Recently, astronomers have observed a fascinating asteroid, which whizzed through our inner solar system on a vertical route from interstellar space. The asteroid, which has been named Oumuamua, is the first object that has been officially confirmed to be from another star.
Now, new data has revealed that the interstellar intruder is a rocky object, shaped like a cigar, and has a reddish hue. According to a NASA report, the Oumuamua asteroid is around one-quarter mile in length. Experts predict that the object is, maybe, 10 times longer than its width. That aspect ratio of this first interstellar asteroid is larger than that of all the asteroids or comets that have been spotted in our solar system to date. Scientists think that this will give them new information as to how other solar systems in the universe are created.
As per the new findings and analyses published in scientific journal Nature, this extraordinary asteroid had been traveling through the Milky Way since hundreds of millions of years before it got a chance to enter 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. This history-making discovery is opening a new window to study formation of solar systems beyond our own," said the associate administrator for NASA's Science Mission Directorate in Washington Thomas Zurbuchen.
As it was important to view the asteroid with the help of the ground-based telescopes to extract the best information immediately after its discovery, other telescopes were called into action to observe the object's orbit, brightness and color. These telescopes included ESO's Very Large Telescope in Chile and strong telescopes from other observatories around the world.
A team of astronomers, which was led by Karen Meech from the Institute for Astronomy in Hawaii, combined the images of the asteroid that came from the ESO telescope's FORS instrument and applied four filters on them along with the other images from other big telescopes. As a result, the astronomers found out that the object span on its axis every 7.3 hours and also changed its brightness by a factor of ten.
The experts concluded that no asteroid or comet's brightness differs so much in our solar system.
"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 indicate that Oumuamua is dense, consists of rock and, most probably, metals too but it most certainly doesn't carry water or ice. The experts also concluded that its blemished surface is as an effect of irradiation that ensued from cosmic rays since millions of years.
Some of the large ground-based telescopes, including NASA's Hubble and Spitzer, are still tracking the asteroid, although, it's quickly fading, as it is going further away from our planet. "As of November 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," stated NASA.
The observations will continue until the object becomes undetectable to the telescopes, which is supposed to be sometime around mid-December, expects the space agency.
This remarkable object was first discovered on October 19 by the University of Hawaii's Pan-STARRS1 telescope, which is funded by NASA's Near-Earth Object Observations (NEOO) Program. The aim of this program is to find and track down the asteroids and comets that come around Earth's neighborhood.
"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," said NASA Planetary Defense Officer Lindley Johnson.
According to the first round of orbital calculations, this object approached from the estimated direction of the bright star Vega, which is located at the Lyra constellation in the northern sky. However, it took the interstellar object to finally reach our solar system so long, even when it has a speed of about 59,000 miles per hour, because Vega was not near that position when Oumuamua had visited the spot around 300,000 years ago.
Astronomers estimate that one interstellar asteroid, like Oumuamua, passes through our inner solar system at least once per year; however, they do not get spotted by Earth's telescopes because they are too faint.
"What a fascinating discovery this is! It's a strange visitor from a faraway star system, shaped like nothing we've ever seen in our own solar system neighborhood," said very excited Paul Chodas, manager of the Center for Near-Earth Object Studies at NASA's Jet Propulsion Laboratory, Pasadena, California.