Astronomical Guest Stars – A Historical Catalogue

Guest stars are supernova events. This is when an old star explodes, causing it to become rapidly and massively more bright. It usually then fades over the next 1-2 years.

If a supernova occurs in our own galaxy the “Milky Way”, it can be highly visible in our sky, sometimes even during daylight.

There have been a number of well-known, highly visible supernova events in the history of astronomy, although there has not been one for 400 years.

When they have occured, they have had great influence on astronomers and astronomical thinking, at that time.

Here is a brief catalogue of known, bright supernovae.

Year AD1006 in the constellation of Lupus

This would have been too low in the sky for the UK, but it was observed and recorded in China and also at St Gallen in Switzerland.

It was very bright – nearly as bright as the Moon – and lasted for over two years. The remnant is not visible optically today, but is detectable as the radio-wave source SN1006.

Year AD1054 in the constellation of Taurus

The remnant is visible today as the Crab Nebula. The exploding star reached magnitude -4 (as bright as Venus appears) and lasted for 21 months.

It was extensively observed and recorded in China, but strangely, there is NO confirmed record in Europe.

We may ask, why was this event ignored? Astronomers surely must have seen it?

It is suggested that to blame, could be the dominant doctrine on the perfection and unchanging nature of the universe, as decreed by Aristotle and Ptolemy a thousand years before. Astronomers were not willing to record what they saw, because it was clear evidence that the universe was not as was believed and they feared upsetting the authorities.

Year 1572 in the constellation of Cassiopeia

This was the supernova that was famously observed and measured by Tycho Brahe. It made his reputation as a great astronomer. It also touched him personally, writing that it was “a special creation of God”. Tycho’s personal notes still exist in a museum in Copenhagen.

It was as bright as Venus (about mag-4), but by May 1573 has faded to magnitude 2. Today, its remnants may be found in the optical and radio spectra.

Year 1604 in the constellation of Ophiuchus

This supernova is often known as the “Kepler Star”, not because Kepler discovered it, but because he observed, measured and recorded it as part of his official work.

It was like as bright as Venus, like the one of 1572, just 32 years before. But particularly striking, would have been its proximity to both Jupiter and Saturn, at that time. A remarkable sight!

When will the next “guest star” appear in our galaxy?

Who knows? Certainly not me. But 400 years have passed since the last nearby star explosion.

And we have recently detected hundreds of supernovae in other galaxies.

So perhaps it will not be too long to wait?