The world witnessed our first interstellar visitor on October 19. Many others may have come before it, but it wasn’t until recently that we were finally able to detect one for the very first time, thanks to our powerful telescopes.
A month after the mysterious traveler was spotted by the Pan-STARRS-1 telescope at the Haleakala Observatory in Hawaii, new exciting details came to light about the interstellar object, which has now been confirmed as an asteroid and has received a proper name worthy of its uniqueness.
Formerly known as A/2017 U1, the interstellar traveler has finally been given the more creative moniker of ‘Oumuamua; a Hawaiian word that translates as “a messenger from afar arriving first,” the International Astronomical Union (IAU) announced on November 14.
According to the IAU, this new name “appropriately reflects the nature of the object and its discovery.” At the same time, ‘Oumuamua has also been given the official (more technical) designation of 1I/2017 U1, in which the “I” stands for “interstellar.”
As a matter of fact, this designation scheme (inspired by the standard ones used for comets and asteroids, which sport a “C” or “A,” respectively) was specially created for this unusual, one-of-a-kind object. The IAU news release shows that 1I/2017 U1, now classified as an “interstellar asteroid,” is “a prototype of a new class of objects” and has been deemed so due to its hyperbolic trajectory leading it out of our solar system “and record-breakingly high eccentricity.”
“It’s a really rare object,” says Ralf Kotulla, an astronomer at the University of Wisconsin–Madison, and leader of the team that captured some of the first images of 1I/2017 U1.
Initially discovered by Rob Weryk, a postdoctoral researcher at the University of Hawaii’s Institute for Astronomy, the interstellar asteroid ‘Oumuamua was later observed by Kotulla’s team, which gained further insight into the object’s shape.
Aided by colleagues from UCLA and the National Optical Astronomy Observatory, Kotulla’s team used the 11.5-foot (3.5 meters) WIYN Telescope on Kitt Peak in Arizona to take some snapshots of ‘Oumuamua. When it was first discovered, our first interstellar visitor was originally thought to be an ancient comet. However, these first images revealed no sign of a coma (the streak of dust and gas observed as a comet’s tail). Instead, they confirmed 1I/2017 U1 as an irregularly shaped asteroid.
The observations made with the WIYN Telescope occurred almost two weeks after the interstellar asteroid passed closest to Earth on October 14, when ‘Oumuamu came within 60 lunar distances from our planet. These observations, detailed in a news release issued by the University of Wisconsin–Madison, uncovered 1I/2017 U1 is a small, elongated asteroid with a cigar-like shape that moves at very fast speed and displays a reddish tinge in its color, as well as variations in its brightness.
Since ‘Oumuamu’s trajectory will soon take it out of our solar system, other astronomers rushed to study it and glean more information about its characteristics. Such is the case of Karen Meech, a researcher from the same institute as the man who discovered the asteroid.
Meech just published a paper describing the shape and color of the interstellar asteroid. Her team employed the European Southern Observatory’s (ESO) Very Large Telescope (VLT) in Chile to take a closer look at ‘Oumuamua. Their study, featured yesterday (November 20) in the journal Nature, corroborates the observations made earlier by Kotulla’s team.
The VLT’s FORS instrument enabled Meech and her team to make very precise spectroscopic measurements of the asteroid’s brightness and color. Their findings, also presented in an ESO news release, show the interstellar asteroid’s brightness varies by a factor of 10 as ‘Oumuamua spins on its axis every 7.3 hours.
“This unusually large variation in brightness means that the object is highly elongated: about 10 times as long as it is wide, with a complex, convoluted shape,” explained Meech.
The VLT observations also uncovered that ‘Oumuamua sports a dark red color, similar to that of objects found in the Kuiper Belt, Meech added. According to the astronomers, this reddish hue could be the result of cosmic irradiation spanning millions of years. Additionally, her team was able to ascertain that the interstellar asteroid “is completely inert, without the faintest hint of dust around it.”
National Geographic reports Meech described ‘Oumuamua as being “extraordinarily elongated,” which she points out is a highly uncommon feature.
“We don’t see anything like that in our solar system.”
All these characteristics suggest the interstellar asteroid is relatively dense and most likely rocky, with the possibility of some metal content. The researchers also believe ‘Oumuamua lacks significant amounts of water or ice.
Our interstellar visitor is now 124 million miles from Earth, which is the distance between Mars and Jupiter, CNN notes. ‘Oumuamua’s path has taken it beyond the red planet’s orbit and will lead it past Jupiter in May. From there, the interstellar asteroid is bound for Saturn’s orbit and will zoom past it in January 2019, leaving our solar system for good.
[Featured Image by Vadim Sadovski/Shutterstock]