PM            

...as the object flew through space, something continually nudged it a tiny bit farther from the Sun than expected. That something was probably ice that warmed up and sprayed gas into space.

posted 11-02-2018 07:59 PM               

...there has also been some speculation that based on its shape, 'Oumuamua might actually be an interstellar spacecraft (Breakthrough Listen even monitored it for signs of radio signals!). A new study by a pair of astronomers from the Harvard Smithsonian Center for Astrophysics (CfA) has taken it a step further, suggesting that 'Oumuamua may actually be a light sail of extra-terrestrial origin.

The study – "Could Solar Radiation Pressure Explain 'Oumuamua's Peculiar Acceleration?", which recently appeared online – was conducted by Shmuel Bialy and Prof. Abraham Loeb. Whereas Bialy is a postdoctoral researcher at the CfA's Institute for Theory and Computation (ITC), Prof. Loeb is the director of the ITC, the Frank B. Baird Jr. Professor of Science at Harvard University, and the head chair of the Breakthrough Starshot Advisory Committee.

posted 11-16-2018 07:50 AM               

NASA Learns More About Interstellar Visitor 'Oumuamua

In November 2017, scientists pointed NASA's Spitzer Space Telescope toward the object known as 'Oumuamua — the first known interstellar object to visit our solar system. The infrared Spitzer was one of many telescopes pointed at 'Oumuamua in the weeks after its discovery that October.

'Oumuamua was too faint for Spitzer to detect when it looked more than two months after the object's closest aproach to Earth in early September. However, the "non-detection" puts a new limit on how large the strange object can be. The results are reported in a new study published Nov. 14 in the Astronomical Journal and coauthored by scientists at NASA's Jet Propulsion Laboratory in Pasadena, California.

The new size limit is consistent with the findings of a research paper published earlier this year, which suggested that outgassing was responsible for the slight changes in 'Oumuamua's speed and direction as it was tracked last year: The authors of that paper conclude the expelled gas acted like a small thruster gently pushing the object. That determination was dependent on 'Oumuamua being relatively smaller than typical solar system comets. (The conclusion that 'Oumuamua experienced outgassing suggested that it was composed of frozen gases, similar to a comet.)

"'Oumuamua has been full of surprises from day one, so we were eager to see what Spitzer might show," said David Trilling, lead author on the new study and a professor of astronomy at Northern Arizona University. "The fact that 'Oumuamua was too small for Spitzer to detect is actually a very valuable result."

'Oumuamua was first detected by the University of Hawaii's Pan-STARRS 1 telescope on Haleakala, Hawaii (the object's name is a Hawaiian word meaning "visitor from afar arriving first"), in October 2017 while the telescope was surveying for near-Earth asteroids.

Subsequent detailed observations conducted by multiple ground-based telescopes and NASA's Hubble Space Telescope detected the sunlight reflected off 'Oumuamua's surface. Large variations in the object's brightness suggested that 'Oumuamua is highly elongated and probably less than half a mile (2,600 feet, or 800 meters) in its longest dimension.

But Spitzer tracks asteroids and comets using the infrared energy, or heat, that they radiate, which can provide more specific information about an object's size than optical observations of reflected sunlight alone would.

The fact that 'Oumuamua was too faint for Spitzer to detect sets a limit on the object's total surface area. However, since the non-detection can't be used to infer shape, the size limits are presented as what 'Oumuamua's diameter would be if it were spherical. Using three separate models that make slightly different assumptions about the object's composition, Spitzer's non-detection limited 'Oumuamua's "spherical diameter" to 1,440 feet (440 meters), 460 feet (140 meters) or perhaps as little as 320 feet (100 meters). The wide range of results stems from the assumptions about 'Oumuamua's composition, which influences how visible (or faint) it would appear to Spitzer were it a particular size.

Small but Reflective

The new study also suggests that 'Oumuamua may be up to 10 times more reflective than the comets that reside in our solar system — a surprising result, according to the paper's authors. Because infrared light is largely heat radiation produced by "warm" objects, it can be used to determine the temperature of a comet or asteroid; in turn, this can be used to determine the reflectivity of the object's surface — what scientists call albedo. Just as a dark T-shirt in sunlight heats up more quickly than a light one, an object with low reflectivity retains more heat than an object with high reflectivity. So a lower temperature means a higher albedo.

