Stargazers | Supernova explosion: A celestial fireworks display
It was exactly 962 years ago that ancient stargazers watched one of the most dramatic celestial events ever: a supernova explosion. Today, nearly a full millennium later, we can still see the remnant of these remarkable celestial fireworks, even with just a small backyard telescope.
It was during the cool pre-dawn hours on July 4, 1054, that Chinese sky watchers marveled at what they saw in the constellation Taurus and recorded their observations for future generations to read. Paraphrased in English, it went something like this:
"In the first year, fifth month of the rule of Chih-ho, a 'guest' star appeared in the morning a short distance from T'ien-kuen. It had an iridescent glow — the color of emperors. It was visible in the daylight, like Venus, for twenty-three days."
Imagine that, a new star visible in full daylight! It was surely a most remarkable sight.
For three weeks this "guest" star outshined everything else in the sky. Then it slowly faded from view. Where it came from — and where it went — no one knew, so they believed they had witnessed the birth of a star. Why not? It appeared out of nowhere as if it had just been born.
Today, a casual glance toward this region of Taurus shows nothing unusual. But aim a telescope in that direction and you'll be amazed by what you see.
Comet hunter Charles Messier did just that back in 1758, and, while he wasn't interested in studying this object, he included it as the first line in his now-famous list known as the Messier Catalogue. M1, as astronomers now call it, is also known as the Crab Nebula because, when seen through a small telescope, it takes on the shape of the familiar crustacean.
Over the years, astronomers have learned that M1 is actually the remnant of a supermassive star that — during its final stages of life — tore itself asunder in a spectacular supernova explosion. In other words, what the Chinese saw on that July morning was not a star being born but a star dying.
We now know that the heart of this nebula harbors the tiny, dense corpse of the original star, now crushed into what we call a "neutron star," which spins 33 times every second and emits bursts of light in our direction with each rotation. It is this apparent pulsing that led astronomers to coin the term "pulsar."
To see the Crab Nebula for yourself you'll need a backyard telescope (the bigger, the better, of course) and a dark sky far from city lights. Just before dawn, aim your scope in the direction of the star that defines the tip of the bull's easternmost horn, then raise the scope up about one degree. The Crab — which is rather tiny — should appear as a very faint smudge in your field of view. Your best view will come later in the summer when Taurus and M1 appear much higher in the pre-dawn sky.
While you're enjoying the fireworks this July Fourth to celebrate the birth of our nation, think back to when ancient sky watchers unknowingly witnessed the truly shocking celestial fireworks of a violently dying sun.
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