This is the largest known ice comet nucleus, as measured by NASA's Hubble Space Telescope. It is larger than the state of Rhode Island, with a circumference estimated at 80 miles. Most known comets have nuclei that are less than half the size of this one. It is expected to have a mass of 500 trillion tonnes, a hundred thousand times that of a typical comet found closer to the Sun.
A massive comet, more than twice the breadth of Rhode Island at 80 miles wide, is speeding toward us from the boundary of the solar system at 22,000 miles per hour. Fortunately, it will never come closer to the sun than 1 billion miles, which is slightly farther away from Earth than Saturn; that will be in 2031..
Previously, the comet with the "biggest nucleus" was C/2002 VQ94, which was discovered in 2002 and was believed to be 60 miles (96 km) across.
This new gigantic comet was discovered in 2010. Several years later, astronomers Pedro Bernardineli and Gary Bernstein discovered the object in archival data collected by the Dark Energy Survey at Chile's Cerro Tololo Inter-American Observatory. Since its discovery, the object has been researched with a wide range of instruments, including both ground-based observatories and space-based telescopes such as Hubble.