¡SkyCaramba! Weekly astronomy blog for the week of November 15 to 21, 2015
At the start of this week, a comet named Catalina is at perihelion and whipping around the sun. It will head north of the sun and emerge in the morning sky for a northern hemisphere audience. How well can you see it? That depends on a number of things.
Astronomers with binoculars and small telescopes were able to see the comet before it was closest to the sun. It will probably remain visible that way after perihelion. Of course, everyone hopes for a naked eye comet. Whether that will happen is hard to predict. Scientists have been wrong about such things before. Few are willing to take the risk of making a prediction.
Going close to the sun helps brighten a comet. Not only is it receiving more sunlight to reflect, the solar wind is stronger and tends to loosen up more comet material which, in turn, reflects even more light. Catalina will be 0.83 astronomical units from the sun. That’s 83% of the average distance the earth is from the sun. Many comets have gone closer without achieving naked eye brightness. But there’s still more to ...