The top-secret Aurora project was first first reported on in 1989 and it could be behind Lockheed Martin's SR-72 plane concept

Conspiracy theorists say power source could be behind a hypersonic US spy plane, dubbed Aurora

The origin of the mysterious bangs heard across the UK and New York at the weekend are yet to be officially identified.

But a leading theory is that they were created by an aircraft possibly travelling at supersonic or hypersonic speeds above the Atlantic.

This has led conspiracy theorists to attribute the booms to a spy plane rumoured to be under development by the US military, under the codename Aurora.

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Aurora is rumoured to be a top secret aircraft that has been in development since 1989. These claims originated in Aviation Week and Space Technology magazine in 1989. In November 2013, Lockheed Martin announced it was developing a similar SR-72 spy plane (illustrated) said to be able to accelerate up to Mach 6

Dr Bhupendra Khandelwal, an engineering research associate from Sheffield, claims the loud bangs were created by a type of experimental jet engine called a pulse detonation engine.

Claudia Angiletta, a resident from Croydon, South London, recorded the sounds as she was watching TV at home at around 10pm GMT on Saturday.

Within minutes, Twitter users had started spreading hashtags - from the straightforward #loudbangs to the somewhat melodramatic #omgwereallgoingtodie.

At around the same time, residents in locations including Buffalo, Cheektowaga, Clarence and as far north as Niagara Falls on the east coast of the US also took to social media to report the unusual noises.

It's conceivable that with that sort of power, speed, and altitude, the sound would carry over a vast distance. #hypersonic #loudbangs — Brailsford (@AviateX14) December 1, 2014

The continuous noise and odd sound it makes would then be explained by reverberations around the stratosphere. #loudbang #hypersonic — Brailsford (@AviateX14) December 1, 2014

It seems to me that everyone has ruled out sonic booms, no one is considering hypersonic booms, both US & China developing it #loudbangs — Brailsford (@AviateX14) December 1, 2014

Twitter user Brailsford believes the noises were created by hypersonic booms (tweets pictured above). He added that the continuous and odd sound could be explained by reverberations around the stratosphere

Enthusiasts claim that such a supersonic or hypersonic plans could be what caused the strange noises at the weekend. In particular, an expert said the sound is similar to that created by pulse detonation engines. An artist's illustration of what the Aurora plane could look like is pictured

People described it as loud enough to shake their homes and rattle windows.

This has led conspiracy theorists to claim the power source could be behind a hypersonic US spy plane, dubbed Aurora.

Aurora is rumoured to be an ultra top secret aircraft that has been in development since 1989.

THE AURORA RUMOURS Aurora is rumoured to be a top secret aircraft that has been in development since 1989. It could be a successor to the Mach 3.35 Lockheed Martin SR-71 Blackbird craft that was retired in 1998. By comparison, extreme reports claim the Aurora could hit up to Mach 11.8. These claims originated in Aviation Week & Space Technology magazine, which ran an article in 1989 about a a mysterious entry in the 1985 US budget. The entry said $445 million was attributed to 'black aircraft production' under the name Aurora. These reports did not reference a single craft, instead they discussed a series of planes. Other reports suggest the Aurora programme kicked off at Lockheed Martin's Skunkworks in 1987. The firm was said to be looking into replacing its SR-71 Blackbird. In November 2013, Lockheed Martin announced it was developing for its SR-72 spy plane. It said the plane can accelerate up to Mach 6, or 4,567mph (7,349km/h) - three times faster than Concorde. Advertisement

It could be a successor to the Mach 3.35 Lockheed Martin SR-71 Blackbird craft that was retired in 1998.

By comparison, extreme reports claim the Aurora could hit up to Mach 11.8.

These claims originated in Aviation Week and Space Technology magazine, which ran an article in 1989 about a mysterious entry in the 1985 US budget.

The entry said $445 million was attributed to 'black aircraft production' under the name Aurora.

These reports did not reference a single craft, instead they discussed a series of planes.

Other reports suggest the Aurora programme kicked off at Lockheed Martin's Skunkworks in 1987.

The firm was said to be looking into replacing its SR-71 Blackbird, which was later retired in 1998.

However, the former head of Lockheed's Skunkworks division, Ben Rich, said Aurora was a codename for the stealth project which eventually led to the B-2 Spirit.

But, in November 2013, Lockheed Martin announced it was developing a spy plane with similar technologies called SR-72.

The firm said the plane can accelerate up to Mach 6, or 4,567mph (7,349km/h) - three times faster than Concorde.

Concorde flew no faster than Mach 2, primarily because the materials weren’t available in the Sixties that could withstand greater heat.

