Monday, November 26, 2012

The End of the World in 2012? An Astronomer’s Evidence

Professor Dame Jocelyn Bell-Burnell FRS, centre in the photograph, spoke on the above topic at our London Centre on 15 February.
Imagine ten months from now, it is the morning of the 21st December the last Friday before Christmas, schools are breaking up and people are frantically doing their last minute shopping. 
The clock turns to 11:11 it does not turn to 11:12 because the World has been destroyed and we are all dead! Many people believe this will actually happen, in fact an industry has sprung up publishing books and releasing a blockbuster film to cash in on this ‘prophesy’. 
If there is the remotest chance that such a catastrophe could occur then why are crisis meetings not being held at the UN? Why are underground shelters not being excavated under mountain ranges? 
Why are food, fuel and medicines not being stockpiled? Why are survival colonies not being constructed in orbit or on the Moon? The answer is simple: It is all complete nonsense!

On 15 February the branch was fortunate enough to have Professor Dame Jocelyn Bell-Burnell speak to a packed Rutherford lecture theatre about this so-called prophesy of doom. 

Her lecture came about because while lecturing in the United States somebody would always ask her ‘Is the World going to end in 2012?’ Being a responsible scientist she decided to research the subject.
It all has to do with an ancient civilisation called the Maya that flourished in what is now Mexico in the two millennia before Christ. They were accomplished mathematicians and astronomers. They produced calendars that spanned long periods of time. 

Their last calendar which started on 11 August 3114 BC will end on 21 December 2012 AD. Some people have speculated that the Maya did not extend their calendar beyond this date because they somehow ‘knew’ the World would end on that day - that’s it!
Dame Jocelyn made it very clear that there is no historical or archaeological evidence that the Maya intended the end of their calendar to mark the end of the world. 

She believes the Maya would have treated it in the same way we celebrated Millennium Night - with a party and a day off! She believes 11:11 AM 21st December 2012 was chosen because it is the northern hemisphere winter solstice when the Earth is at full tilt and the Sun is at its lowest point in the sky. 
This makes sense, a precise astronomical event that you can use to start the next calendar. The Mayan calendars were also inscribed in stone, they may simply have not had a rock big enough to go further into the future!

As the calendar ends with an astronomical event Dame Jocelyn decided to survey geophysical and astronomical threats that could befall the Earth. These include:
  • Geomagnetic Field Reversals
  • Solar Storms
  • Asteroid Impact
  • The planet Nibiru
  • Planetary alignments perturbing the Earth’s orbit
There is evidence that in the past the direction of the Earth’s magnetic field has changed direction - flipped. Towing a magnetometer across the Atlantic sea floor has revealed mirror images of alternating directions of magnetisation either side of the mid-Atlantic ridge. A crustal construction zone, magma swells up and spreads creating new sea floor. As the magma cools and solidifies it is magnetised by the geomagnetic field leaving a record in the rock of the direction of the Earth’s magnetic field. 

From this we see that the geomagnetic field reverses on average every 300,000 years (the last was 750,000 years ago so we are well overdue). Many living things, including birds, can sense the geomagnetic field and use it for navigation. 

They would obviously be affected by a reversal but a flip does not occur overnight, it takes about 5,000 years to complete, giving animals time to adapt. As Dame Jocelyn points out, there have been eleven reversals since our tool making ancestors H.habilis evolved two and a half million years ago - and we are still here!

Our Sun also has a magnetic field which periodically reverses but despite being a much more massive body a solar field reversal occurs in much less time. 
The interval between maxima (when the Sun’s magnetic field is at full strength) is approximately eleven years. Maxima are also when sunspots and solar storms are most numerous. A solar storm is a jet of protons and electrons emitted from the Sun. 

When these particles strike the upper atmosphere they give rise to beautiful auroras. The last maxima was in the year 2000 the next will be in 2013 (not 2012). Dame Jocelyn reminded us that a solar storm has never killed anybody or caused a building to collapse although they can disable satellites and we are now more dependant on satellite services such as GPS. She produced a chart of number of sunspots against date. 
The peaks corresponding to maxima were very clear but also noticeable was that the peaks were in groups of lower and higher amplitude. It is predicted the 2013 maxima will be the lowest in a hundred years.
A threat we are very familiar with is asteroid impact. A massive impact 65 million years ago is believed to have caused an extinction event that wiped out the dinosaurs. Dame Jocelyn produced an image of Barringer crater in Arizona. 

This mile wide crater is believed to have been made by an object 50 metres in diameter. The object that exterminated the dinosaurs is believed to have been a kilometre across. The Earth is struck by an asteroid this size every 50 to 100 million years so again we are due for another impact.
Last October a small asteroid passed between the Earth and the Moon. Around the globe several telescopes are dedicated to Near Earth Object Monitoring. 

