There have been several new developments regarding C/2014 UN271 – also known as the largest comet that’s ever been detected in modern times. The comet, which was discovered by Pedro Bernardinelli and Gary Bernstein, is believed to have come from about 40,000 Astronomical Units (AU) away in the Oort Cloud (one AU is the distance of Earth from the sun).
The first bit of news is that the comet finally grew a tail. When it was at a distance of around 29 AU away, it wasn’t showing the normal characteristic of a comet, such as having a tail. However, when it was at 19 AU away, astronomers at the Las Cumbres Observatory in South Africa took some images of C/2014 UN271 and noticed a fuzzy border which was created from vaporized material from the sunlight which meant that it was definitely a comet. Furthermore, it also started forming a tail. (A picture of C/2014 UN271 with its fuzzy border taken by the Las Cumbres Observatory can be seen here.)
The second piece of news was that C/2014 UN271 became brighter for a short amount of time. According to data collected by the Las Cumbres Observatory’s 1-m telescope, the comet had faded, but later showed a burst of brightness. The brightness occurred on September 11th when it was located approximately 19.89 AU from the sun.
The last bit of news is regarding its size. Initial estimates claimed that C/2014 UN271 had a diameter that was anywhere between 62 and 124 miles (between 100 and 200 kilometers). This was very significant and jaw-dropping because that would mean that it was about ten times wider than a normal comet. Astronomers revealed those estimates based on the amount of sunlight that was reflecting off of its icy body. Now, however, new analysis of the comet has narrowed down its estimated size to being 93 miles in diameter (150 kilometers).
While these new facts regarding C/2014 UN271 are very interesting, it is still very far from us at a distance of about 19.37 AU away from Earth. It has traveled about 7 AU in the last year but it will still be a while before it makes its closest approach to us which has been predicted to happen on April 5, 2031 when it will be at a distance of 10.11 AU away. To put this into better perspective, when it makes its closest approach in 2031, it will be about the same distance that Saturn is to the sun.
In the next ten years, scientists should gather even more amazing data and facts about the largest comet ever detected.