Spectacular and Awe-Inspiring, even NASA describes the remarkable image obtained by the Hubble Space Telescope in those words. And what we see in this image is the beautiful Crab Nebula, truly a superstar among former super stars of the heavens.
This photograph shows the aftermath of the death of a massive star. Astronomers call this event a supernova, the luminous evidence of the explosion of a large star. It occurred when the unceasing nuclear reactions taking place at its core ever since it first became a star, had consumed much of its mostly hydrogen mass. At that point, the sheer force of gravity finally overcame the outward pressure of the “burning” of the still remaining inner material, until it then collapsed upon itself.
From once being much greater in size than our own star, the Sun, it has collapsed to a super-dense mass, thereby acquiring a new astronomic name of neutron star, and is now only about 12 miles in diameter with a volume in which there is contained more matter in the form of densely packed neutrons than, for comparison, all the material that presently makes up our Sun. At the instant of the star’s collapse, an incredible “explosion” released such an immense amount of energy that it created a flash of light so bright that it outshone the light of its home galaxy, continuing to do so for several months as it slowly faded from view, while in that time expending as much energy perhaps, as the Sun can produce in 10 billion years.
At the same time, the force of the explosion ejected into space, at ultra high speed, the remaining outer gaseous layers of the former star, and that is what we now call the Crab Nebula. What we see are the remnants of the former star’s atmosphere that even centuries after its initial explosion, continue to spread outwards, having traveled in all directions to cover a distance of about 10 light years, an area and region of still immense energy of erratically speeding sub-atomic particles, x-rays, gamma rays, and other radiation, that provides the beautiful pattern that the Hubble has now pictured for us.
The occurrence of a supernova such as the Crab nebula is one of the most violent but not uncommon events in the universe, a universe that looks so unchanging and peaceful when one views the skies at night from earth but in reality it is a universe that encompasses an extremely violent domain.
If you know where to look in the night sky, the nebula can still be seen with the aid of a relatively small telescope where it would appear as a somewhat hazy patch of light, not easy to discern.
But somewhat amazingly, the supernova that created the Crab Nebula was first seen without a telescope and was famously recorded by astronomers in China almost a thousand years ago. It was a naked-eye sighting in 1054 AD, that when it first appeared was by far the brightest object in the night sky and continued to shine for almost two years during which time, at its peak, it was even visible during daytime for few weeks, carefully recorded and described in the records of the Chinese observers of the time.
In the western world, it was rediscovered in 1731 by an English amateur astronomer and has since been a major subject of interest and investigation. Between 6000 and 7500 light years distant from our solar system, the Crab Nebula is one of the strongest energy sources that can be observed and a great deal has been learned about it.
Astronomers monitor the characteristics of the light and radiation generated, measure the changes in brightness, analyze its spectrum, identify the presence of particular elements and their abundance, all of which provides significant information regarding the matter of which it was made.
All of which contribute to the broader knowledge of our ever changing and still mysterious and puzzling universe.
The Crab Nebula Image is a composite image assembled from 24 individual exposures taken with the NASA Hubble Space Telescope, Credit: NASA, ESA, J. Hester and A. Loll (Arizona State University)
