I assume you are asking about C/2009 P1? This comet is no threat to Earth as it doesn't come anywhere near Earth. Its closest approach to the sun is about 1 1/2 times the size of Earth's orbit.
Halley's Comet is not dangerous to Earth. It poses no threat to our planet and its orbit is well-studied, so we can predict its movements accurately. The last time it was visible from Earth was in 1986, and it is not expected to return until 2061.
In mid-September 2011, the following comets are brighter than magnitude 12 as seen from Earth: -- P/2007 R5 SOHO -- C/2010 X1 Elenin -- 45P Honda-Mrkos-Pajdusakova -- C/2009 P1 Garradd
In mid-September 2011, the following comets are brighter than magnitude 12 as seen from Earth: -- P/2007 R5 SOHO -- C/2010 X1 Elenin -- 45P Honda-Mrkos-Pajdusakova -- C/2009 P1 Garradd
In mid-September 2011, the following comets are brighter than magnitude 12 as seen from Earth: -- P/2007 R5 SOHO -- C/2010 X1 Elenin -- 45P Honda-Mrkos-Pajdusakova -- C/2009 P1 Garradd
In mid-September 2011, the following comets are brighter than magnitude 12 as seen from Earth: -- P/2007 R5 SOHO -- C/2010 X1 Elenin -- 45P Honda-Mrkos-Pajdusakova -- C/2009 P1 Garradd
The scale of damage potentially caused by an asteroid or comet impacting Earth is known as the Torino Scale. It is used to communicate the potential threat level of near-Earth objects (NEOs) impacting our planet.
At the end of December 2011, the following comets are all brighter than magnitude 12 as seen from Earth: -- C/2009 P1 Garradd -- P/2011 Y1 Levy -- C/2011 W3 Lovejoy -- 21P Giacobini-Zinner
The sun is the largest out of the three and then the earth and then a comet.
Comet 'Elenin' essentially fell apart in August 2011, on account of some unusually high solar activity. Those components of it that vaporized quickly dissipated in space. What's left is a cloud of sand, pebbles, stones, and possibly some ice chips, in the comet's original orbit. It was never a threat to Earth, and is even less of a threat now than it ever was.
comet sandy
The name of the comet that will pass Earth on August 15, 2011, is the comet Honda.
We don't currently know when a comet will hit planet Earth.