The so-called comet of the century is approaching us rapidly, and it may be one of the biggest astronomical events in recent history. Its name is Comet ISON, and speculation and predictions are rampant about the full effects it will have on planet Earth.
Comet ISON is a recently discovered space body found by Russian astronomers Vitali Nevski and Artyom Novichonok this past September. The two created a "night-survey" program that is named the International Scientific Optical Network, which utilizes observatories all over the world to study the sky. Thus, the comet they discovered was named ISON after the initials of their program, but is officially known as C/2012 S1. The Hubble Space Telescope in April discovered that ISON has a nucleus that is 3 to 4 miles across, quite smaller than many had expected. But the extraordinary aspect of the comet is its head, also known as the coma. The coma is approximately 3,100 miles across. Even more fascinating is ISON's tail. The head drags a tail that is 57,000 miles long, roughly 2.3 times the circumference of the earth. The enormous size of this comet and its close encounter with Earth in December could lead to some spectacular sights. However, these are dependent on one main aspect of the comet's journey: its point of proximity with the Sun, where the comet could potentially destabilize and break apart.
The most important date that will have the largest impact on the comet's life is November 28, Thanksgiving Day in the United States, when ISON will be 700,000 miles above the sun's surface. Its future is largely dependent on what happens then. "Comet ISON belongs to a class of comets called sungrazing comets. This means it will fly relatively close to our sun," Karl Battams of the Naval Research Lab told CNN. A NASA scientist offered a countered perspective to Battams. "Predicting the behavior of comets is like predicting the behavior of cats — can't really be done," Don Yeomans of NASA's Near-Earth Object Program explained. Zolt Levay, imaging team lead at NASA's Space Telescope Science Institute, explicated the role of the sun in Comet ISON's journey: "Material will start to come off the comet and increase the size of its atmosphere, the stuff around it, which reflects a lot of the light."
So what is in the future of ISON? Later on this year between September 17 and October 15, a huge science balloon is expected to launch from New Mexico in order to get a view of ISON without the interference of the atmosphere. The Balloon Rapid Response for ISON (BRRISON) mission will float up 23 miles (37 km) above the planet and observe ISON using a telescope with built in infrared and near ultraviolet/visible wavelength readers. BRISON should provide some clear views of ISON, and it is also set to bring in more information for analysis by astronomers as the comet makes its close approach to Earth. In November, ISON may be visible in the early mornings in the southeast parts of the sky. Starting in December, the comet, should it survive its pass-by on the Sun, will light up the Northern hemisphere for weeks and potentially even months. It will potentially be so bright that it will be visible all night long during these months. The comet passes right over the North Pole on December 26, just 39.9 million miles (64.2 million km) away from Earth. On the nights of January 14 and 15, the dust from the cloud's tail could potentially cause high-altitude clouds that glow after sunset, known as noctilucent clouds.