Oumuamua part 2: Astronomers have likely discovered a second interstellar object, called Borisov
A newly discovered object - a comet that seems to be from another star and is speeding through our solar system - has sparked massive excitement and interest among the scientific community as it could mark the second time that astronomers have spotted an interstellar object.
Dubbed as C/2019 Q4 (Borisov), the object was first detected on August 30 by Gennady Borisov, an amateur astronomer at the MARGO observatory in Nauchnij, Crimea. While there has been no official confirmation so far that C/2019 Q4 is an interstellar object, if it is confirmed as one, it would only be the second such object spotted.
The first interstellar object to pass through the solar system - Oumuamua - was detected and confirmed in October 2017. Recently, a team of astronomers confirmed that the cigar-shaped object is of "natural origin." Back then scientists had stated that it is possible that one or two such interstellar objects will be discovered in the next four to five years. After that, scientists anticipate that future large surveys like the Large Synoptic Survey Telescope (LSST) - which is scheduled to be operational in 2022 - will find approximately one per year.
Observations on C/2019 Q4, 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. Currently on an inbound trajectory, comet C/2019 Q4 is heading toward the inner solar system.
Astronomers will be able to observe C/2019 Q4 for at least a year, which will enable them to understand and record its composition, how different it is from comets in our solar system, its physical properties such as size, and rotation. It will also allow them to better identify its trajectory. Scientists will be able to observe it with professional telescopes for the next few months. According to Davide Farnocchia of NASA's Center for Near-Earth Object Studies at JPL, C/2019 Q4 will peak in brightness in mid-December, and astronomer will be able to see it with moderate-size telescopes until April 2020. After that, says Farnocchia, it will only be observable with larger professional telescopes through October 2020.
A formal announcement of the discovery was made by the Minor Planet Center (MPC) at Harvard University. "Based on the available observations, the orbit solution for this object has converged to the hyperbolic elements shown below, which would indicate an interstellar origin. Further observations are clearly very desirable, as all currently-available observations have been obtained at small solar elongations and low elevations," says the statement issued by MPC. It adds, "Absent an unexpected fading or disintegration, this object should be observable for at least a year."
In the days that followed the first detection, other astronomers made similar observations. "A newly discovered comet has excited the astronomical community this week because it appears to have originated from outside the solar system," says a NASA statement.
According to scientists, the object is moving very fast - its current velocity is about 93,000 mph or 150,000 kph - which is a telltale sign that it is from interstellar space. "The comet's current velocity is high, which is well above the typical velocities of objects orbiting the sun at that distance. 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," says Farnocchia.
According to NASA, the object was "established as being cometary due to its fuzzy appearance," which suggests that C/2019 Q4 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 the sky not usually scanned by the large ground-based asteroid surveys or NASA's asteroid-hunting NEOWISE spacecraft," says NASA.
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. Farnocchia worked with astronomers and the European Space Agency's Near-Earth Object Coordination Center in Frascati, Italy, to record 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," says the NASA statement.
According to NASA, the new comet 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). The comet is currently 260 million miles or 420 million kilometers from the sun and will reach its closest point, or perihelion, on December 8, 2019, at a distance of about 190 million miles. "It is expected to pass through the ecliptic plane (where Earth and other planets orbit the sun) "from above at roughly a 40-degree angle," says the statement.