Four hundred miles out in space, NASA's Aqua satellite has taken pictures of the oil slick in the Gulf of Mexico caused by the explosion of the Deepwater Horizon drilling rig. In this image from Sunday, the center of it is about even with the mouth of the Mississippi River. We're told it covers 400 square miles. Take a look. The Coast Guard says 42,000 gallons of oil are leaking from the well into the gulf daily (forgive me for omitting the word earlier). By oil-spill standards, it is big but not record-setting; the Exxon Valdez, 21 years ago, spilled close to 11 million gallons into much colder waters. The Gulf of Mexico has the advantage of being warm; about 75 percent of the oil, say engineers, may evaporate before it can reach the Louisiana coast. But that still leaves plenty, and spill cleanup is not a science. If you know Louisiana geography (if not, there's a Google map HERE) you'll be able to pick out New Orleans in the upper left, and, just to the north of it, Lake Pontchartrain. The lake is about 40 miles across from east to west. The oil slick would probably fill it.