About a month ago, a mysterious object was spotted hurtling through the solar system, and it was later confirmed to be an interstellar visitor headed for the Sun. Since then, several telescopes have turned their attention to the wandering object, but it turns out that the brand-new Vera K. Rubin Observatory was the first to see 3I/ATLAS.
In an act of cosmic serendipity, astronomers pointed the Rubin Observatory at the patch of sky where the interstellar object appeared during its commissioning. Images taken by the observatory, located on top of a mountain in the Chilean Andes, subsequently showed the comet in all its glory. Rubin’s observations of Comet 3I/ATLAS were recorded on June 21, about 10 days before its official discovery, according to a recent article available on the arXiv preprint site.
Rubin Observatory, operated by the National Science Foundation (NSF) and the Department of Energy (DOE), boasts the largest digital camera ever built for astronomy. Its 3.2-gigapixel, car-sized camera is designed to capture ultra-high-definition images and video of space. The observatory released its first images to the public on June 23, observing millions of galaxies and stars in the Milky Way over a span of just 10 hours. The images were not only beautiful – they also revealed supernovae and distant galaxies that could help astronomers study the expansion of the universe.
Not surprisingly, thanks to its revolutionary precision, the Rubin Observatory detected the newly discovered comet before any other telescope. 3I/ATLAS was first spotted in the data collected by the Asteroid Terrestrial-impact System (ATLAS) between June 25 and 29, and then again on July 1. On July 2, it was also seen by the Deep Random Survey remote telescope in Rio Hurtado, Chile. The Minor Planet Center of the International Astronomical Union confirmed that this comet came from outside our solar system on July 2, which was the third discovery of an interstellar object.
Since then, astronomers have been rushing to collect as much data as possible about the mysterious object. The Gemini North telescope in Maunakea, Hawaii, recently took an up-close photo of 3I/ATLAS, capturing the comet in minute detail. Initial observations of 3I/ATLAS indicate that it is the oldest comet ever found, about 2 billion years older than our solar system. Compared to the two previously discovered interstellar objects, Oumuamua and Comet 2I/Borisov, 3I/ATLAS is not only older, but also faster. A recent study, which has yet to be peer-reviewed, found that 3I/ATLAS has a hyperbolic velocity of about 37 miles per second (60 kilometers per second).
Rubin’s early observations of 3I/ATLAS are important because they are the very first images of the comet obtained by a high-precision telescope. The new paper contains 49 images, although some were excluded because they were taken during Rubin’s alignment sequence and were out of focus. Nineteen of the images were taken during targeted operations and confirm that 3I/ATLAS does indeed behave like a comet, with a cloud of gas and dust surrounding its icy nucleus, the paper says.
Just as it was the first to spot the comet, Rubin will also be the first to lose sight of it. On August 22, 3I/ATLAS will move out of the area of the sky that the observatory is currently observing. Until then, the astronomers behind this article will keep an eye on the interstellar visitor in Rubin’s images.
