As it happened: All eyes on Chinese space station Tiangong-1 as it plummets to Earth

An out-of-control Chinese space station the size of a school bus has mostly burnt up on re-entry over the Pacific Ocean.

Although it's not the biggest piece of space junk to crash into Earth, it certainly piqued global attention on the way down.

Because of the high speed of the returning satellite it was difficult to predict exactly where it would land. Tiangong-1 crashed into the South Pacific near Tahiti on Monday afternoon.

These live updates have now ended.

5:25pm: New Zealand has never been damaged by space junk, but in September 2006 a sonic boom possibly caused by a spacecraft fragment shocked Canterbury.

Christchurch residents reported the boom took place just before 3pm, and was powerful enough to shake buildings across the region.

At the time, experts at Stardome Observatory in Auckland told NZME it may have been a meteor.

Police instead believed the cause was a harmless piece of space junk re-entering the atmosphere.

4:23pm: China's follow up to Tiangong-1, Tiangong-2, is already in orbit, having been launched in September 2016.

This was only six months after data transmission between China and the first space station disappeared in March 2016.

In similar fashion to its predecessor, Tiangong-2 is only designed to be used temporarily. China is now working on a permanent station which could be used from 2022 onward, reports.

4:03pm: Dr McDowell is warning people to avoid using real-time satellite tracking sites promising Tiangong-1 updates, as many of them are out of date.

"All of these sites which let you track where a satellite is orbiting are GREAT … for seeing when a satellite in a stable orbit is going to come overhead," he wrote.

"But you CANNOT use them for re-entries. Why?

"Because these sites run off a set of orbital data that they only update occasionally - perhaps once every few days.

"That's fine for [satellites] whose orbits don't change but no good for a situation like today."

3:51pm: It's difficult to say whether there will be any effect on New Zealand from the crash, Dr Rattenbury said.

"It really depends on what, if anything, landed. I've yet to see any reports of evidence that anything made it through the atmosphere.

"If there had been anything which had made it down to the surface of the earth if those materials were denser than water they would sink."

3:42pm: According to Dr Rattenbury, the toxic materials on the space station that everyone was fearing were likely not a threat.

He said it's probable they would have burnt up on the way to the ocean.

"[It's] likely most things in the spacecraft would have burnt up," he said. "Including the propellant."

3:35pm: Tiangong-1 isn't the largest piece of space junk to have fallen to earth - that honour belongs to Russia's Mir space station.

Mir was brought down in a controlled re-entry in 2001, causing New Zealand to issue an international warning to ships and airplanes travelling in the South Pacific area.

Debris from the re-entry spread about 1500 kilometres along trackm and 100 kilometres laterally.

3:26pm: Dr Nicholas Rattenbury, senior lecturer in physics at the University of Auckland, told Newshub more about the "space graveyard" Tiangong-1 missed on the way down.

He said the graveyard is likely to be a place where spacecraft are condemned to rest after a controlled return to the Earth's atmosphere.

"There's going to be places on the Earth's surface where you would try to ditch a spacecraft under controlled conditions," he said.

"I suspect that this region… is one of those."

2:28pm: Social media users are farewelling Tiangong-1 now that it has reached its final resting place near Tahiti.

"Weeks digging a bunker. Months stockpiling episodes of The Good Wife and the original Hollywood Squares.

"36 pounds of tin foil. Six cases of Marmite. And the danged space station goes down in the ocean," one user wrote.

1:55pm: While some may have worried about Tiangong-1 hitting them, there is only one recorded case of space junk actually hitting a person - and she lived to tell the tale.

In 1997, Lottie Williams was out for a walk at 3:30am in Tulsa, Oklahoma when she saw a bright light streak across the sky.

Soon afterwards, she felt something bounce off her shoulder and noticed a piece of light metallic material on the ground behind her.

Later analysis showed it was piece of a rocket that had been launched nine months earlier, carrying a military satellite.

Ms Williams was completely unharmed in the experience.

1:45pm: Tiangong-1 has crashed into the South Pacific near Tahiti. According to Dr McDowell, it just managed to miss the "space graveyard" that junk often crashes into.

1:20pm: The US Joint Force Space Component Command has confirmed ananysis suggesting Tiangong-1 has reentered the atmosphere above the South Pacific. 

1:10pm: The space lab has re-entered the atmosphere above the South Pacific 'mostly' destroyed, AFP reports.

There are no reports yet on whether the remainder has crashed.

12:45pm: The space station is now tracking over the Atlantic Ocean towards Africa. It could soon be visible above Cote d'Ivoire and Ghana, where it is currently 12:45am.

12:43pm: So far no reports are coming in of people seeing Tiangong-1 over South America, astronomer Jonathan McDowell says.

It is reportedly overcast in Uruguay and Buenos Aires which may explain why it could not be seen.

12:30pm: According to Aerospace, Tiangong-1 has reentered the atmosphere just west of Chile, as predicted.

Even after the Chinese space station hits Earth, it could be hours before we know for sure, astronomer Jonathan McDowell has pointed out.

12:25pm: Aerospace predicts there are now six minutes until re-entry.

12:23pm: The space station is now over the point, west of Chile, where Aerospace predicted it would re-enter Earth's atmosphere.

12:20pm: Tiongang-1 is now around 140 kilometres above Earth.

12:15pm: According to Aerospace, there may be only 20 minutes until Tiangong-1 hits Earth.

The nine-tonne space station will mostly burn up on descent and is unlikely to cause any damage, China Manned Space Engineering Office says in a statement.

But Andrew Abraham, a member of the The Aerospace Corporation, said there's a "10 percent to 40 percent" of it surviving its descent back to Earth.

12:00pm: An astronomy enthusiast has posted flashback footage of an unmanned cargo resupply spacecraft re-entry in 2008.

Footage shows the bright lights shooting across the sky above the Pacific Ocean in 2008.

The spacecraft was launched by the European Space Agency.

There is a high chance today's re-entry will also take place over the ocean.

11:45am: Aerospace's current re-entry prediction has Tiangong-1 coming back into Earth's atmosphere slightly west of Chile and Argentina. The satellite is currently above Mongolia.