from the just-passing-through dept.
Astronomer Rob Weryk has identified what appears to be the first interstellar object to enter (and soon exit) the solar system. The object, provisionally designated A/2017 U1, is estimated to be 400 meters in diameter:
A/2017 U1 was discovered Oct. 19 by the University of Hawaii's Pan-STARRS 1 telescope on Haleakala, Hawaii, during the course of its nightly search for near-Earth objects for NASA. Rob Weryk, a postdoctoral researcher at the University of Hawaii Institute for Astronomy (IfA), was first to identify the moving object and submit it to the Minor Planet Center. Weryk subsequently searched the Pan-STARRS image archive and found it also was in images taken the previous night, but was not initially identified by the moving object processing.
[...] "This is the most extreme orbit I have ever seen," said Davide Farnocchia, a scientist at NASA's Center for Near-Earth Object Studies (CNEOS) at the agency's Jet Propulsion Laboratory in Pasadena, California. "It is going extremely fast and on such a trajectory that we can say with confidence that this object is on its way out of the solar system and not coming back."
The CNEOS team plotted the object's current trajectory and even looked into its future. A/2017 U1 came from the direction of the constellation Lyra, cruising through interstellar space at a brisk clip of 15.8 miles (25.5 kilometers) per second.
The object approached our solar system from almost directly "above" the ecliptic, the approximate plane in space where the planets and most asteroids orbit the Sun, so it did not have any close encounters with the eight major planets during its plunge toward the Sun. On Sept. 2, the small body crossed under the ecliptic plane just inside of Mercury's orbit and then made its closest approach to the Sun on Sept. 9. Pulled by the Sun's gravity, the object made a hairpin turn under our solar system, passing under Earth's orbit on Oct. 14 at a distance of about 15 million miles (24 million kilometers) -- about 60 times the distance to the Moon. It has now shot back up above the plane of the planets and, travelling at 27 miles per second (44 kilometers per second) with respect to the Sun, the object is speeding toward the constellation Pegasus.
"We have long suspected that these objects should exist, because during the process of planet formation a lot of material should be ejected from planetary systems. What's most surprising is that we've never seen interstellar objects pass through before," said Karen Meech, an astronomer at the IfA specializing in small bodies and their connection to solar system formation.
Here is a direct link to an animation of the object's passage.
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.
[...] Scientists who have made observations of 'Oumuamua, say that despite its exotic origins, the asteroid is familiar in appearance. In a paper submitted to Astrophysical Journal Letters, they argue that its size, rotation, and reddish colour are similar to those of asteroids in our Solar System. Measuring about 180m by 30m, it resembles a chunky cigar.
"The most remarkable thing about ['Oumuamua'] is that, except for its shape, how familiar and physically unremarkable it is," said co-author Jayadev Rajagopal from the US National Optical Astronomy Observatory (NOAO).
The interstellar asteroid 'Oumuamua's likely movements have been tracked based on the relative positions of nearby stars. Observations of 'Oumuamua indicate that it has only been subjected to interstellar conditions (cosmic rays, gas, dust) for hundreds of millions of years rather than billions. There are likely to be around 46 million such interstellar objects entering the solar system every year, most of which are too far away to be seen with current telescopes, and are quickly ejected:
[My (Fabo Feng)] latest study gives us a glimpse of exactly where 'Oumuamua may have come from. Reconstructing the object's motion, my research suggests it probably came from the nearby "Pleiades moving group" of young stars, also known as the "Local Association". It was likely ejected from its home solar system and sent out to travel interstellar space.
Based on 'Oumuamua's trajectory, I simulated how it has probably travelled through the galaxy and compared this to the motions of nearby stars. I found the object passed 109 stars within a distance of 16 light years. It went by five of these stars from in the Local Association (a group of young stars likely to have formed together), at a very slow speed relative to their movement.
It's likely that when 'Oumuamua was first ejected into space, it was travelling at just enough speed to break away from the gravity of its planet or star of origin, rather than at a much faster speed that would require even more energy. This means we'd expect the object to move relatively slowly at the start of its interstellar journey, and so its slow encounters with these five stars suggests it was ejected from one of the group.
We should capture as many interstellar asteroids as possible and smash them together to create a new dwarf planet near the Earth.
Previously: Possible Interstellar Asteroid/Comet Enters Solar System
Interstellar Asteroid Named: Oumuamua
ESO Observations Show First Interstellar Asteroid is Like Nothing Seen Before
Breakthrough Listen to Observe Interstellar Asteroid 'Oumuamua for Radio Emissions (none were found)
The team's efforts will begin on Wednesday, with astronomers observing the asteroid, which is currently speeding away from our Solar System, across four different radio frequency bands. The first set of observations is due to last for 10 hours.
[...] Mr Milner's Breakthrough Listen programme released a statement which read: "Researchers working on long-distance space transportation have previously suggested that a cigar or needle shape is the most likely architecture for an interstellar spacecraft, since this would minimise friction and damage from interstellar gas and dust."
Andrew Siemion, director of the Berkeley SETI Research Center, who is part of the initiative, said: "'Oumuamua's presence within our Solar System affords Breakthrough Listen an opportunity to reach unprecedented sensitivities to possible artificial transmitters and demonstrate our ability to track nearby, fast-moving objects." He added: "Whether this object turns out to be artificial or natural, it's a great target for Listen."