A comet's albedo can change throughout its lifetime. When it passes close to the Sun, a comet's ice warms and turns directly into a gas, sweeping dust and dirt off the comet's surface and revealing more reflective ice.

'Oumuamua had been traveling through interstellar space for millions of years, far from any star that could refresh its surface. But it may have had its surface refreshed through such "outgassing" when it made an extremely close approach to our Sun, a little more than five weeks before it was discovered. In addition to sweeping away dust and dirt, some of the released gas may have covered the surface of 'Oumuamua with a reflective coat of ice and snow — a phenomenon that's also been observed in comets in our solar system.

'Oumuamua is on its way out of our solar system — almost as far from the Sun as Saturn's orbit — and is well beyond the reach of any existing telescopes.

"Usually, if we get a measurement from a comet that's kind of weird, we go back and measure it again until we understand what we're seeing," said Davide Farnocchia, of the Center for Near Earth Object Studies (CNEOS) at JPL and a coauthor on both papers. "But this one is gone forever; we probably know as much about it as we're ever going to know."

posted 04-16-2019 10:53 PM               

A few minutes after 3 a.m. on January 9, 2014, a fireball burned through the skies just off the northeast coast of Papua New Guinea; it was a meteor disintegrating in Earth's atmosphere, as so many meteors do.

But according to new research, this early morning visitor wasn't just any old space rock going out with a bang. It was an interstellar interloper, a visitor launched into the cosmos from deep within another star system.

If confirmed, the meteor will be only the second such object ever spotted by humans.

posted 09-12-2019 01:45 PM               

First there was 'Oumuamua, discovered nearly two years ago. Now we might be in store for another interstellar flyby, this time by the recently discovered comet known for now by the provisional designation C/2019 Q4 (Borisov) — formerly gb00234.

posted 09-12-2019 03:23 PM               

Newly Discovered Comet Is Likely Interstellar Visitor

A newly discovered comet has excited the astronomical community this week because it appears to have originated from outside the solar system. The object - designated C/2019 Q4 (Borisov) - was discovered on Aug. 30, 2019, by Gennady Borisov at the MARGO observatory in Nauchnij, Crimea. The official confirmation that comet C/2019 Q4 is an interstellar comet has not yet been made, but if it is interstellar, it would be only the second such object detected. The first, 'Oumuamua, was observed and confirmed in October 2017.

The new comet, C/2019 Q4, is still inbound toward the Sun, but it will remain farther than the orbit of Mars and will approach no closer to Earth than about 190 million miles (300 million kilometers).

After the initial detections of the comet, Scout system, which is located at NASA's Jet Propulsion Laboratory in Pasadena, California, automatically flagged the object as possibly being interstellar. Davide Farnocchia of NASA's Center for Near-Earth Object Studies at JPL worked with astronomers and the European Space Agency's Near-Earth Object Coordination Center in Frascati, Italy, to obtain additional observations. He then worked with the NASA-sponsored Minor Planet Center in Cambridge, Massachusetts, to estimate the comet's precise trajectory and determine whether it originated within our solar system or came from elsewhere in the galaxy.

The comet is currently 260 million miles (420 million kilometers) from the Sun and will reach its closest point, or perihelion, on Dec. 8, 2019, at a distance of about 190 million miles (300 million kilometers).

"The comet's current velocity is high, about 93,000 mph [150,000 kph], which is well above the typical velocities of objects orbiting the Sun at that distance," said Farnocchia. "The high velocity indicates not only that the object likely originated from outside our solar system, but also that it will leave and head back to interstellar space."

Currently on an inbound trajectory, comet C/2019 Q4 is heading toward the inner solar system and will enter it on Oct. 26 from above at roughly a 40-degree angle relative to the ecliptic plane. That's the plane in which the Earth and planets orbit the Sun.

C/2019 Q4 was established as being cometary due to its fuzzy appearance, which indicates that the object has a central icy body that is producing a surrounding cloud of dust and particles as it approaches the Sun and heats up. Its location in the sky (as seen from Earth) places it near the Sun - an area of sky not usually scanned by the large ground-based asteroid surveys or NASA's asteroid-hunting NEOWISE spacecraft.

C/2019 Q4 can be seen with professional telescopes for months to come. "The object will peak in brightness in mid-December and continue to be observable with moderate-size telescopes until April 2020," said Farnocchia. "After that, it will only be observable with larger professional telescopes through October 2020."

