CATCHING CRABS Fireworks In The Sky

 

I love the fourth of July, what with the fireworks and the Sousa Marches.  But there is a tinge of sadness too, because the greatest firework display in the sky, at least over the last two millennium, occurred on the fourth of July in the year 1054, and was achieved at an unbelievable cost. On that date, the Chinese court astronomer Yang Wei-Te, was shocked to see a new star, what he called a guest star, blaze into existence, where no star had been visible before.

This new star was reddish-white. It had rays visible streaming from all four corners, and was four times brighter than Venus, which is normally the brightest object in the night sky, besides the moon. This guest star was so bright that it was visible during the day for over three weeks. 

After that it remained visible at night, although now yellow in color, for three years, until the middle of April, 1057. And then, according to the Chinese, who were using only their eyes to observe and record the universe, the “guest” faded into obscurity.

The Anasazi Indians of the American desert southwest also noticed the guest star, and recorded it in their rock art and pottery. It is recognized as the same guest star the Chinese saw because the Anasazi pictographs include the new star and the moon. And modern astronomers have calculated that on July 5, 1054, the crescent moon, as seen from North America, would have been just 2 degrees north of where the guest star was seen. Carbon-14 dating of the art indicates it was created about 1060, plus or minus fifteen years. Unfortunately there are no Anasazi left to confirm this story, and, for some reason, no Europeans saw the guest star.  Maybe it was cloudy in Europe.

The next time human eyes alighted on this guest star, they belonged to the cheerful English physician and astronomy nut John Bevis, who, in 1731, happened to be looking through a telescope in just the right direction. He had never heard of the Chinese guest star -  no European had. But John noted fuzzy “strings of gas and dust” in an empty patch of the constellation Taurus, to the right of the bull’s right horn.

The tip of that horn is in fact a bright star called Aldebaran, an Arabic name which means “the follower”, because Aldebaran seems to follow the Pleides across the sky. The Pleides are a bright point of light that forms the tip of the bull’s other horn. Blevis called his fuzzy patch “M1”, and noted it in a manuscript, complete with drawings that recorded its position in the sky. But John’s publisher went broke, and his book was never went into print.  And poor John died in 1771, when he fell off his telescope. And it looked for awhile as if the guest might escape further notice. in Europe.

But bits and pieces of John’s manuscript fell into the hands of Charles Messier, a French astronomer who was collecting material for his own star chart, published in 1774. Charles gave full credit for the original observations to poor John, and even used John’s designation of M1,, but it became known as “Messier 1”.

In 1847, another Englishman, the third Earl of Rosse, using a better telescope, drew his own images of John Blevis’ “M1” in Taurus, and decided that it was a nebula (Latin for “cloud”.) He sketched it looking like a crab’s claw. Later, when Rosse could afford a better telescope, he realized that M1 did not look like a crab, but the name stuck. And thus the guest star known as M1 in Taurus, more commonly became known as the Crab Nebula.

By the early 20th century it was known that the crab was expanding, at something on the order of half of the speed of light (which is about 186,000 miles. or 300,000 kilometers per second). But, of course, as fast as the speed of light is, it still takes light from the crab over 6,000 years to reach the earth, meaning the crab is 6,000 light years away. But people were only beginning to realize how amazing the crab actually was.

Late in the 1950’s a woman attending an open house in the University of Chicago’s telescope approached astronomer Elliot Moore, and told him that the crab appeared, to her, to be flashing. Elliot assured the woman that all stars seemed to twinkle, to which she insisted that as a pilot she knew what stars did, and this one was not twinkling. It was flashing. Elliot dismissed her story, but it turned out that the lady was right, and the astronomer was wrong.

On the night of 28 November, 1967 a Scottish Quaker and Cambridge graduate student named Jocelyn Bell Burnell was working with undergraduates when she noticed what she called “scuff” on her radio telescopes’s data printout, indicating a rhythmic, regular and unexpected radio signal. Over eight weeks her team, and her advisor Dr. Anthony Hewish, tried to eliminate all logical sources for this interference, and failed. 

That's way science works, you know. Not by discovering something, but by proving it can't be anything you already know about.  So, could this have been a Jodie Foster “Contact” moment?  As a joke, Joycelyn labeled her discovery LGM – 1, for Little Green Men, Source One. Eventually other similar sources of regularly pulsing radio waves were located, originating from other spots in the sky, and the joke was dropped. For practical reasons, the sources were renamed “pulsars”, because they seemed to pulse with energy. 

In 1974 Dr. Hewish was awarded a Nobel Prize for Jocelyn Bell Burnell’s discovery. She was not slighted because she was a woman, but because she was a graduate student. In 2018, as a consolation prize, they gave her $3 million dollars.

It was decided the year after Jocelyn’s discovery, that the pulsars were in fact, neutron stars. The star that exploded to create the guest star observed in the sky over China in 1054, started out 10 times the size of our sun. After its super nova explosion, what remained was a star, dead center of the crab, just 6 miles in diameter, rotating 30 times a second, or at roughly 4 million miles an hour. That spin creates a huge magnetic field, throwing out 100,000 times the energy thrown out by our own sun, all ripped from the atoms in the space surrounding the pulsar. 

The energy from the pulsar itself is emitted only in the higher energy parts of the spectrum, above the visual range. Seen by a radio telescope, and by folks with really, really good eyesight, the pulsar seems to blink on and off, 30 times a second. In fact it is not blinking, but like a light house beacon, it's emitted energy is confined by the neutron star's magnetic fields into narrow pathways, which sweep over our planet 30 times a second, from 6,000 light years away.

So it was, without a doubt, the biggest 4th of July fireworks display in human history, a crashing explosion of  light and an electromagnetic display on a galactic scale. The star that exploded here must have consumed an entire solar system, planets and moons and perhaps even life forms. The bomb must have gone off 6,000 years before the light ever reached us. The ice age was barely over. Humans had barely invented the wheel. We had not yet invented writing, even in China. But we would know, eventually, that the light reaching us from the Crab Nebula is emitted by photons passing through heavy elements like carbon, oxygen, nitrogen, and iron, all created out of hydrogen by that explosion.

Just think about that for a few seconds. The heavy elements giving color to the Crab Nebula, and to the 2,000 neutron stars now known in the universe, could only have been produced in a super nova explosion, like the one that was first seen on 4 July 1054.  And those are the heavy elements that make up….us.  And all living things - animals, plants, politicians, pond scum and astronomers, every where in the universe. Whether we know about them or not.

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