The farther south in the U.S., the better chance you have to see Comet C/2011 L4, also known as Comet PANSTARRS. It gets its name from the Panoramic Survey Telescope and Rapid Response System in Hawaii that discovered it in June 2011.
March 10. This is a good time to look for Comet PANSTARRS from U.S. latitudes. The comet should be visible, and it’ll be at its brightest. Why? The comet passes closest to the sun – as close as our sun’s innermost planet, Mercury, about 28 million miles (45 million kilometers) away – on March 10. Comets are typically brightest and most active around the time they are closest to the sun when solar heating vaporizes ice and dust from the comet’s outer crust. Expect the comet to brighten quickly around this time. Look for it low in the west after sunset. Bring binoculars to help you spot it in the twilight sky.
Around March 12 and 13. Moonlight might interfere a bit with the darkness of the night sky, but there should be some wonderful photo opportunities as the young moon returns to the same part of the sky as the comet.
Throughout March 2013. The comet could be visible in the Northern Hemisphere evening sky low in the west after sunset. It will move northward each evening during March 2013 as it moves from being in front of the constellation Pisces to being in front of the constellations Pegasus and Andromeda. At this time, the comet might have a bright dust tail, and perhaps visible to the unaided eye or binoculars. It should, at least, if it lives up to expectations. Remember to look for the comet in the vicinity of the waxing crescent moon on March 12, 13 and 14. The comet swings above the star Algenib on March 17/18, and above the star Alpheratz on March 25/26.
I find it interesting that the comet had an apparent magnitude of 19 when it was discovered and that the predicted brightness at perihelion has been changed over the last month. Comet PANSTARRS will still be visible to the naked eye, but it won’t be as spectacular as Halley’s Comet (-1 apparent magnitude), probably closer in apparent magnitude to the M31 Andromeda Galaxy (+3.4).