Observations completed by Karen Meech and her team at the University of Hawaii indicate the comet nucleus is somewhere between 1.2 and 10 miles (2 and 16 kilometers) in diameter. Astronomers will continue collect observations to further characterize the comet's physical properties (size, rotation, etc.) and also continue to better identify its trajectory.

The Minor Planet Center is hosted by the Harvard-Smithsonian Center for Astrophysics and is a sub-node of NASA's Planetary Data System Small Bodies Node at the University of Maryland. JPL hosts the Center for Near-Earth Object Studies. All are projects of NASA's Near-Earth Object Observations Program and elements of the agency's Planetary Defense Coordination Office within NASA's Science Mission Directorate.

posted 09-24-2019 08:05 PM               

Naming of New Interstellar Visitor: 2I/Borisov

On 30 August 2019 the amateur astronomer Gennady Borisov, from MARGO observatory, Crimea, discovered an object with a comet-like appearance. The object has a condensed coma, and more recently a short tail has been observed. Mr. Borisov made this discovery with a 0.65-metre telescope he built himself.

After a week of observations by amateur and professional astronomers all over the world, the IAU Minor Planet Center was able to compute a preliminary orbit, which suggested this object was interstellar — only the second such object known to have passed through the Solar System.

The orbit is now sufficiently well known, and the object is unambiguously interstellar in origin; it has received its final designation as the second interstellar object, 2I. In this case, the IAU has decided to follow the tradition of naming cometary objects after their discoverers, so the object has been named 2I/Borisov.

Of the thousands of comets discovered so far, none has an orbit as hyperbolic as that of 2I/Borisov. This conclusion is independently supported by the NASA JPL Solar System Dynamics Group. Coming just two years after the discovery of the first interstellar object 1I/'Oumuamua, this new finding suggests that such objects may be sufficiently numerous to provide a new way of investigating processes in planetary systems beyond our own.

2I/Borisov will make its closest approach to the Sun (reach its perihelion) on 7 December 2019, when it will be 2 astronomical units (AU) from the Sun and also 2 AU from Earth. By December and January it is expected that it will be at its brightest in the southern sky. It will then begin its outbound journey, eventually leaving the Solar System forever.

Astronomers are eagerly observing this object, which will be continuously observable for many months, a period longer than that of its predecessor, 1I/'Oumuamua. Astronomers are optimistic about their chances of studying this rare guest in great detail.

Estimates of the sizes of comets are difficult because the small cometary nucleus is embedded in the coma, but, from the observed brightness, 2I/Borisov appears to be around a few kilometers in diameter. One of the largest telescopes in the world, the 10.4m Gran Telescopio Canarias in the Canary Islands, has already obtained a spectrum of 2I/Borisov and has found it to resemble those of typical cometary nuclei.

This new interstellar visitor raises intriguing questions: Why have interstellar objects not been discovered before? What is the expected rate of their appearance in the inner Solar System? How do such objects compare to similar bodies within the Solar System? Large telescopic surveys capable of scanning large fractions of the sky on a regular basis may help to answer these questions and more in the near future.

posted 10-17-2019 08:39 AM               

Hubble Observes 1st Confirmed Interstellar Comet

NASA's Hubble Space Telescope has given astronomers their best look yet at an interstellar visitor — comet 2I/Borisov — whose speed and trajectory indicate it has come from beyond our solar system.

This Hubble image, taken on Oct. 12, 2019, is the sharpest view of the comet to date. Hubble reveals a central concentration of dust around the nucleus (which is too small to be seen by Hubble).

Comet 2I/Borisov is only the second such interstellar object known to have passed through the solar system. In 2017, the first identified interstellar visitor, an object officially named 'Oumuamua, swung within 24 million miles of the Sun before racing out of the solar system. "Whereas 'Oumuamua appeared to be a rock, Borisov is really active, more like a normal comet. It's a puzzle why these two are so different," said David Jewitt of the University of California, Los Angeles (UCLA), leader of the Hubble team who observed the comet.

As the second known interstellar object found to enter our solar system, the comet provides invaluable clues to the chemical composition, structure and dust characteristics of planetary building blocks presumably forged in an alien star system a long time ago and far away.

