APOD 2.1

This week, I am looking at "Ultraviolet Andromeda" (October 27, 2010).

This picture is the highest resolution image ever made of the Andromeda Galaxy at ultraviolet wavelengths. It was taken by NASA's satellite, Swift. Swift is usually used to search for distant cosmic explosions. But with the 330 images that it took from May 25-July 26, 2008, it was able to form this amazing image. Using those pictures, an undergrad student at the University of Maryland at College Park who worked with Stefan Immler, a research scientist on the Swift team, was able to process all of that data to make the image that is seen here after 10 weeks of hard work. In this mosaic, it reveals about 20,000 ultraviolet sources in the Andromeda Galaxy, especially hot, young stars and dense star clusters. Studies show that tides raised by the many small satellite galaxies in orbit around M31 help increase interactions withing gas clouds that makes all of these new stars.

I really like this picture because it shows the entire galaxy and when you move your cursor over the picture, you can see the same galaxy in optical light. Compared with the image in optical light, the ultraviolet image appeals more to me just because it's purple. It has more of a fantasy look about it and the ring around it is more defined. But the optical image has more glare from the center and a white haze around the stars so it's a little harder to see them. I was also amazed that this picture was made out of 330 images put together. It turned out very nice and you can get an idea of how wide it actually is by the length of the picture (220,000 light-years across).

APOD 1.8

Vista with NGC 2170 (October 15, 2010)

This picture of the day is in the constellation Monoceros. The picture was taken by VISTA (a survey telescope) in near-infrared light.. It shows the bright stars surrounding  the dust and clouds which is where star formation and other young stars are hidden from view. This was interesting because I wasn't sure exactly what a Monoceros was. I thought it was some terrifying Greek mythological creature, but this constellation is actually modern. I learned that a monoceros was associated with a unicorn and had probably come from descriptions of a rhinoceros. I usually knew where most of the constellation's names came from but this was one of the few that I was unsure of, so it was interesting to read about the origin of it's name and what it was. This picture also relates very well to the chapter on telescopes that we just read in class. Seeing a video of the comparison between pictures taken with visible and infrared light gave me a better sense of why astronomers would want to study space in the different spectrums. The pictures that were taken in visible light had a lot of glare and twinkling from the stars. The colors weren't very bright either. With the infrared picture, the glare was greatly reduced so it was easier to get a view of the background and the star-forming region could be seen as orange/red with the colorful streaks coming out. This made me realize what a difference the sectrum made.

Observation 4

Date: Thursday, October 14, 2010
Location: My driveway in Osprey
Time: 9:10 PM

During this observation, the weather was very clear with few clouds. I saw the summer triangle directly above me. I also saw the moon in the east. It was a very bright half moon.

APOD 1.7

Moonquakes Suprisingly Common (Oct. 10, 2010)

This picture shows Buzz Aldrin standing on the moon next to a lunar seismometer. Apparently moonquakes, which are similar to earthquakes, are very common on the moon. Over the five years from 1972-1977, there have been a recorded 28 moonquakes. There are typically four types of moonquakes: deep moonquakes, vibrations, thermal quakes, and shallow moonquakes. The deep moonquakes occur 700 km below the surface and are probably caused by tides. The vibrations are caused by the impacts from meteorites. The thermal quakes are caused when the crust expands because of the sun after two weeks of deep freeze lunar nights. Shallow moonquakes are usually 20-30 km below the surface. I thought that the first 3 were major ones, but it turns out that the shallow moonquakes are actually more serious than the previous 3. This is because the shallow moonquakes tend to last longer. They describe it like hitting a tuning fork. It will keep going on and on. It usually lasts for 10 min compared to the half a minute quakes that we feel on Earth. It is amazing that the quakes can last this long. I wasn't even aware that the moon had quakes. From the typical pictures we see of the moon, the moon looks so peaceful and quiet. I was suprised to know that the moon had some similar quakes as we do on Earth and how intense they can really be. I have been through earthquakes that have lasted several seconds, I can't imagine enduring a 10 min one.

Biography of James Gregory (1638-1675)

James Gregory was a Scottish mathematician and astronomer. He was born near Aberdeen, Scotland in November 1638. He was the youngest son of John Gregory, a minister, and Janet Anderson. As a child he was introduced to geometry by his mother. After his father's death in 1651, his oldest brother, David, sent him to Aberdeen for grammar school, and eventually he would later attend Marischal College there. Encouraged by his brother, who was also mathematics fanatic, James dedicated himself to studying mathematical optics and astronomy.

In 1662, looking for more scientific opportunities, he decided to travel to London. There in London he would publish Optica promota a year later. In this book, he describes the first practical reflecting telescope, which was one of his big contributions to astronomy. Now called the Gregorian telescope, it was revolutionary because it used a combination of mirrors and lenses which made it more effective than previous telescopes using just lenses or just mirrors. Not actually able to built the telescope himself he tried to hire Reive, the leading optician, to build it for him. Unsatisfied, he gave up on the idea of building it. It would successfully be built ten years later by Hooke, who heard of Reive’s failed attempt. Optica promota would eventually earn him some influential friends including Robert Moray, interim president of the Royal Society in 1660.