Technology has advanced since then, and the SR-72 will be a so-called ‘warm structure’ - it will heat up rather than reflect the heat using the sort of ceramic tiles that covered the Space Shuttle.

Concorde wasn’t allowed to fly supersonic over land because of the ‘sonic boom’ - the sound associated with the shockwaves created by a craft moving faster than the speed of sound.

Aurora is rumoured to be a top secret aircraft that has been in development since 1989. It could be a successor to the Mach 3.35 Lockheed Martin SR-71 Blackbird craft that was retired in 1998 (pictured). These claims originated in Aviation Week and Space Technology magazine in 1989

A PDE engine works by using force from a series of explosions, caused by mixing a fuel mist and air intake, to thrust itself forward. It can theoretically power planes at five times the speed of sound. A PDE can detonate between 60 and 100 times a second and its contrails appear to look like 'rings on a rope' (pictured), or a spine

According to experts, including Dr Phillip Atcliffe, senior lecturer in aeronautical engineering at Salford University, if a passenger jet flew at Mach 6 at current jet altitudes of around 30,000ft (9,144 metres), the sonic boom could damage buildings.

Officials routinely deny Aurora exists. But that has not dampened the spirits of the theorists, who point to a sighting of a mysterious triangular object by a North Sea oil engineer in August 1989.

Dr Khandelwal was keen to distance himself from the world of conspiracy theories, though he conceded there could always some things unknown to the public.

‘Of course we can’t know for sure if someone else could have the technology already,' he said.

Dr Khandelwal, is among a team of scientists working on the technology behind such types of 'pulse detonation engine'.

'It makes the same kind of pulsing sound as the one on this audio,' he told MailOnline.

WHAT WOULD AN AURORA PLANE LOOK LIKE? Speed: Speeds are reported to be in the range of Mach 5 to 8. Length: 110ft (33.5 metres) Wingspan: 60ft (18.2 metres) Engine: There are a number of possible engine technologies that have been linked to the Aurora project. In November 2013, Lockheed Martin announced it was developing for its SR-72 spy plane (pictured) said to be able to accelerate up to Mach 6 One in particular, which Dr Bhupendra Khandelwal an engineering research associate from Sheffield believes may have caused the booms heard over the UK and New York, is called a pulse detonation engine (PDE), or pulse detonation wave engine (PDWE). At regular speeds, the craft would be powered by a traditional jet engines built into the lower fuselage. Once it hits supersonic speed, the PDE takes over. A PDE works by sending liquid methane or liquid hydrogen into the engine. The fuel mist is then ignited. This detonation is made inside a specially designed chamber and occurs when the aircraft is travelling beyond the speed of sound. At these speeds, a 'thrust wall' is created. This is when the craft is travelling so fast, air is pushed near the nose that creates a 'wall'. When the detonation occurs, the aircraft's thrust wall is pushed forward, and this is repeated numerous times to propel the aircraft forward. Alternatively, pulsejets could compress the air caused as the craft travels forward to make it more streamline, while fuel is ignited in a combustion chamber. The pressure of the expanding gases in this chamber then propel the jet forward. Weapons: Rumours claim the Aurora may be equipped with air-to-ground weapons, but this would add weight to the craft, suggesting it is more likely that the plane would be used to reach destinations and reconnaissance missions instead. Advertisement

‘When we run a test engine it’s a real industrial noise and you can hear it for miles. We have people coming to us asking to make less noise or keep it to the daytime.'

A PDE engine works by using the force from a series of explosions, caused by mixing a fuel mist and air intake, to thrust itself forward. It can theoretically power planes at five times the speed of sound.

The technology builds upon 'pulsejet' principles which first emerged in the early 1900s and were used in German V-1 flying bombs.

Test flights using the most recent forms of the technology have lasted only a few seconds, but it is still listed by conspiracy theorists as a possible way of powering the so-called Aurora spy jet.

Concorde flew no faster than Mach 2, mainly because the materials weren’t available in the Sixties that could withstand greater heat. Technology has advanced, and the SR-72 (engine details pictured) will be a so-called ‘warm structure’ - that will heat up rather than reflect the heat

Steven Aftergood, a government secrecy expert at the Federation of American Scientists, said: 'If an aircraft is responsible, then it’s worth noting that it may not be local at all.

'Because the sound wave that causes the boom can be reflected by the stratosphere, the source of the event could conceivably be hundreds or thousands of miles away from the place where it is heard on the ground.'

But Dr Andrew Taylor, a senior lecturer in aviation at Buckinghamshire New University, said the noises did not sound like a normal sonic boom.