"Though another star system could be quite different from our own, the fact that the comet's properties appear to be very similar to those of the solar system's building blocks is very remarkable," said Amaya Moro-Martin of the Space Telescope Science Institute in Baltimore.

Hubble photographed the comet at a distance of 260 million miles from Earth. The comet is falling past the Sun and will make its closest approach to the Sun on Dec. 7, 2019, when it will be twice as far from the Sun as Earth.

The comet is following a hyperbolic path around the Sun, and currently is blazing along at an extraordinary speed of 110,000 miles per hour. "It's traveling so fast it almost doesn't care that the Sun is there," said Jewitt.

By the middle of 2020 the comet will streak past Jupiter's distance of 500 million miles on its way back into interstellar space where it will drift for untold millions of years before skirting close to another star system.

Above: Hubble photographed comet 2I/Borisov at a distance of 260 million miles from Earth. This Hubble image, taken on Oct. 12, 2019, is the sharpest view to date of the comet. Hubble reveals a central concentration of dust around the nucleus (which is too small to be seen by Hubble). The comet is falling toward the Sun and will make its closest approach on Dec. 7, 2019, when it will be twice as far from the Sun as Earth. The comet is following a hyperbolic path around the Sun and will exit back into interstellar space. (NASA, ESA and D. Jewitt/UCLA)

Crimean amateur astronomer Gennady Borisov discovered the comet on Aug. 30, 2019. After a week of observations by amateur and professional astronomers all over the world, the International Astronomical Union's Minor Planet Center and the Center for Near-Earth Object Studies at NASA's Jet Propulsion Laboratory in Pasadena, California, computed a trajectory for the comet, which confirms that it came from interstellar space.

Until now, all cataloged comets have come from either a ring of icy debris at the periphery of our solar system, called the Kuiper belt, or the hypothetical Oort cloud, a shell of comets about a light-year from the Sun, defining the dynamical edge of our solar system.

Borisov and 'Oumuamua are only the beginning of the discoveries of interstellar objects paying a brief visit to our solar system, say researchers. According to one study there are thousands of such interlopers here at any given time, though most are too faint to be detected with current-day telescopes.

Observations by Hubble and other telescopes have shown that rings and shells of icy debris encircle young stars where planet formation is underway. A gravitational "pinball game" between these comet-like bodies or planets orbiting other stars can hurtle them deep into space where they go adrift among the stars.

Future Hubble observations of 2I/Borisov are planned through January 2020, with more being proposed.

"New comets are always unpredictable," said Max Mutchler, another member of the observing team. "They sometimes brighten suddenly or even begin to fragment as they are exposed to the intense heat of the Sun for the first time. Hubble is poised to monitor whatever happens next with its superior sensitivity and resolution."

posted 12-12-2019 12:34 PM               

Interstellar Comet 2I/Borisov Swings Past the Sun

Hubble Snaps the Best Close-ups Yet of Speedy Visitor from the Stars

When astronomers see something in the universe that at first glance seems like one-of-a-kind, it's bound to stir up a lot of excitement and attention. Enter comet 2I/Borisov. This mysterious visitor from the depths of space is the first identified comet to arrive here from another star. We don't know from where or when the comet started heading toward our Sun, but it won't hang around for long. The Sun's gravity is slightly deflecting its trajectory, but can't capture it because of the shape of its orbit and high velocity of about 100,000 miles per hour.

Above: These two images, taken by NASA's Hubble Space Telescope, capture comet 2I/Borisov streaking though our solar system and on its way back to interstellar space. It is only the second interstellar object known to have passed through the solar system.

Telescopes around the world have been watching the fleeting visitor. Hubble has provided the sharpest views as the comet skirts by our Sun. Since October the space telescope has been following the comet like a sports photographer following horses speeding around a racetrack. Hubble revealed that the heart of the comet, a loose agglomeration of ices and dust particles, is likely no more than about 3,200 feet across, about the length of nine football fields. Though comet Borisov is the first of its kind, no doubt there are many other comet vagabonds out there, plying the space between stars. Astronomers will eagerly be on the lookout for the next mysterious visitor from far beyond.

These two images, taken by NASA's Hubble Space Telescope, capture comet 2I/Borisov streaking though our solar system and on its way back to interstellar space. It is only the second interstellar object known to have passed through the solar system.