Continuing to gain scientific knowledge, Gregory then traveled to Italy to study geometry, mechanics, and astronomy under Stefano degli Angeli in Padua. There he would publish two more works, Vera circuli et hyperbolae quadratura (1667) and Geometriae pars universalis (1668). Geometriae pars universalis is really the first attempt to write a text-book on what we would eventually call calculus. After publishing these he returned to London, where he was elected to the Royal Society despite implications from Huygens that Gregory had stole his results and published them in Vera criculi et hyperbolai quadratura as his own. Gregory then published Exercitaiones Geometricai to rebut Huygens.

In late 1668, Gregory presented some of his papers to the Society on various topics including astronomy, gravitation, and mechanics. Most likely with Moray’s influence in the society, Charles II was persuaded to make the Regius Chair of Mathematics so Gregory could continue his mathematical research. He was nominated to this new chair of mathematics at St. Andrews in Scotland. During that time he married a young widow, Mary Burnet, in 1669. They would have two daughters and a son.

Around 1671, Gregory discovered Taylor’s theorem. His friend Collins wrote to Gregory saying that Newton has found a similar result. Remembering his dispute with Huygens, Gregory wanted to wait until Newton published his results first to avoid another dispute. He decided to not go any further with this work out of respect for Isaac Newton.

At St. Andrews, the upper room of the library had a clear view to the south which was a great place for Gregory to put up his telescope. In 1674, he worked with colleagues in Paris to make simultaneous observations of an eclipse of the moon. With this, he was able to find out the longitude for the first time even though he had already started to work on an observatory. In 1673, the university permitted him to purchase instruments for the observatory on the condition that he would have to organize collections for funds to build it himself. He would leave St. Andrews a year later and go to Edinburgh due to the prejudice he felt against him at the university.

            In Edinburgh, Gregory would become the first person to hold the Chair of Mathematics there. However, this would be short lived because he would pass away one year later. His death was very sudden. One night when he was observing the moons of Jupiter to his students with his telescope, he suffered a stroke and became blind. He would die a few days later at only the age of 36.

Over time we can finally see just how brilliant he was. He anticipated Newton in discovering the interpolation formula and the general binomial theorem. He discovered Taylor expansions more than 40 years before Taylor discovered it himself. He had solved Kepler’s famous problem of how to divide a semi circle by a straight line through a given point of the diameter in a given ratio. He gave one of the earliest examples of a comparison test for convergence, which would essentially be Cauchy’s ratio test. And he also gave a definition of the integral which was pretty much the same definition Riemann would give later. James Gregory was indeed a great man of science.

Works Cited

"Gregory (More Correctly Gregorie), James." Complete Dictionary of Scientific Biography. Vol. 5. Detroit: Charles Scribner's Sons, 2008. 524-530. Gale Virtual Reference Library. Web. 30 Sept. 2010.

O'Connor, J. J., and E. F. Roberston. "James Gregory." MacTutor History of Mathematics. JOC/EFR, Sept. 2000. Web. 30 Sept. 2010. <http://www-history.mcs.st-and.ac.uk/Biographies/Gregory.html>.

APOD 1.6

"Io in True Color" (October 3,2010)

This astronomy picture was taken by the Galileo spacecraft, which orbited Jupiter from 1995-2003. What makes this picture interesting is that, it was taken so this is how Io would look if we were able to see it. Io is one of Jupiter's moons. Io has many volcanoes all over its surface. This is why the moon is yellow. The sulfur and molten silicate rock that are created by the erupting volcanoes have a yellowy color which is why Io is yellow. The many volcanoes on the moon are mostly cause by the friction from the tidal force between Io and Jupiter's other moons. This friction heats up the molten rock and inside of the moon which causes the volcanoes to explode. Erupting volcanoes are very common on this moon. Just looking at the picture, I believe the many black spots on the moon are where there are or were recent volcanic activity. The constant eruption and creation of sulfur and silicate rock makes the moon look very beaten up, scarred with the unappealing yellowish color. I did not know that volcanoes could be cause by the tidal gravity between other moons. This just shows how strong gravity can really be, but I can see how eruptions are so common because I can easily relate it to my experience with ceramics. If we make a sculpture, we have to hollow it out. If we don't make an escape hole to let the hot air escape when it's in the kiln, the trapped air will get hotter than the air outside and will expand causing the piece to explode. It doesn't really require a lot to cause an eruption.

APOD 1.5

The astronomy picture of the day that I chose to read about was Arp 188 and the Tadpole's Tidal Tail (9/26/10). This picture shows the Tadpole Galaxy. This galaxy does indeed look like a tadpole because of the tail of stars, dust, and gas that forms it. It is thought that the tail was formed from a close encounter with another intruder galaxy. When the intruder galaxy crossed in front of the Tadpole galaxy, their gravitational forces drew them together and the stars, dust, and gas was drawn out from the intruder galaxy as it was slung around behind the Tadpole Galaxy. Its tail of stars is about 280 thousand light years long! Eventually though, they say it will lose its tail as it gets older (just like a frog) because the stars clusters will become small satellites to the galaxy.

This is interesting because it showed how galaxies can interact with each other and what could happen from that interaction. I was not aware that galaxies could even move like that. What resulted from these two galaxies was merely a drawing out of some star clusters. In other examples that they have shown, the larger galaxy could have absorb the smaller one into itself over a period of time. I also liked the fact at how appropriately the galaxy was named because it did indeed look like a tadpole and it will become like a frog when it loses its tail.