Something happened yesterday on Comet Holmes, an obscure comet fainter than Pluto. Until yesterday. From Space Weather:
Whatever is happening to Comet 17P/Holmes, it’s weird. "I’ve never seen anything like it! It almost looks like a planet," says Eric Allen …The comet has no tail, a remarkable golden color, and yesterday it shocked astronomers with a spectacular eruption, brightening almost a million-fold from 17th to 2.5th magnitude in a matter of hours.
To put that in perspective, this is similar to the brightness of stars in the Big Dipper or Orion’s Belt, easily visible to the unaided eye from within major light-polluted cities.
Unlike the traditional notion of a comet’s appearance, this comet has no visible tail. It’s just a small bright sphere, even in a telescope. To the eye, it’s more starlike in appearance than cometlike.
For a recent event, this makes sense, because a comet’s tail is formed by loose material with low mass and high surface area being blown away from the sun by the pressure of sunlight. Whatever broke free from Comet Holmes hasn’t had time to get affected by sunlight to form a tail.
The comet is favorably placed for observers in the northern hemisphere. It’s in the constellation Perseus, which is up all night at this time of year. Here’s a star map from Space Weather. I don’t know if the comet will stay bright or fade quickly, but it’s worth watching to see what happens next.
In other celestial news, the space shuttle was launched Tuesday. The orbital alignment isn’t favorable for visual observers in the United States, but there are a few passes that can be seen at southern latitudes (e.g. Florida, southern California). Predictions can be made at Heavens Above. I think there may be some better visual passes near the very end of the mission.