Scientists have turned the Hubble Space Telescope toward Comet Holmes in an effort to learn more about what caused the once-dim speck to blossom suddenly on October 23 into a naked-eye object in the evening sky. Here's the Web site that explains all, with lots of pictures of the comet and its nucleus - the size of Central Park.
UPDATE: Friday morning. When skies cleared last night I grabbed the binoculars and had another look at Holmes. I was amazed by how much bigger the cloud of dust and gas around the comet's nucleus has grown since my last look a week or more ago. Scientists say it is now about the same size as the sun, although it's a whole lot less substantial.
Holmes has become almost invisible to the naked eye - at least where I was observing - as it's expanded and dimmed. But it was easy to find in the binoculars. I also noticed how much Holmes has moved since my last look. It's rising higher in the northeastern sky in the evenings, closer to the apex of the triangle of stars I used to find Holmes a week ago.