Flight 370 has disappeared for nearly 48 hours already and it has yet to be recovered. Investigators from numerous countries are trying to piece together just what took place. Here are all the things we still don't know.

1. The location of the plane

Search and rescue have been combing through the South China Sea for over a day but no luck of any evidence of the plane's location.

Vietnam released a photo of debris that it thinks might be from Flight 370. The country also announced that it thinks it has found parts of the plane's tail as well as fragments of an inner door. It has yet to be confirmed.

Earlier on Sunday, a Singaporean search vessel came upon a yellow floating object, but it was determined to be unrelated to Flight 370. At least 40 aircraft and 12 vessels are looking for the plane. Australia, Singapore, China, and the U.S. are among countries assisting in the search.

Vietnam also released a photo on Saturday of what it believes to be miles-long oil slicks in the water off the country's southern coast. No concrete link to the plane.

2. Why the plane vanished

Authorities are unsure when the pilots realized the plane was in trouble. An unnamed pilot spoke to a Singapore newspaper yesterday and said that he made contact with Flight 370 minutes after the plane's final communication with air traffic control. The pilot does not remember his brief contact with the plane being suspicious or under distress.

Meanwhile, an AP report cites unnamed Malaysian officials as stating that radar images show that the plane may have attempted to turn back before it finally disappeared from radar.

Malaysian officials say they are investigating whether the plane disintegrated in mid-air.

"The fact that we are unable to find any debris so far appears to indicate that the aircraft is likely to have disintegrated at around 35,000 feet," a source involved in the investigations in Malaysia told Reuters.

3. Was it a terror act?

Officials from a number of countries have confirmed that they are looking into the identities of two passengers who boarded the plane using stolen passports. The Malaysian government is investigating if up to four people boarded the jet with false paperwork.

According to CNN, the two passengers in question — one of whom possessed a stolen Italian passport, the other a stolen Austrian passport — appear to have purchased their tickets together, using Thai currency through South China Airlines.

According to the New York Times, a preliminary Pentagon investigation of "flash" data did not detect any evidence of an explosion in the area where the plane is thought to have disappeared.

In regards to the stolen passports, an American official said that while it is interesting, it doesn't necessarily say that it was a terror act.

More updates to come.