What's the difference between an atoll and an island?

With summer coming on, many people probably think atoll is simply what they pay to cross the bridge to their favorite island. But it's worth knowing the difference between these two geological formations.

An island is a chunk of land surrounded by water. Think of it as resembling the piece of Danish you might drink with your coffee. An atoll is more like a bagel. It began as a volcano in mid-ocean. But then the volcano sinks below sea level, leaving just the coral that forms on the rim of the crater. Soil forms on top of the coral, producing an island- like circular formation with a lagoon in the middle. The formation, or atoll, found most often in the Pacific, is also referred to as a coral reef.

As I said, the distinction is worth knowing - unless you're a fish, to whom, I imagine, it doesn't matter atoll.

MercuryThis is taking a year and a day. If you were on the planet Mercury, it would seem like a year or more from one day to the next. That's because Mercury, being close to the sun, revolves around it in only 88 days, completing one year. But it takes twice as long as that for Mercury to make one full rotation on its axis thus completing a full day. If you were at the office on Mercury, the day would go even slower.