Astronomy Cast- Giovanni Cassini.

Cassini was an Italian astronomer that dedicated most of his life to discovering most of Saturn's moons. The space probe cassini was also sent to further examinate the Saturnian moons. He was born in 1625, and so he was growing up learning about all these things going on, but he got to follow far enough behind them that he had much better optics to play with. Cassini got his PhD at age 25, and he had this interesting joint career where he was working in Bologna. he also made huge contributions in the fields of Mathematics and Physics. He was the first one to realize that Saturn's rings had divisions in them. He also discovered the rate of rotation of the planet Jupiter. Cassini was also very precise with his calculations. he tried to write down everything at the exact time of him noticing it.

Astronomy cast- Craters

There are many moons in the galaxy and on every moon there are tons of craters! There are several different names for the rocks that hit the planets and leave these imprints. Chondrites are the most common and they are basically iron meteors that crash on the surface of a planet and leave a crater. The angle of impacts affects what direction the ejecta travels. This is the cloud of material that gets thrown out of the ground and spewed in different directions. The shape of the crater depends on how the material from the initial impacts rises and later settles on the surface again. This is also affected by the angle of impact. For this reason there are many craters that have rings from the center to the outer part of the crater. You end up with craters that have neat layers layered through them with all sorts of different morphologies depending on where you hit. Craters are fascinating as they can carry substance from a planet from a very far place.

Astronomy Cast- Christian Huygens

Christiaan Huygens came from an important Dutch family. Tutored at home by private teachers until he was 16 years old, Christiaan learned geometry, how to make mechanical models and social skills such as playing the lute. Christiaan Huygens studied law and mathematics at the University of Leiden from 1645 until 1647. Van Schooten tutored him in mathematics while he was in Leiden. From 1647 until 1649 he continued to study law and mathematics but now at the College of Orange at Breda. He solved the related problem of how to hang weights on the rope so that it hung in a parabolic shape. Huygens soon turned his attention to lens grinding and telescope construction. Around 1654 he devised a new and better way of grinding and polishing lenses. Using one of his own lenses, Huygens detected, in 1655, the first moon of Saturn. The following year he discovered the true shape of the rings of Saturn. Huygens explained the phases and changes in the shape of the ring. Work in astronomy required accurate timekeeping and this prompted Huygens to tackle this problem. In 1656 he patented the first pendulum clock, which greatly increased the accuracy of time measurement. His work on the pendulum was related to other mathematical work. He was a great astronomer and mathematician of his time.

Astromomy Cast: The Milky Way

Milky Way is actually derived from a Latin term. It basically comes from the fact that there is this band of light that to the naked eye is perceived as this light patch, this illuminated patch that spreads in an arc across the sky. The Milky Way is that unusual band that crops up in the sky in dark locations. It literally looked like someone had spilled milk across the sky and that’s where the name came from. Galileo first paid attention to the milky way in 1610 when he observed the entire sky and all he could see was an infinite amount of stars.  It comes up higher in the north and lower in the south so there is this ring of light that essentially goes all the way around the Solar System.  William Herschel tried to map out the shape of the Milky Way. He counted stars in all the directions and drew a diagram and he thought that the Solar System was in the center of the Milky Way. There are bunches of stars that in groups that are called Globular Clusters. Instruments that help observe the Milky way are the Radio and infrared telescopes. They help pick out stars that are orbiting super-massive black holes. This is also why you can see more stars toward the center of the galaxy as opposed to the outskirts.

APOD 2.8

This is a huge bright apparition in the southern hemisphere. The tail of this comet lovejoy appears to be fading across the entire celestial pole. This picture was taken in Victoria Australia where the sky was covered with stars. This comet can be easily identified in the Milky way and there are several bright stars next to it. 2 important stars are Canopus and Sirius.

Biography Pierre Mechain

    Pierre Méchain was born August 16, 1744 in Laon, France. He was the son of Pierre-François Méchain, who was an architect, and Marie-Marguerite Roze, and early in his life wanted to follow his father in a career in architecture. He studied mathematics and physics, but due to financial difficulties he ended up leaving college. He then became friends with Jérôme de Lalande, who allowed him to proof-read parts of the second edition of his book, L'Astronomie.  This landed him a job as an assistant hydrographer at the Depot of Maps and Charts of the Navy in Versailles.  Pierre Méchain’s fame as an astronomer would not have started if it had not been for becoming friends in 1774 with one of his fellow co-workers, Charles Messier. The two astronomers worked together to discover deep sky objects and cataloged them in Messier’s catalog. Méchain discovered two comets in 1781 and was able to calculate their orbits. With these same calculations he was able to prove that the comets discovered in 1532 and 1661 were actually two different comets.

In 1777, Méchain married Barbe-Thérèse Marjou whom he met while working in Versailles. They had two sons: Jérôme, and Augustin. After his intrigue in the study of comets and other space objects, Mechain made at least 30 considerable deep sky objects that were most likely nebulous compounds. He made 26 of these discoveries between 1779 and 1782.  His most famous comet discovery was of Comet Encke in 1786. It is the comet with the shortest period ever discovered. He discovered the Sunflower Galaxy, the Phantom Galaxy, the Spiral Galaxy M77, the Pinwheel Galaxy, and the Coma Pinwheel Galaxy. These are included in Messier’s catalog along with M72, M75, M78, M79, M85, M94, M95, M96. However after all these discoveries some of them were received with controversies, mostly because of other astronomers asking for credit in discovering these sky objects.  Méchain disclaimed his discovery of M102 as an erroneous re-observation of M101, thereby initiating a still open discussion on the true founder of this object. He is also accredited with discovering M104, M105, M106, M107.  He sent them to Bernoulli, the editor of the Berliner Astronomisches Jahrbuch at the time. Since these four objects were not contained in the original Messier catalog, they were attributed separately to Pierre Méchain, John Herschel, and J.L.E. Dreyer.

After Mechain announced to the public his discoveries he later dedicated his life to other astronomical discoveries.  In 1787, Méchain collaborated with J.D. Cassini and Legendre on measuring the accurate longitude difference between Paris and Greenwich. In 1791, Méchain undertook the southern part of a new survey of the meridian from Dunkirk to Barcelona, together with an assistant, Tranchot. However much of his work was impeded by the french revolution. He and his partner got arrested in Essone.  Pierre returned home and became a member of the new Academy of Science and the Bureau of Longitudes. He was unsatisfied with his work for finding the meridian, so he left Paris but died in 1804 after catching yellow fever.



APOD 2.7

 Astronaut McCandleless, in this picture is floating free in space guided by a manned manuevering unit(MMU). Astronauts McCandleless and Robert Stewart were the first to experience a nontethered free float in space. This is the farthest out any astronaut in history has ever gone. MMU has been put to use by deploying space probes and satelites. They work by shooting jets of nitrogen. Compared to the amount of weight on earth these jet packs are virtually weightless in outer space. there have been many upgrades to this jetpack that make them easier to use.

Biography Sources

1999, and provisionally. "Pierre Méchain (1744-1804)." SEDS Messier Database. N.p., n.d. Web. 9 Jan. 2012. http://messier.seds.org/xtra/history/pmechain.html.

 

"Mechain biography." GAP System for Computational Discrete Algebra. N.p., n.d. Web. 9 Jan. 2012. http://www.gap-system.org/~history/Biographies/Mechain.html.