According to Bakich (2012) of the Astronomy Magazine, the “brightest comet anyone alive has ever seen” will be visible to planet earth about a year from now. The comet named Comet C/2012 S1 or “ISON” was discovered by two astronomers Vitali Nevski of Belarus and Artyom Novichonok of Russia on September 21. It is predicted that the comet would be visible to the naked eye by late October or early November in 2013, and may reach or even exceed the brightness of the Full Moon. It will be visible to observers all over the world but those in the Northern Hemisphere will have a better vantage point since the comet will lie close to the North Star.
How comets form is a fascinating scientific mystery. Comets are made up of both silicate dust (which can only be formed at high temperature and pressure) and ice crystals (which would definitely melt at high temperatures). These components make the comets “shine” when it passes near the sun. So how come comets are made up of both silicate dust and ice crystals?
There were many studies conducted to elucidate the formation of comets. Spectral studies are performed to determine the chemical composition of comets from a distance, through the radiation that they emit. In a review made by Nuth (2001), he cited the work of Campins and Ryan which concluded that comets are made up of crystalline olivine based on its infrared spectra. Nuth (2001) and his colleagues further investigated on the probable temperature at which the crystalline olivine was produced. Results of their experiment suggest that crystalline olivine similar to that found in Comet Halley can be produced at temperatures close to 1000 kelvins in a matter of months. Further, they concluded that the formation of the crystals and ice mantle occurred at different regions of the nebula and could have not occurred at the same time.
References
Bakech, M.E. (2012). New comet will light up the sky. Astronomy, 9. Retrieved from http://www.astronomy.com/en/News-observing/News/2012/09/.
Nuth, J. A. (2001). How were comets made? American Scientist, 89. Retrieved from http://www.americanscientist.org/issues/feature/2001/3/how-were-the-comets-made/2.
