Comet PanStarrs comes closest to the Earth today, to be visible from March 10 onwards in northern hemisphere

By- 

Akshay Deoras 

The Comet McNaught in Jan 2007.

 The visuals of the comets like Halley, Hale-Bopp,McNaught generate instantaneously in the minds of the people who have seen them in person! However there are many people (including me) who haven't seen a comet in the sky .The wait to see the comet in the sky seems to be getting over this year when two comets namely Comet PANSTARRS (C 2011/L4) and Comet ISON (C/2012 S1) will provide a celestial treat to the eyes.Comet ISON might be visible to the eyes during later 2013. 

Courtesy nature.com. The relative positions of Oort Cloud and the Kuiper Belt- Wombs of the Comets. 

A comet is a celestial object having three main components prominently when its approaching a star (Say our Sun). The permanent feature with a comet is its nucleus. The nucleus of the comet is made of rocky material,dust,ice,frozen gases like methane,carbon monoxide,carbon dioxide etc having a radius from a few meters to around 30-40km (Although there is no upper limit). The comets are born in either of the two regions called as the Oort Cloud and the Kuiper Belt. The Kuiper Belt is a region which lies beyond the orbit of Neptune within the estimated limits of 30AU to 50AU ( 1AU= 149.6 Million Km) from the Sun. This region has a large amount of objects having composition similar to a comet's nucleus. Dwarf Planets like Pluto also lie in the Kuiper Belt. As this region lies closer to the Sun than the Oort Cloud, it is believed that the short period comets originate in this region. The Oort Cloud (not observed till now) is believed to lie even further away from the Sun and the Kuiper belt at a distance of roughly ~2000AU from the Sun. Due to its distance, its believed that the long period comets like Hale-Bopp were born in this region. As a comet approaches the Sun in its orbit, the heat of the sun coupled with radiation pressure, solar wind etc lead to the sublimation of these volatile materials and a few other things. This leads to the formation of atmosphere type region around a comet's nucleus which is called as "Coma" of a comet. 

The dust tail is colored yellow whereas the ion tail is blue

A comet briefly has two tails (although a rare antitail in some cases)- An ion tail ( made of ions and having its own luminance) and a dust tail ( illuminated by the Sun's light and made of fragments of the nucleus). 

Comet ISON.

Comet ISON's exiting the inner solar system. Above view of the orbit on Dec 11 2013. Courtesy- NASA/JPL

Designated as C/2012 S1 (ISON), Comet ISON is already the most popular comet of this year even when majority of the people haven't seen it in the sky.If you read the related news,you will find adjectives like 'Comet of the century' etc for it. The comet has a nearly parabolic orbit and at present is approaching towards the perigee with respect to Sun ( perigee is a point in the non circular orbit of any object in which it is the closest from that object it is orbiting) which will happen on 28 Nov 2013. This comet has a potential to be visible to the eyes after its perigee. It will all depend on how much it survives the sun. I will write separately on it later this year. 

 Comet PANSTARRS-

Comet PanStarrs from Argentina. Courtesy- Luis Argerich (http://www.luisargerich.com/)

Designated as C/2011 L4, this comet was discovered using the PAN-STARRS telescope at Maui,Hawaii. PAN-STARRS stands for Panaromic Survey Telescope And Rapid Response System-an agency which scans for objects like comets,asteroids in the sky. It was discovered in June 2011. 

On 5th March I.e today, the comet comes closest to the Earth at a distance of 1.097 AU (1AU= 149.6 Million Kilometers).This comet is already visible in the Southern Hemisphere however as it heads  for a perigee with the Sun on 10th March at a distance of 0.30AU from the Sun, it will no longer be visible from the Southern Hemisphere. 

Comet PanStarrs on 5th March. Courtesy- NASA/JPL

From around 7th-8th March, this comet will slowly be visible for the Northern Hemisphere people in the western sky shortly after the sunset. As the comet will be in the lower western sky (after the sunset), it may not be visible through the binoculars or small telescopes as the twilight will interfere with the visibility particularly if observed from any city.The comet will brighten up due to the increased heating by the Sun during the perigee and hence the tails will become brighter from 10th March onwards.

Projected location of Comet PanStarrs on 11th March 2013. The view is for Nagpur,India

( 21.15N,79.09E).

To view this comet, a clear,unobstructed view of the western horizon must be there with a clear sky.People should look slightly above the western horizon shortly after the sunset through binoculars or a telescope ( the ideal location will be a remote place which is free from lights and pollution). The best viewing seems to be during 11th,12th,13th Mar. 

The waxing crescent moon will act as a guide in spotting the comet in the lower western sky from 13th Mar onwards but will interfere with the visibility of the comet. Below image shows the situation of 13th March from Nagpur,India. The moon will be below the comet as seen in the sky with Mars also in a range such that a triangle will form between the three.

On 14th Mar, the comet will appear between the moon and the western horizon and thus will be easy to spot. Below image shows how the young waxing crescent moon with look in the vicinity of the comet.

The comet will be there in the sky (visible to telescopes) throughout the march. However sighting isn't assured then! So  do hunt this comet in Mid March itself!!!