This comic strip has been making its way around the internet:

The final panel (which was added later) is clearly implying that Steve is watching the asteroid or comet that would eventually create the Chicxulub crater and cause the K-T extinction event.

Obviously it's just a joke, but I'm curious about the astronomy involved. Wikipedia says the Chicxulub impactor is thought to have been a 10-15 km diameter object. Would it have been visible to a (human) naked eye before impact? And if so, would it have appeared like a star that grew brighter and brighter each night?