"Hubble gives us the best upper limit of the size of comet Borisov's nucleus, which is the really important part of the comet," said David Jewitt, a UCLA professor of planetary science and astronomy, whose team has captured the best and sharpest look at this first confirmed interstellar comet. "Surprisingly, our Hubble images show that its nucleus is more than 15 times smaller than earlier investigations suggested it might be. Our Hubble images show that the radius is smaller than half-a-kilometer. Knowing the size is potentially useful for beginning to estimate how common such objects may be in the solar system and our galaxy. Borisov is the first known interstellar comet, and we would like to learn how many others there are."

Crimean amateur astronomer Gennady Borisov discovered the comet on August 30, 2019 and reported the position measurements to the International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts. The Center for Near-Earth Object Studies at the Jet Propulsion Laboratory, working with the Minor Planet Center, computed an orbit for the comet which shows that it came from elsewhere in our Milky Way galaxy, point of origin unknown.

Nevertheless, observations by numerous telescopes show that the comet's chemical composition is similar to the comets found inside our solar system, providing evidence that comets also form around other stars. By the middle of 2020 the comet will have already zoomed past Jupiter's distance of 500 million miles on its way back into the frozen abyss of interstellar space.

• [left] November 16, 2019 photo

  The comet appears in front of a distant background spiral galaxy (2MASX J10500165-0152029). The galaxy's bright central core is smeared in the image because Hubble was tracking the comet. Comet Borisov was approximately 203 million miles from Earth in this exposure. Its tail of ejected dust streaks off to the upper right. The comet has been artificially colored blue to discriminate fine detail in the halo of dust, or coma, surrounding the central nucleus. It also helps to visually separate the comet from the background galaxy.

• [right] December 9, 2019 photo

  Hubble revisited the comet shortly after its closest approach to the Sun where it received maximum heating after spending most of its life in frigid interstellar space. The comet also reached a breathtaking maximum speed of about 100,000 miles per hour. Comet Borisov is 185 million miles from Earth in this photo, near the inner edge of the asteroid belt but below it. The nucleus, an agglomeration of ices and dust, is still too small to be resolved. The bright central portion is a coma made up of dust leaving the surface. The comet will make its closest approach to Earth in late December at a distance of 180 million miles.

posted 06-04-2020 08:30 AM               

The idea is the conclusion reached by Darryl Seligman of the University of Chicago and Gregory Laughlin of Yale University in a paper to be published in the Astrophysical Journal Letters (a preprint is available at arXiv.org). They examined existing data on an object called 'Oumuamua, which became the first interstellar object discovered in our solar system in October 2017. Since then there has been some debate over whether it was a comet or asteroid; no one is quite sure. Seligman and Laughlin, however, say the object was neither. "We're proposing that 'Oumuamua was composed of molecular hydrogen ice," Seligman says. "Basically, it was a hydrogen iceberg."

posted 08-18-2020 10:27 AM               

Harvard and Smithsonian Center for Astrophysics release

Scientists Determine 'Oumuamua Isn't Made From Molecular Hydrogen Ice After All

The debate over the origins and molecular structure of 'Oumuamua continued today with an announcement in The Astrophysical Journal Letters that despite earlier promising claims, the interstellar object is not made of molecular hydrogen ice after all.

The earlier study, published by Seligman & Laughlin in 2020 — after observations by the Spitzer Space Telescope set tight limits on the outgassing of carbon-based molecules — suggested that if 'Oumuamua were a hydrogen iceberg, then the pure hydrogen gas that gives it its rocket-like push would have escaped detection. But scientists at the Center for Astrophysics | Harvard & Smithsonian (CfA) and the Korea Astronomy and Space Science Institute (KASI) were curious whether a hydrogen-based object could actually have made the journey from interstellar space to our solar system.

"The proposal by Seligman and Laughlin appeared promising because it might explain the extreme elongated shape of 'Oumuamua as well as the non-gravitational acceleration. However, their theory is based on an assumption that H2 ice could form in dense molecular clouds. If this is true, H2 ice objects could be abundant in the universe, and thus would have far-reaching implications. H2 ice was also proposed to explain dark matter, a mystery of modern astrophysics," said Dr. Thiem Hoang, senior researcher in the theoretical astrophysics group at KASI and lead author on the paper. "We wanted to not only test the assumptions in the theory but also the dark matter proposition." Dr. Avi Loeb, Frank B. Baird Professor of Science at Harvard and co-author on the paper, added, "We were suspicious that hydrogen icebergs could not survive the journey — which is likely to take hundreds of millions of years — because they evaporate too quickly, and as to whether they could form in molecular clouds."