WHAT IS HYPERSONIC TRAVEL AND WHAT CAUSES THE SONIC BOOM? A supersonic plane is one that flies faster than the speed of sound, at Mach 1 or greater, using a jet engine. Mach 2.5 is about the speed limit for gas-turbine engines. Any faster and the temperature and pressure of air entering the engine is too high for the turbo machinery inside. To fly at hypersonic speed - Mach 5 and above - requires a different type of engine such as a supersonic-combustion ramjet, or scramjet. These engines have no moving parts. Instead of the rotating compressor and turbine in a jet engine, air is compressed and expanded by complex systems of shockwaves under the front of the aircraft, inside the inlet and under the fuselage at the rear. Travel becomes hypersonic when temperatures get so hot that air molecules become unstable and begin losing electrons. At these speeds the air becomes an electrically-charged field. At supersonic speeds, air moves through a series of channels until is slowed down to a point where fuel can be more easily injected and ignited. This releases energy and thrust. At hypersonic speed, this air moves even faster, which makes it difficult to slow down to the speed of sound and therefore requires specialist fuel and technologies, as seen in engines including the pulse detonation engine (PDE). Air reacts like a fluid to supersonic objects. As objects travel through the air, molecules are pushed aside with great force and this forms a shock wave much like a boat creates a bow wave. The width of the so-called boom 'carpet' beneath the aircraft is around one mile (1.6km) for each 1,000ft (304 metres) of altitude A PDE can make between 60 and 100 detonations a second. The sonic boom is created when an aircraft or other type of vehicle flies overhead faster than the speed of sound. Air reacts like a fluid to supersonic objects. As objects travel through the air, the air molecules are pushed aside with great force and this forms a shock wave much like a boat creates a bow wave. The bigger and heavier the aircraft, the more air it displaces. The width of the so-called boom 'carpet' beneath the aircraft is around one mile (1.6km) for every 100ft (30.5 metres) of altitude. An aircraft, for example, flying supersonic at 50,000ft (15,240 metres) can produce a sonic boom cone about 50 miles (80km) wide. 'Because the sound wave that causes the boom can be reflected by the stratosphere, the source of the event could conceivably be hundreds or thousands of miles away from the place where it is heard on the ground.' Steven Aftergood, Federation of American Scientists The sonic boom, however, doesn't sound the same at each point. The maximum intensity is heard directly beneath the aircraft, and this decreases as the lateral distance from the flight path increases until it ceases to exist because the shock waves refract away from the ground. The spread of the sonic boom depends only upon altitude, speed and the atmosphere - and is independent of the vehicle's shape, size, and weight. Although the speed at which it was travelling, and its location above the Atlantic could reduce this altitude and spread. Steven Aftergood, a government secrecy expert at the Federation of American Scientists, said: 'If an aircraft is responsible, then it’s worth noting that it may not be local at all. 'Because the sound wave that causes the boom can be reflected by the stratosphere, the source of the event could conceivably be hundreds or thousands of miles away from the place where it is heard on the ground.' But Dr Andrew Taylor, a senior lecturer in aviation at Buckinghamshire New University, said the noises did not sound like a normal sonic boom. Meanwhile, Professor Trevor Cox, an acoustic engineer from Salford University told MailOnline: 'To have heard a noise simultaneously in New York and the UK, the source of the sound must have been flying half way between. 'That's an awful long way - about 4,000 miles. You do get cases of sounds travelling a long way, for example, in 2005, sounds from the Buncefield fire travelled around 125 miles to Belgium. 'But in this instance, it sounds quite unlikely.' Advertisement

'With smaller fighter jets just a single boom would be heard, or, as with Concorde, a "double boom" might be heard from larger aircraft as both the nose and tail cause shock waves,' he said.

'It sounds like gunfire or other ammunition, similar to what I used to hear as a child growing up in Lincolnshire when the RAF and USAF aircraft used to do bombing runs on the east coast bombing ranges.

THE RACE FOR SUPERSONIC AND HYPERSONIC TRAVEL Scramjets have been under development for decades, but a breakthrough came in May 2013, when the U.S. Air Force Research Laboratory’s Boeing X-51A WaveRider flew for 240 seconds over the Pacific on scramjet power, reaching Mach 5.1 and running until its fuel was exhausted. Lockheed Martin's Skunk Works - builder of the Mach 3.5 SR-71 Blackbird spyplane - then unveiled plans to develop a successor, dubbed the SR-72, pictured The next step is to build a high-speed cruise missile, able to strike distant targets in minutes, not hours. Designed for reconnaissance and strike missions, the SR-72 would combine turbojet and ramjet/scramjet engines to enable the aircraft to take off from a runway, accelerate to a Mach 6 cruise, and then return to a conventional runway landing. If it can secure funding from the U.S. Defense Department, Lockheed Martin believes a prototype could be flying as soon as 2023 and the SR-72 could enter service by 2030, potentially paving the way for commercial applications of scramjet technology. Advertisement

'It could be geological or meteorological, but certainly not aeronautical in my opinion.'

