Approaching Comet ISON Could Be Spectacularly Bright
A comet is approaching Earth that could be brighter than the moon when it passes by. But first it has to survive its trip here. Discovered in September 2012 by two Russian amateur astronomers, comet ISON will fly within 1.2 million miles (1.9 million kilometres) from the centre of the sun on November 28th, 2013.
As the comet approaches the sun, the intense heat will melt ice on the comet, creating what could be a spectacular tail that will be visible in the night sky without the need for a telescope or binoculars from October 2013 through to January 2014. However, this is a chance that comet ISON could break apart as it nears the sun, or it could fail to create an ice tail that will be visible from Earth.Credit: Wikimedia
Comets like ISON come from the Oort Cloud, a cluster of frozen ice and rocks that orbit the sun roughly 50,000 times further away than Earth’s orbit. Occasionally, one of these frozen ice rocks is bumped from the cloud and slowly orbits around the sun.
The two Russian astronomers spotted comet ISON on images taken by a 16-inch telescope that is part of the International Scientific Optical Network, or ISON, for which the comet is named after.
The path the comet ISON is taking to approach is very similar to a comet that passed by Earth in 1680, which was reportedly so bright that its ice tail could be seen during the day. In fact the path is so similar to that 1680 comet that some scientists are even wondering if it is a fragment from the same parent comet.
British astronomer David Whitehouse wrote that comet ISON “could be the brightest comet seen in many generations - brighter even than the full moon."
In 2013, Earth, and its inhabitants have two opportunities to see a comet show. Comet Pan-STARRS is due to pass by the planet in March, eight months before ISON's arrival. The last comet to light up Earth's night-time skies was Comet Hale-Bopp, which came within 122 million miles (197 million kilometres) of Earth in 1997. It had an unusually large nucleus, roughly 18 to 25 miles (30 to 40 kilometres) across. This gave off an enormous amount of dust and gas that was visibly bright to the naked eye.
In 1994, the comet Shoemaker-Levy 9 collided spectacularly with Jupiter in 1994. The gravitational force from the giant planet ripped the comet apart before it impacted, with the largest collision creating a fireball that went roughly 1,800 miles (3,000 kilometres) high and left a giant dark spot more than 7,460 miles (12,000 km) across — about the size of the Earth —and was estimated to have exploded with the same force as 6,000 gigatons of TNT.
Perhaps the most well known comet is Halley’s Comet. Visible only every 76 years when it orbits the sun, Halley’s Comet was even depicted in the Bayeux Tapestry that chronicled the Battle of Hastings of 1066. It was last seen in 1986, so if you can’t wait until 2062, make sure to check out comets Pan-STARRS and ISON as they float our way this year.