There is a lot of excitement about Comet ISON, which might become a very bright comet, visible across the globe, by the end of 2013. But, before that happens, a second comet might become visible to the eye alone around the time it is closest to the sun in March of 2013. The Pan-STARRS telescope in Hawaii discovered this comet in June 2011. Since comets carry the names of their discoverers, it has been designated C/2011 L4 (PANSTARRS). Only the largest telescopes on Earth could glimpse Comet PANSTARRS when it was first discovered, but amateurs telescopes began to pick it up by May 2012. By October 2012, its surrounding coma was seen to be large and fine at an estimated 75,000 miles (120,000 kilometers) wide. In March 2013, by some estimates, this comet should get as bright as Venus, but do remember that comets are notoriously difficult to predict. As comet-hunter David Levy once famously said:
Comets are like cats; they have tails, and they do precisely what they want.
Look below for a month-by-month Comet PANSTARRS viewing guide.
Comet C/2011 L4 (PANSTARRS) was exceedingly faint when Hawaii’s Pan-STARRS 1 telescope discovered it on June 6, 2011.
March 5, 2013. Comet PANSTARRS passes closest to Earth at 1.10 Astronomical Units, (AU). One AU equals one Earth-sun distance, about 93 million miles or 150 million kilometers. In other words, this comet will pass slightly farther from us than our distance from the sun. No worries about it hitting us.
March 10. The comet passes closest to the sun – as close as our sun’s innermost planet, Mercury – at 0.30 AU – or about 28 million miles (45 million kilometers). 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. Not only will the comet quickly brighten, but it should also develop the long classic comet dust tail.
Throughout March 2013. The comet should be visible in the Northern Hemisphere evening sky low in the west after sunset. It will higher each night 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 should have its bright dust tail, and be visible to the unaided eye. It should, at least, if it lives up to expectations.
April 2013. No matter how bright it gets in March, the comet will surely fade as April arrives, as it moves away from the sun and back out into the depths of space. But it will be located far to the north on the sky’s dome and will be circumpolar for northerly latitudes in the Northern Hemisphere. That means it might be visible somewhere in the northern sky throughout the night for northern observers. What’s more, the comet will be near in the sky to another beautiful and fuzzy object in our night sky, the Andromeda Galaxy (M31), the nearest large spiral galaxy to our Milky Way. If the comet truly is bright then, and if it still has a substantial tail, it’ll be an awesome photo opportunity!
Comet PANSTARRS on the evening of April 6, 2013. This view is to the east that evening. The oval near the comet is the Andromeda galaxy. You’ll want a dark sky to see both the comet and the galaxy. Chart via Dave Eagle at www.eagleseye.me.uk. Used with permission. View larger.
By the way, Comet PANSTARRS is considered a non-periodic comet. It probably took millions of years to come from the great Oort comet cloud surrounding our solar system. Once it rounds the sun, experts say, its orbit will shorten to only 110,000 years. It is, for sure, a once-in-a-lifetime comet.
Bottom line: As 2013 begins, there are two comets to get excited about. One is Comet PANSTARRS, which will be brightest in March 2013. The other is Comet ISON, which might become a daylight comet in late 2013. Although a comet’s movement in our sky can be predicted, its brightness cannot be. It’s too early to know whether Comet PANSTARRS or Comet ISON – the two exciting comets of 2013 – will dazzle or fizzle. But these two are worth watching!
- EarthSky
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