The recently discovered Comet Nishimura, C/2023 P1, has been generating buzz among the public. While its trajectory suggests a close approach to the Sun and the possibility of being visible to the naked eye, experts believe that it is unlikely to provide a spectacular sky display.
Comets are one of the most awe-inspiring objects in the Solar System, and the prospect of witnessing a great comet in our skies is always exciting. The current comet capturing attention is C/2023 P1 (Nishimura), which was discovered by Japanese astronomer Hideo Nishimura on August 12. Astronomers were able to determine its path by analyzing pre-discovery images dating back to January.
It was soon realized that Nishimura would come closer to the Sun than the orbit of Mercury this month. At the time of its discovery, the comet showed enough brightness to potentially be visible to the naked eye. However, its path will keep it close to the Sun in the sky as observed from Earth. This means that even though it is bright enough to be seen in dark skies, it will likely be hugging the horizon just after sunset, nearly lost in the Sun’s glow.
Despite its limited visibility, astronomers worldwide are still excited about studying and observing Nishimura. As science writer and astronomer David H. Levy once said, “Comets are like cats: they have tails, and they do precisely what they want.” There is always a chance that Nishimura may brighten unexpectedly, providing a special sight in the next couple of weeks. If not, there is still hope for future comet sightings.
When comets are far from the Sun, they resemble dirty snowballs, composed of ice, dust, and rock. As a comet approaches the Sun, the surface heats up, causing the icy layers to turn into gas and erupt outward. This gas, along with dust and debris, forms a glowing cloud around the nucleus called a coma. The solar wind then blows the gas and dust away from the Sun, creating the iconic tail of a comet. The brightness of a comet is determined by the size of its nucleus, its distance from the Sun, and its distance from Earth.
Based on what we know about Nishimura, it is unlikely to be a large comet. Additionally, it is not particularly close to Earth. However, it is expected to be very active around perihelion, its closest point to the Sun. Although it would have been an impressive sight in a dark night sky, Nishimura’s position relative to the Sun and Earth makes it challenging to observe.
There is a short window to catch a glimpse of Nishimura from Australia, where it will peek above the western horizon after sunset. The best chance to see it comes in the week of September 20 to 27, when it will set about an hour after the Sun. However, it will be very close to the horizon and may be lost in the Sun’s glare.
While there is a possibility that Nishimura may fragment, increasing its brightness, it is less likely for a seasoned visitor like Nishimura. Nonetheless, the tail of the comet may still be visible as the sky darkens. Observers have estimated its length to be about six degrees and expect it to grow as the comet approaches the Sun.
If Nishimura does not provide the spectacle many hope for, there is a chance that another comet, Comet C/2023 A3 (Tsuchinshan-ATLAS), could deliver a truly spectacular show next year. Discovered earlier this year, its potential display is eagerly anticipated.