Many Twitter users suspected sonic booms, similar to ones which shook Kent last month when two RAF jets intercepted a Latvian cargo plane in British airspace.

But a Ministry of Defence spokesman told MailOnline last night she had no records of any jets being scrambled.

Others suggested unusual weather conditions might be the source, but the Met Office dismissed those claims and said there was nothing out of the ordinary.

A spokesman told MailOnline: 'It definitely wasn't meteorological'.

The Metropolitan Police said there had been a fireworks display in Croydon, but Twitter users insisted that could not explain sounds in Bedfordshire, Glasgow, North Devon, Leicestershire and West Sussex.

At around the same time, a loud boom was reported by a number of people in the upstate New York areas of Buffalo, Cheektowaga and Clarence more than 3,000 miles away.

People described it as loud enough to shake their homes and rattle windows.

In the US, in particular, the boom was attributed to a micro-earthquake.

But Brian Baptie, seismologist at the British Geological Survey told MailOnline: 'Micro earthquakes are small.

'Usually too small for people to feel and it’s extremely unlikely that the noises were caused by this.

'Even small earthquakes some have audible phenomenon. For example, the Folkestone earthquake of 2007, that had a magnitude of 4.3, had a loud booming noise.

'This is because the vibrations travel through the ground, and when this is coupled with the atmosphere it generates sound waves that can be heard over a large distance.

'But, observing this noise across such a large distance, including across countries, is unlikely.

Many of the reports were picked up by Twitter user Virtual Astronomer (pictured), who said space debris re-entering the earth's atmosphere could have been responsible. He also said he was convinced the noises were created by aircraft sonic booms

One possible explanation is that the loud noise and ground shaking could have been a meteorite breaking up in the atmosphere, which would result in a sonic boom - but this was dismissed by another expert

'It’s a well-known phenomenon and happens for big earthquakes, but if this was the case it would have been felt as well, too, so it is unlikely the booms would just be down to an earthquake.'

Ms Angiletta, who recorded the sounds told MailOnline: 'I was just at home watching TV when I couldn't hear the program due to the loud noises. It was very distracting as it went on for ages.

'I went out to look for fireworks but I couldn't see anything in the sky. That's when I recorded the clip to send to my family to see if they could hear the same thing.'

The 27-year-old said that her family, who live roughly seven miles away in Norbury, south London, could also hear the sounds, which lasted for about 30 minutes. She then turned to Twitter to see if anyone could explain what they were.

If an aircraft is responsible, then it’s worth noting that it may not be local at all... The source of the event could conceivably be hundreds or thousands of miles away Steven Aftergood, Federation of American Scientists

Many of the reports were picked up by Twitter user Virtual Astronomer, who said space debris re-entering the earth's atmosphere could have been responsible.

'Space debris such as old satellites and things can cause sonic booms heard over very large areas,' he told MailOnline. 'It's the same for big meteors or rocks that come in.

'There was very little wind last night so conditions were perfect for sound to travel very long distances.'

Science writer David Dickinson was among the experts who dismissed the meteor theory.

He told MailOnline that there was one piece of debris from Russian satellite Kosmos 2251 scheduled for re-entry, but said that the timing was 'not a good fit' for it to have been over the UK.

He added: 'I do not think it was a meteor or a piece of space-junk, as the noises mentioned spanned a large segment of time. Plus, unless it was cloudy over the U.K., there would've been visual sightings.

Theories: There was no shortage of ideas when it came to the possible source of the noises

Dave Reed, who lives in Fareham, Hampshire, said his dogs 'went crazy for a couple of minutes' after hearing what he had assumed were fireworks.

The noises prompted conspiracy theories and immediate claims of a 'media blackout'.

Twitter user Carrie Proctor wrote: 'This is how we'll find our that WW3 has begun. It'll be a Twitter hashtag long before any official announcement!'

One MailOnline reader heard similar noises in Belgium.

Hyacinth Fahsi, who lives in Grimbergen, near Brussels, said the sound at 11pm local time - the same time as it was heard in Britain - woke his daughter and matched the recording in Croydon.

Describing the sound as 'repetitive explosions', he said: 'I first thought it was firework but it was different. Maybe thunder, but the sky was clear and I didn't see lightning, even far away.

'I wasn't thinking about it until my wife read your article.'