Scott Neuman

A bipartisan compromise that would have expanded federal background checks for firearms purchases has been rejected by the Senate.

The defeat of the measure by a 54-46 vote — six votes shy of the number needed to clear the Senate — marks a major setback for gun-control advocates, many of whom had hoped that Congress would act to curb gun violence in the wake of December's Newtown elementary school massacre, where 20 students and six adults were killed.

Scientists have unraveled the genome of the coelacanth, a rare and primitive fish once thought to be extinct, shedding light on how closely it's related to the first creatures to emerge from the sea.

The coelacanth, a fish that can reach up to 5 feet long and lives in deep ocean caves, had only been seen in fossils and was thought to have gone extinct some 70 million years ago. That was until 1938, when fishermen from the Comoros islands off the coast of Africa captured one in a net. A second coelacanth species was discovered off the Indonesian island of Sulewesi in 1997.

Update at 6:21 p.m. ET. Launch Delayed:

Space.com reports that the Antares rocket launch has been delayed for two days, "after an unexpected glitch."

Space.com reports:

American Airlines has promised passengers that Wednesday's flight schedule will be nothing like the day before, when thousands were stranded due to a glitch in the reservations system that forced hundreds of flights to be canceled or delayed.

American Airlines and American Eagle scuttled 970 flights and delayed more than 1,000 others Tuesday, The Associated Press said, citing flight-tracking service FlightAware.com.

A computer glitch in the reservations system at American Airlines caused all of the carrier's flights to be grounded for at least two hours on Tuesday.

"American's reservation and booking tool, Sabre is offline," American Airlines spokeswoman Mary Frances Fagan told Reuters in an email. "We're working to resolve the issue as quickly as we can. We apologize to our customers for any inconvenience."

NPR's Wade Goodwyn reports that the outage was announced about 2:30 p.m. Eastern time.

Pope Francis' doctrinal chief has reaffirmed the Vatican's intention to overhaul the largest organization of U.S. nuns, dashing the hopes of some that the newly installed pontiff would take a more conciliatory approach than his predecessor.

Hugh Heffner's empire has run afoul of conservative politicians in India, who have decided to halt plans for the country's first Playboy Club.

PB Lifestyle, the Indian firm with rights to the Playboy brand, had hoped that the club in the southwestern state of Goa would be the first of eight to be constructed over the next three years. They were hoping for as many as 120 such clubs in the coming decade.

China on Tuesday detailed the structure of its military force in a special national defense report that also took a swipe at the United States for what it described as stoking tensions in the Asia-Pacific region.