People praise touching thing astronaut did as NASA caught harrowing footage of 9/11 from space

Viewers have praised what an astronaut did after footage caught from space following the tragedy of the 9/11 was released.

Originally caught by a NASA space explorer, it has was then released by Channel 4 Entertainment in 2014 as astronauts onboard the International Space Station (ISS) sat 250 miles above the surface, observing the horror event.

Occurring almost 23 years ago, the biggest terrorist attack in world history occurred when two planes crashed into New York City's World Trade Center and another flew into The Pentagon in Virginia.

Almost 3,000 people died on 11 September 2001, as thousands more were injured, with families and friends left scarred by the loss of their loved ones.

The attack on the Twin Towers and the Pentagon began the US' war on terrorism. (Education Images/Universal Images Group via Getty Images)

You've probably seen coverage of the second plane crashing into the the World Trade Center, with it being caught live on several TV broadcasts, so the chilling footage has been out there for years.

But many people may not be aware that there is footage that exists from the ISS, where astronauts, like many on the ground, were unsuspecting and idle, helpless to what they were seeing.

The footage captured of 9/11 comes from the only American onboard the space station at the time, Frank Culbertson, who called home base and was informed of what was happening on the ground that day - and he was distraught.

He then picked up a video camera and went to a window facing New York, and as the weather was clear, he could film the Big Apple perfectly.

Footage eerily revealed the huge column of black smoke that came from the World Trade Center, which Culbertson explained: "I could see this big grey blob enveloping southern Manhattan - what we were seeing was the second tower come down."

Admitting that it was hard to be away from his loved ones during the scary time, he said that NASA arranged a phone call with his wife that evening, and the astronaut felt better when he learned that her and their kids would be okay.

In his video, he then sent a message to New Yorkers, saying that their city was still 'very beautiful' from space.

However, an emotional moment came later on, when Culbertson was informed about hijacking of the America Airlines flight 77.

"The next day, I got a call from the ground and he said Frank I've got some

bad news, it turned out that the captain of America Airlines flight 77 that crashed into the Pentagon was a friend of mine, Chic Burlingame," he said.

The astronaut gave his ex-classmate a heartfelt tribute from space. (Channel 4 Entertainment)

The astronaut said that the pilot was a classmate of his in the Navy, and was going to send a message to his ex-classmates anyway, but made a special tribute to his friend.

Having been in the Drum and bugle corps together, he played an emotional rendition of 'Taps', a bugle call that signals 'lights out' at the end of a military day, during memorial ceremonies, or during military funerals.

Describing it as a 'final farewell', Culbertson was clearly emotional as he played his bugle for his late friend.

Users found this to be incredibly touching, as one commented: "3:12 was very touching and respectful. Tears naturally fall."

Another said: "This was sad but beautiful."

While a third shared: "It’s insane to know that when the second tower came down, our only American in space at the time witnessed it as it happened."

A different user said: "What an amazing way to pay respect to his friend and classmate. Taps from the ISS is one hell of a tribute for a lifetime of service."