We now have a fine opportunity to view the planet that many astronomy guide books refer to as the most difficult of the naked-eye planets to see. The planet in question is Mercury. Beginning now ...

Caption This is an image of Mercury's tail obtained from combining a full day of data from a camera aboard the STEREO-A spacecraft. The reflected sunlight off the planet's surface results in a ...

And yet, despite its reputation, Mercury is not really that difficult to spot; just find a reasonably unobstructed horizon. A clear, haze-free sky also helps. The remark about Copernicus is rather ...