Traveling at a blistering speed of 196,000mph in 2017, 'Oumuamua was first classified as an asteroid, and when it later sped up, was found to have properties more akin to comets. But the 0.2km radius interstellar object didn't fit that category, either, and its point of origin has remained a mystery. Researchers focused on the giant molecular cloud (GMC) W51 — one of the closest GMCs to Earth at just 17,000 light years away — as a potential point of origin for 'Oumuamua, but hypothesize that it simply could not have made the journey intact. "The most likely place to make hydrogen icebergs is in the densest environments of the interstellar medium. These are giant molecular clouds," said Loeb, confirming that these environments are both too far away and are not conducive to the development of hydrogen icebergs.

An accepted astrophysical origin for solid objects is growth by sticky collisions of dust, but in the case of a hydrogen iceberg, this theory could not hold together. "An accepted route to form a km-sized object is first to form grains of micron-size, then such grains grow by sticky collisions," said Hoang. "However, in regions with high gas density, collisional heating by gas collisions can rapidly sublimate the hydrogen mantle on the grains, preventing them from growing further."

Although the study explored destruction of H2 ice by multiple mechanisms including interstellar radiation, cosmic rays, and interstellar gas, sublimation due to heating by starlight has the most destructive effect, and according to Loeb, "Thermal sublimation by collisional heating in GMCs could destroy molecular hydrogen icebergs of 'Oumuamua-size before their escape into the interstellar medium." This conclusion precludes the theory that 'Oumuamua journeyed to our solar system from a GMC, and further precludes the proposition of primordial snowballs as dark matter. Evaporative cooling in these situations does not reduce the role of thermal sublimation by starlight in the destruction of H2 ice objects.

'Oumuamua first gained notoriety in 2017 when it was discovered screaming through space by observers at Haleakalā Observatory, and has since been the subject of ongoing studies. "This object is mysterious and difficult to understand because it exhibits peculiar properties we have never seen from comets and asteroids in our solar system," said Hoang.

While the nature of the interstellar traveler is currently an unsolved mystery, Loeb suggests it won't remain so for much longer, especially if it's not alone. "If 'Oumuamua is a member of a population of similar objects on random trajectories, then the Vera C. Rubin Observatory (VRO), which is scheduled to have its first light next year, should detect roughly one 'Oumuamua-like object per month. We will all wait with anticipation to see what it will find."

posted 04-12-2022 09:20 PM               

In 2014, a half-ton, couch-sized meteor entered the atmosphere above Papua New Guinea, brightening the night sky. It may sound like a threat, but once a meteor such as this enters our atmosphere it generally burns up. This space rock caused a loud flash and bang captured on observatory cameras, but there are 25 million meteor entries of various sizes around Earth every day, so no one gave it a second thought. At first.

But Avi Loeb, a Harvard University astrophysicist, and his student Amir Siraj saw something else in that remote bolide explosion: Five years after the meteor appeared in 2019, they looked at the data on it from NASA JPL's Center for Near Earth Object Studies. They saw something fast. They saw something powerful. They saw, in short, something from outside our Solar System.

"It appeared to be a head-on collision," Loeb tells Inverse.

Loeb and Siraj made their discovery while on the hunt for fast fireballs, the kind of meteor that strikes our upper atmosphere at such a velocity that they could have hurtled in from interstellar space.

But nobody else saw what they did, and their paper on the object was rejected by the Astrophysical Journal Letters. Now, three years after their discovery, a letter from the United State Space Command to NASA chief scientist Thomas Zurbuchen relayed that Space Force had looked into their results: Loeb and Siraj's measurements were seemingly correct.

posted 04-15-2022 08:40 AM               

Many scientists, including those at NASA, say that the military still has not released enough data to confirm the interstellar origins of the space rock, and a spokeswoman said Space Command would defer to other authorities on the question. ...

NASA said in a public statement this month that "the short duration of collected data, less than five seconds, makes it difficult to definitively determine if the object's origin was indeed interstellar."

