Comet C/2012 S1 ISON was one of the most prominent astronomical events of 2013. Discovered in 2012 by astronomers Vitali Nevski and Artyom Novichonok at the ISON (International Scientific Optical Network) observatory in Russia, ISON quickly became the focus of scientific and public attention. With an orbit toward the Sun, many people hope this comet will become one of the brightest comets ever observed from Earth, even visible to the naked eye.
However, the 2013 event did not go quite as predicted. As comet ISON approached the Sun, the heat and pressure from the central star caused it to break apart, leaving behind a brief but impressive display. The story of comet ISON has become a powerful testament to the complexity and unpredictability of celestial bodies in the Solar System.
1. Discover Comet ISON
Comet C/2012 S1 ISON was discovered on September 21, 2012, when it was still very far from the Sun, about 950 million km away. Soon after, astronomers began studying its orbit and found that ISON would have an extremely close approach to the Sun, only about 1.16 million km from the Sun’s surface. This causes ISON to be called a “sungrazing comet”.
Initially, astronomers predicted that ISON could become one of the brightest comets ever observed from Earth. As it approaches the Sun, the comet will evaporate rapidly, creating a huge tail of gas and dust, clearly visible in the sky. This has made many people expect a rare and memorable astronomical event in 2013.
2. Journey to Approach the Sun
In late November 2013, comet ISON began its closest approach to the Sun. Space telescopes such as SOHO (Solar and Heliospheric Observatory) and NASA’s STEREO continuously monitored the comet throughout its journey. Images from these telescopes show that comet ISON has brightened significantly as it approached the Sun, giving many scientists even more hope for a great light show.
However, when ISON came closest to the Sun on November 28, 2013, the comet began to show signs of breaking up. The heat and gravity from the Sun made ISON’s icy nucleus unbearable, causing the comet to break into many pieces and gradually disappear. Although the comet’s debris remained visible for several days afterward, Comet ISON was no longer bright enough to become a visible phenomenon as originally expected.
3. Cause of ISON’s Breakup
Comet ISON broke up when it got too close to the Sun due to the impact of extremely high temperatures and strong gravity. When approaching the Sun, the temperature at ISON’s surface may have exceeded 2,000 degrees Celsius, enough to melt the icy material in the comet. In addition, the Sun’s gravitational stretch created strong pressures on ISON’s nucleus, leading to its breakup.
Comet ISON may contain a variety of ices such as water, CO2 and methane. As these ices rapidly evaporate in the heat from the Sun, they create a large cloud around the comet, creating what we call a “comet head”. However, when these ices melt too quickly, the comet’s nucleus is no longer cohesive enough to maintain its shape, and as a result it breaks into many small pieces.
4. The Legacy of Comet ISON
Although it did not produce as spectacular a light phenomenon as predicted, Comet ISON still left an important legacy in the field of astronomy. It has helped scientists get more data about comets, especially comets with orbits close to the Sun. Tracking ISON’s journey provides information about how comets react when exposed to extremely high temperatures, and this could help predict similar events in the future.
Images and data from space telescopes such as SOHO and STEREO have helped shed light on how comets change in the harsh environment near the Sun. Although Comet ISON did not leave a spectacular mark on Earth’s sky, it did open the door to a better understanding of “sun-grazing” comets and related phenomena.
Comet ISON
Comet C/2012 S1 ISON was one of the most notable astronomical events of 2013, although the ending was not as expected. ISON’s journey has brought valuable knowledge to the astronomy community and highlighted the unpredictability of comets in the Solar System. Although Comet ISON failed to become the “brightest comet of the century” as many expected, it still left a lasting scientific legacy and expanded human understanding of comets.
