Astronomers found out that there are seven times more massive comets that prevail in our solar system than previously predicted.
According to NASA, it's difficult to analyse long-period comets which are not likely to approach the Sun in the lifetime of a person. Such space rocks spend most of their time far away from the region of our solar system.
"In fact, those that travel inward from the Oort Cloud -- a group of icy bodies beginning roughly 186 billion miles (300 billion kilometres) away from the Sun -- can have periods of thousands or even millions of years," as per a NASA statement.
NASA's WISE spacecraft revealed the new insights about these distant space rocks after examining the entire sky at infrared wavelengths. It was found that around seven times more long-period comets exist in the solar system; these distant comets measure around a kilometre (0.6 miles).
They also discovered that the long-period comets are twice the size of short-period comets aka the "Jupiter family comets", the orbits of these comets are shaped by Jupiter's gravity and they got an orbit period of less than 20 years.
The researchers also observed that in eight months, three to five times as many long-period comets passed by the Sun than it had been predicted.
"The number of comets speaks to the amount of material left over from the solar system's formation," said James Bauer, lead author of the study and now a research professor at the University of Maryland, College Park.
"We now know that there are more relatively large chunks of ancient material coming from the Oort Cloud than we thought," according to a statement.
The Oort cloud is found to be very distant when observed by current telescopes. It is believed to be a spherical distribution of small icy bodies which are situated at the outermost edge of the solar system. The density of the comets prevailing within the Oort Cloud is low which lessens the chances of comet collisions.
The long-period comets spotted by the Wide-field Infrared Survey Explorer (WISE), likely got kicked out of the Oort Clouds millions of years ago. These observations were made during the primary mission of the spacecraft before it was renamed NEOWISE and reactivated to target NEOs (Near-Earth objects).
"Our study is a rare look at objects perturbed out of the Oort Cloud," said Amy Mainzer, study co-author based at NASA's Jet Propulsion Laboratory, Pasadena, California, and principal investigator of the NEOWISE mission. "They are the most pristine examples of what the solar system was like when it formed."