"Quite frankly, we can't confirm that it's interstellar," NASA's planetary defense officer, Lindley Johnson, said in an interview. "Although it is of high velocity, a velocity that could be potentially interstellar, it is next to impossible to confirm that it's interstellar without accompanying data — from a longer data span or data from other sources, which doesn't exist in this case."

Dr. Loeb and Mr. Siraj disagreed. "Five seconds is plenty of time," Dr. Loeb said. "It's not the duration that matters, it's the quality of the data that was assembled that matters. During five seconds you can do a lot, in terms of instrumentation and measurement."

posted 04-27-2022 10:00 AM               

Loeb sees the opportunity to locate fragments of the 2014 meteor as a unique one: An object has landed on Earth and is now within grasp for far less time, money, and effort than what it would require to send a vessel into space to collect samples of interstellar material.

His plan is to spend a week or so digging around for remnants of the meteor, which likely split into many tiny pieces and has dispersed over around six miles in the Pacific Ocean, from a ship. Though he's still figuring out exactly what a magnetized deep sea retrieval device would look like, Loeb is in early conversations with funders and a ship operator. He suspects the final design will need to be slightly different from existing devices designed to locate objects from within our solar system, but those offer a starting point.

"All we can imagine are things that we've seen before," Loeb said. "Usually what you get from meteors like that, that end up impacting the ocean, is a lot of fragments the size of the head of a needle. They're really small, a millimeter or less, and there's lots of them and you can scoop them up because they're magnetized. So if you use a magnet and sort of go over the ocean surface, you can collect them."

posted 09-25-2022 03:34 PM               

The first interstellar meteor, CNEOS 2014-01-08 (IM1), that Amir and I discovered in 2019, was confirmed at the 99.999% confidence level by a letter from the US Space Command to NASA. The second interstellar meteor we just discovered, CNEOS 2017-03-09 (IM2), was ten times more massive and roughly a meter in size. It was moving at a speed of 40 (compared to 60 for IM1) kilometers per second relative to the Local Standard of Rest, the local frame of reference of the Milky Way that averages over the motions of all the stars in the vicinity of the Sun.

posted 09-29-2022 12:08 PM               

Maybe, just maybe, those superconducting minerals that came from space are also artificial, B.P. Embaid, a physicist at Central University of Venezuela, hypothesized in a study — not yet peer-reviewed — that appeared online on Sept. 13.

And if that's the case, the minerals could be evidence of extraterrestrial technology—"technosignatures," as scientists like to say. "It is important to be open-minded and even provocative to consider the following question: are these meteoritic minerals samples of extraterrestrial technosignatures?" Embaid wrote.

posted 03-23-2023 08:33 PM               

"We can explain a lot of the strange behavior," says Jennifer Bergner, a chemist at the University of California, Berkeley, who led the work, published today in Nature.

The study is "the most convincing model so far" for 'Oumuamua, says Marco Micheli, an astronomer at the European Space Agency in Italy who was not involved with the work. The alien visitor, he says, was actually not so different from Solar System comets.

NASA's Hubble and Spitzer telescopes found that 'Oumuamua had an oddly elongated, cigarlike shape between 100 meters and 400 meters long. It also sped up slightly as it left the Solar System. That can happen with comets as they recoil from the material they emit, explains Micheli, who led the initial work on 'Oumuamua's acceleration in 2018. 'Oumuamua, however, showed no such ejecta. There was no visible coma of dust and gas around the object, nor any tail, both of which would be expected from a comet.

Bergner and her colleague Darryl Seligman, an astronomer at Cornell University, think they can now explain what happened. Their modeling shows 'Oumuamua could have begun life as a regular water-rich comet around a nearby star, before being ejected. They found that high-energy cosmic rays that pervade the Galaxy, emitted by supernovae and other energetic events, could have turned up to 30% of the comet's water ice into hydrogen, which could have become trapped in 'Oumuamua's ice as it journeyed through interstellar space.

As 'Oumuamua approached the heat of the Sun, it would have released the trapped hydrogen, giving the object its observed speed boost. But molecular hydrogen, being much less massive than the carbon monoxide or carbon dioxide ejected in typical comets, would not have had the momentum to pull much dust with it, explaining the lack of a coma or tail. "We don't need to invoke anything superexotic to explain this behavior," Bergner says.