by One of the most spectacular celestial sights ever seen suddenly appeared in the northern night sky 450 years ago this month: a “new” star in the constellation Cassiopeia (the Queen). It was the brightest nova recorded in about 500 years and, to this day, remains one of only five known supernovae observed in Galaxy galaxy.
To get an idea of how dazzling this object was, step outside one night this week around 8 p.m. local time and look up into the north-northeast sky at the familiar zigzag line of five bright stars that make up the “W” of Cassiopeia. Then look south-southeast at the bright planet Zeus, shining like a silver beacon, and try to imagine what it would look like if you could somehow increase its brightness eightfold. Then turn back to see Cassiopeia. Try to visualize such a dazzling object in this region of the sky and you’ll get an idea of what this strange new star must have looked like to those living in the late 16th century.
On November 6, 1572, the German astronomer Wolfgang Schüler of Wittenberg was the first to observe the appearance of this new star next to the darker star in the center W of Cassiopeia.” other sky watchers.
Related: Night sky, November 2022: What you can see tonight [maps]
Seeing is believing
When this stellar object made its first appearance, it was probably no brighter than an ordinary star. But when it was spotted by a Danish astronomer and noble Tycho Brahe (1546-1601) on November 11, 1572, the star rivaled Jupiter in brightness and, on subsequent nights, became equal to Aphrodite at her most brilliant. Tycho himself probably stumbled across this dazzling object and actually stopped people in the street, pointed to the sky and asked them to verify what he was seeing.
From his own written account of his discovery, he noted the following, according to “Burnham’s Celestial Handbook, Volume 1 (opens in new tab):”
“On the eleventh day of November in the afternoon after sunset… I was contemplating the stars in a clear sky. […] I noticed that a new and unusual star, surpassing the others in brightness, shone almost directly above my head. and since I was a child perfectly familiar with all the stars in the sky, it was clear to me that there had never been any star in that place in the sky (opens in new tab), even the smallest, to say nothing of a star so distinct and bright as this. I was so amazed at this sight that I was not ashamed to doubt the reliability of my own eyes. But when I noticed that others, after having the place pointed out to them, could see that there really was a star there, I had no more doubts. A miracle indeed, a miracle that has not been seen before our time, in any age since the beginning of the world.”
For the next two weeks, the nova far outshone every star in the sky and could even be easily seen through the brightness of the blue daytime sky, suggesting that it may have briefly rivaled the brightness of Venus. As November drew to a close, the nova began to gradually fade, changing from a bright silver to a yellow, then orange, then reddish glow, before finally disappearing from view entirely in March 1574, after being visible to the naked eye for some 16 months old.
What did it mean?
Naturally, many people immediately thought of the Star of Bethlehem, seeing it as a sign placed in the heavens foretelling the second coming of Christ.
But Tycho rejected this interpretation and pointed out that the star described in the Book of Matthew was visible only to the Magi and therefore could not have been a heavenly body. Others speculate about the devastation it could bring. And he also seemed to throw a monkey wrench into the teachings of Aristotle, who, with his enormous authority, had asserted that the world of the stars was eternal and unchanging.
Where does it come from?
So, what could this strange star mean? For the rest of his life, Tycho was puzzled by the mystery. He went on to write a lengthy work, ‘De nova et nullius aevi memoria prius visa stella’, meaning ‘Concerning the star, new and never in anyone’s life or memory’. The new star was neither a planet nor a comet, because it remained in the same place as a background stars throughout its visibility. These measurements clearly showed that this strange celestial body was beyond moon, in the realm of the fixed stars. If it had been closer, Tycho would have detected a shift as it moved across the sky. Thus, he concluded that Aristotle was wrong. the stars were not immutable. Tycho advanced a theory that the star had probably formed as a condensation of the dark matter of the Milky Way, even pointing to a dark region from which such condensation could have occurred.
The Greek astronomer, geographer, and mathematician Hipparchus (190 BC-120 BC) had also recorded new stars, though none were as spectacularly bright as the one in 1572. “So perhaps,” Tycho mused, “ the matter of the Galaxy occasionally coagulates into a star.” But any such star must also fade quickly, “for anything that arises after the completion of Creation can only be transitory.”
Tycho’s account of changes in brightness and measurements of his position are a valuable record for modern researchers and scientists. in his honor, this amazing object is often called Tycho’s Star.
A colossal explosion
In Latin, such a star was referred to as “stella nova” or “new star”. Today, we still call this type of star a nova, although we know it is far from new. In fact, modern observations reveal that we are seeing the star explode. Some of these explosions are not very big, but others are catastrophic, changing the entire character of the star. Indeed, these stars are far from young. They are near the end of their lives and really should be called dying stars.
The internal temperatures of such stars can reach up to 5 billion degrees Fahrenheit (2.8 billion degrees Celsius), where nuclear fusion it makes elements as heavy as iron and finally results in a huge explosion — a supernova. Tycho’s supernova of 1572 was categorized as a type Ia (“Type one A”) supernova, occurring when white dwarf the star draws material from, or merges with, a nearby companion star until a violent explosion is triggered. The white dwarf disappears, sending its debris hurtling into space.
The smoking gun
For decades, the only remnants of the 1572 explosion were very faint patches of nebula visible only in large telescopes. Most of the residual debris cloud is completely invisible due to insufficient lighting. But in July 1999, the Chandra X-ray Observatory placed in Earth orbit by space shuttle Columbia. It is sensitive to X-ray sources 100 times fainter than any previous X-ray telescope, and when trained on Tycho’s supernova remnant, the finally the first light image was obtained. A solid object at the center of the remnant revealed a fascinating pattern of bright clusters and dense nodes and fainter regions — which could be neutron star or even a black hole.
The distance to Tycho’s star is estimated to be somewhere between 8,000 and 9,800 light years, which means that, at its peak, this exploding star had an actual luminosity of about 300 million times that of the sun! Such a star, within a few days, emits into space an amount of energy equal to its total production sun for several million years.
Repeat performance soon?
Will we ever have the opportunity to witness another stellar explosion similar to Tycho’s supernova in our lifetime? It can. In the last 1,000 years, only five supernovae (opens in new tab) have been observed and recorded in our galaxy: A very bright new star that appeared in the southern constellation Lycus (the Wolf) in AD 1006; a brilliant supernova that exploded in the constellation Taurus (the Taurus) in 1054 AD. one seen by Chinese astronomers (opens in new tab) in 1181; Tycho’s star in 1572. and a supernova in 1604 that was extensively studied by the German astronomer Johannes Kepler.
This suggests that we should expect a supernova to occur at intervals of about 250 years, on average, and based on that time frame, we’re long overdue for another one. And yet, twice we’ve had two supernovae occur within less than 50 years of each other, followed by a wait of more than 500 years until the next pair, again separated by less than 50 years. Moving into this strange time frame, we might not expect to see much more into the 22nd century.
However, no one can say for sure when the next supernova will light up our sky. It might be tonight, which is just as good a reason to keep looking up!
Joe Rao serves as an instructor and guest lecturer in New York Hayden Planetarium (opens in new tab). He writes about astronomy for Journal of Natural History (opens in new tab)The Rural Almanac (opens in new tab) and other publications. Follow us on Twitter @Spacedotcom (opens in new tab) and up Facebook (opens in new tab).
