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Founded January 1970
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"Tourists are fleeing the state by the tens of thousands. Now that Maine has lost its summer population, the wait times in stores, in traffic and at other public places will be greatly reduced. Does this mean that every September, Maine experiences rapid wait loss?"
THE DAILY ASTRONOMER
Tuesday, September 6, 2016
The First Messier
The year 2017 marks the 200th anniversary of the death of French astronomer Charles Messier (1730-1817), an avid comet hunter who, ironically, is best known for having compiled a catalog of celestial objects that resemble comets, but aren't. We still refer to this compilation as the "Messier Catalog,"and the bodies listed within it are known as "Messier objects." During the 2016-2017 DA school year, we will individually examine all 110 Messier objects. Sometimes, we'll devote an entire article to one of them. At other times, they'll appear on the "obverse side," of the DA,* tucked away in a footnote or featured in "From the Catacombs of Infinite Knowledge." If we devoted a DA to each Messier (if you know the proper pronunciation of his last name, you'll know that clause rhymes), we'd relegate about half the school year to this catalog. And, as you know, we are trying to divert a Pacific Ocean's worth of information into our own small burbling forest stream, so we have to prioritize.
The catalog's inception dates back to 1757 when the young French astronomer Charles Messier was working as a draftsman under astronomer Joseph-Nicolas Delisle. Delisle hired Messier to record astronomical observations and to search for Halley's Comet, which Halley had predicted would return to Earth's skies in in 1758/1759.** As Messier conducted his search, he spotted a strange sight that appeared comet-like but didn't change it position from night to night. Although they don't swoop through the sky like meteors, as often thought, comets do exhibit some motion over the course of successive evenings. The object Messier observed appeared immovable relative to the background stars. It turned out that it wasn't a comet at all, but a "nebula," a term applied to many celestial objects which were also-cloud like in appearance. The word "nebula" derives from the Latin word for "cloud"
French astronomer Charles Messier (1730 - 1817). Although
he considered himself a comet hunter, he is principally
known for having compiled a catalog of celestial objects that
resemble comets. (Painting by Nicolas Ansiaume)
Finding an astronomical object that bore such a close resemblance to a comet induced Messier to begin a catalog of these objects, for his benefit and for others. He chose the body in the constellation Taurus as his first entry and labeled it, appropriately enough, M1. We know of M1 as the Crab Nebula,a supernova remnant. Messier didn't actually discover this nebula, as it had previously been observed by German astronomer John Bevis (1695-1771). (See "From the Catacombs of Infinite Knowledge.")
Throughout the subsequent years, Messier added many entries to his catalog. The second, M2, was a globular cluster in Aquarius which another astronomer had also previously observed. He did discover his third listed object, (M3), a globular cluster in Canes Venatici. He would go onto add 110 objects altogether, 42 of which he discovered.
Today, we officially begin our year long tour of all these Messiers with the very first of them all, M1: The Crab Nebula
As we can see from the above star chart, M1 is tucked away just north of tau Tauri. This nebula is all that remains of a massive star that went supernova more than 7500 years ago. As this star was located about 6500 light years from our solar system, the explosion was recorded in AD 1054. The brilliant "star" was recorded by astronomers around the world, most notably in the Americas and China. The Crab Nebula -named by Lord Rosse as the filaments are reminiscent of crab legs- is a heavy element rich field of material 11 light years in diameter. The material is expanding at 1,500 kilometers per second, propelled by the ultra-powerful supernova.
The Crab Nebula (M1): a supernova remnant in Taurus the Bull. This nebula was the first object that Charles Messier recorded in the Messier catalog. We are seeing a rapidly expanding cloud of material expelled by a supernova. It currently spans 11 light years and grows at 1,500 kilometers per second. Image: The Hubble Space Telescope.
Supernovae explosions serve two important roles in our galaxy. They create all the elements heavier than iron and disperse this metal rich material through the galaxy. Our own solar system formed after material from a supernova mixed with a gas dust cloud. This collision precipitated a collapse and subsequent formation of myriad stars within a cluster. One of these stars was the Sun, around which the planets formed. By observing the Crab Nebula,we might well be seeing the progenitor of innumerable star clusters and associated planetary systems that will populate the galaxy in the distant future.
Our cosmos shows itself to be quite adept at recycling.
*Another feature we're adding is the 'Daily Astronomer Obverse Side," or DAOS: a side b that we'll tack onto a DA now and then. This DAOS will contain the more information, short stories,quirky conversations,and other extraneous material. More information later.
**Edmond Halley realized that the comet which now bears his name made repeated visits to the inner solar system throughout recorded human history and, being a solar system object, was destined to return multiple times. Halley predicted this comet would appear again in 1759, following its 1682 apparition. Halley died in 1742 and therefore didn't live to see its return. Messier was the first professional astronomer to see Halley's Comet when it returned in January 1759.
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FROM THE CATACOMBS OF INFINITE KNOWLEDGE:
John Bevis: Sighting a planetary rarity
John Bevis: Sighting a planetary rarity
John Bevis,a German physician and astronomer, is not exactly a household name, even among astronomers. However, Bevis has done something that nobody else has done. He is the only human to have telescopically observed a planet-planet occultation. On May 28, 1737 he watched an occultation of Mercury by Venus. (An occultation is the direct passage of one body in front of another.) In January 1818, Venus occulted Jupiter, but both bodies were too close to the Sun for safe viewing. The next planet-planet occultation will occur on November 22, 2065, when Venus again occults Jupiter. (Mercury occults Neptune two years later.) On November 22, 2065, many people will most assuredly observe a planet-planet occultation through telescopes. Until that time, astronomer John Bevis will be the only human to ever witness such an occultation through a telescope.
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