5 Things to Know This Morning

— -- Your look at the five biggest and most buzz-worthy stories of the morning.

1. Obama Authorizes Air Strikes, Humanitarian Aid Mission in Iraq

President Obama said Thursday he has authorized "targeted" air strikes if necessary to protect American interests in Iraq from insurgent forces that are taking over the country's northern cities.

If the terrorist group ISIS reaches Erbil, the president said he will call in U.S. air strikes. The U.S. has an embassy and other staffers in the city. Air strikes have also been authorized to protect families fleeing ISIS in the Sinjar Mountains.

"These innocent families are faced with a choice: descend and be slaughtered or stay and slowly die of hunger," he said.

2. WHO: Ebola Outbreak Is a Public Health Emergency

The World Health Organization on Friday declared the Ebola outbreak in West Africa to be an international public health emergency that requires an extraordinary response to stop its spread.

It is the largest and longest outbreak ever recorded of Ebola, which has a death rate of about 50 percent and has so far killed at least 932 people. WHO declared similar emergencies for the swine flu pandemic in 2009 and for polio in May.

The WHO chief, Dr. Margaret Chan, said the announcement is "a clear call for international solidarity" although she acknowledged that many countries would probably not have any Ebola cases.

"Countries affected to date simply do not have the capacity to manage an outbreak of this size and complexity on their own," Chan said at a news conference in Geneva. "I urge the international community to provide this support on the most urgent basis possible."

3. What Happened to Baby Melissa? NJ Police Reopen 26-Year-Old Cold Case

Melissa Diane McGuinn was just 7 months old when she disappeared from her Trenton, New Jersey, home. More than 26 years have passed, but her mother remains convinced that her only daughter is out there somewhere.

“I’ve always felt in my heart that she is out there,” Becky McGuinn House said. “It’s not just a whimsy feeling. It’s a strong feeling. I feel she is alive.”

4. Iselle Downgraded to Tropical Storm as it Approaches Hawaii

Hawaii residents are urged to stay indoors and classes were canceled as the islands brace for two major storms.

Iselle, which has brought rain and wind to the Big Island overnight, was downgraded to a tropical storm as it approached landfall, with maximum sustained winds of 70 miles per hour, below the minimum of 74 mph for a hurricane. The storm is poised to become the first hurricane or tropical storm to hit the island chain in 22 years.

Another storm, Hurricane Julio, is about 1,000 miles behind in the Pacific.

5. Richard Nixon Resigned 40 Years Ago

On this day in history 40 years ago, Richard Nixon – facing all but certain impeachment amidst the Watergate scandal – announced his decision to resign as president.

The Watergate scandal was touched off by the June 17, 1972 break-in of the Democratic National Committee’s headquarters in Washington, D.C.

"I have never been a quitter. To leave office before my term is completed is abhorrent to every instinct in my body. But as President, I must put the interest of America first. America needs a full-time President and a full-time Congress, particularly at this time with problems we face at home and abroad," he said in his resignation speech.