The speaker showed a photograph of the Pan Starrs telescopes under construction in Hawaii which will scan the night sky for objects under 200m in diameter that come close to the Earth. 
Interestingly Dame Jocelyn stated that the technology to deflect an asteroid is already available. She said the worst thing we could do is to try and blow it up using a nuclear weapon - a la Bruce Willis - this would create millions of objects to track. 

A better way is to coat the object with a white deposit or erect a solar sail on it and use the radiation pressure of sunlight to push it out of harm’s way. The only NEO astronomers are concerned about is an asteroid called 1950DA which will come uncomfortably close to the Earth in 2880. Nibiru is a planet that was supposed to have been discovered by the ancient Sumerians about 2500 BC. The pseudo-science community have suggested this planet will collide with the Earth in December. There are many problems with Nibiru: Why did not other stargazing civilisations such as the Mesopotamians, Babylonians and the Chinese also discover it? Nibiru is said to have an orbital period of 3600 years (Pluto 248 years) this means it has a very large orbit but to collide with the Earth its perihelion point must lie inside the Earth’s orbit. This can only come about if Nibiru’s orbit is unbelievably eccentric. At the time of ‘discovery’ Nibiru would have been ten times the distance to Pluto against a very crowded starfield background. 

Assuming the Sumerians had not discovered the telescope then to be a naked eye object at that distance Nibiru would have to be 150 times the size of the Sun and have a mass of 3.3 million Solar masses - we are not taking about a planet! Dame Jocelyn did mention the possibility that Nibiru could be a brown dwarf - a star that did not quite make it. 
The Sun is unusual in that it is solitary, most stars are in multiple star-systems. Our nearest stellar neighbour, proxima centauri, is part of a trinary star system. However a brown dwarf would be a daylight object even at four astronomical units.

Occasionally the planets line up in what is called a conjunction where they can all be seen in a small area of sky. Venus and Jupiter will be in conjunction on the 13th of March. 
Could the combined gravitational pull of the other planets pull the Earth into a different orbit? The speaker produced a pie chart showing the relative gravitational influence of the other bodies on the Earth. Nearly all the chart was due to the Sun with a thin sector representing the Moon. 

The combined contribution of the other planets is one two hundredths of the Moon and could not be seen on this scale. In 2000 five planets and the Sun where in conjunction with the Earth. In 1962 five planets, the Sun and the Moon were in conjunction. There are no major conjunctions in 2012. At the centre of all galaxies lies a monster - a supermassive black hole. The speaker showed a clip of stars orbiting an invisible object at the centre of our galaxy. It can be viewed below:


One star can be seen to describe a complete orbit. Another star, designated SO-45, moves in a straight line. When asked about this Dame Jocelyn suggested its orbital plane is edge-on to our line of sight.  Could an alignment of the Sun and the black hole at the centre of the Milky Way throw the Earth out of the Solar System? Coincidentally the Sun and Black Hole are in conjunction on the 21st December. As supermassive black holes go the one at the centre of our galaxy is a tiddler, weighing in at a mere four million solar masses. 
The galactic centre is also 26000 light years away. In short the gravitational pull of the Sun on the Earth is one hundred billion times stronger than the black hole.

Surprisingly the one threat the discoverer of pulsars did not discuss was supernovae. The red supergiant Betelgeuse is regarded as a potential supernova and astronomers have recently noticed an unusual variation in its light curve indicating it is becoming unstable. Fortunately it is 640 light years away so when it does go off we will get an impressive light show but no damage.

Dame Jocelyn concluded her lecture by asking what was going on? Why do so many people choose to believe in the most fantastic, unsubstantiated theories? As she says we are not rational beings. 
She showed us one of her favourite websites www.manyendings.com. This site lists doom prophecies that were going around in various years and there are a surprising number of them. In 1954 a cult predicted the end of the World. 

The American psychologist Leon Festinger used his graduate students to infiltrate the cult in order to study them. They patiently waited for the appointed hour and waited and waited and waited until at two in the morning the cult leader announced he had received a revelation that God was so happy with the devotion of the group he had decided to postpone the apocalypse! To the psychologists surprise this did not undermine the faith of the cultists, the opposite happened, it reinforced it! 

This was a laughable example of cults others have been very tragic. In 1997 comet Hale-Bopp was visible from Earth, a UFO cult in California believed a spacecraft was in the tail that would take them to a new planet but they would first have to surrender all their worldly possessions including their bodies. Police later found the remains of 39 cult members. Dame Jocelyn reminded us the Internet can be used to disseminate misinformation. One site, belonging to the ‘Institute of Human Continuity’ makes several references to the Columbia Pictures film ‘2012’ and is believed to be a subtle form of advertising for the film. 

The speaker said one way you could recognise it was not an academic site is that it is too professional! 
She recommended people should receive their information from real academic sites such as iop.org and look for sites ending in .ac.uk and .edu. Finally Dame Jocelyn said that to stop people believing in doom prophesies we must improve our teaching and communication of science. So don’t use the Maya as an excuse for not doing Christmas this year, get the turkey on order!

No comments: