Friday, January 28, 2011

APOD 3.2

Hidden Treasures of M78 (27 January 2011)

This apod shows a picture of M78. It is about 1,600 light-years away and is located in the the constellation Orion. This is a large, bright, and well known reflection nebula. The blue seen in this nebula is caused by the reflection of wavelengths which is why it is a reflection nebula. When interstellar dust grains are near a bright star, clouds of these dust particles scatter short wavelengths of visible starlight more readily than long wavelengths. This produces the blue color that is seen in the nebula. There are many more examples of reflecting nebulae like the Iris Nebula (NGC 7023) and the Witch Head (IC2118). 
This picture was taken by Igor Chekalin who won the Hidden Treasures 2010 astrophotography competition held by the European Southern Observatory. Seeing this photograph and the other photos that were entered, it's amazing what these amateur astronomers could do.
Also in this picture, in the bottom right, is McNeil's Nebula. It has a yellowish color and was apparently discovered by an amateur astronomer, Jay McNeil who was testing out his new telescope by focusing on the area around M78. The story behind the discovery of McNeil's Nebula was interesting to read because I would assume that other professional astronomers with access to observatories and high tech equipment would have already discovered it long ago.

Friday, January 21, 2011

APOD 3.1

Alnitak, Alnilam, Mintaka (January 21, 2011)

This picture shows the stars that makes up Orion's belt. In the lower left is Alnitak, in the middle is Alnilam, and in the upper right is Mintaka. They are all second magnitude and blue supergiant stars that are hotter and more massive than the Sun, but much younger than our sun. Together they are known as Orion's belt. Alnitak means the girdle. Alnilam means "a belt of pearls". And Mintaka comes from the Arabic word for belt. They are about 1,500 light-years away and came from Orion's interstellar clouds. In the lower left of the image the Horsehead Nebula and Flame Nebula can be seen. It seems that eventually the fate of Alnitak and Alnilam is to become a red supergiant like Betelgeuse and explode as supernovae. Mintaka will also be famed in death due to the other star's explosions.
I picked this apod because we have just discussed these three stars yesterday in starlab. We did not go into much details, besides their names, and this was a good way to learn more about these stars that I have often seen. It was interesting to know just how massive and bright they were. Alnitak alone is 10,000 times more luminous than the sun and a planet like Earth would have to be 300 times farther from Alnitak than Earth is from the Sun for life like ours to survive.

Friday, January 14, 2011

Observations (1/13/2011)

Yesterday morning on January 13 at around 6:10 am, I was able to see Venus from my driveway in Osprey. It was visible in the southeast and it was very bright. It was the brightest thing in the morning sky because there was no moon. The skies were very clear and other constellations and stars were visible. I was able to see ursa major in the north. I was not able to completely see scorpius, but I was able to see the star Antares a little below Venus. It was a small red glimmering light.

APOD 2.10

"A Sun Halo Beyond Stockholm" (January 10, 2011)

This picture was taken last year overlooking Stockholm, Sweden. It shows the sun surrounded by a halo and two sundogs each one to the right or left of the sun. The halo and sundogs surrounding the sun are caused by the ice crystals created in the atmosphere. When ice crystals form in the atmosphere in hexagonal prisms, they can create these atmospheric events. Halos come from the way small ice crystals in the atmosphere scatter sunlight into different angles. The quality of a halo depends on the type and quality of the ice crystals that produce it. When these crystals flutter to the ground, they are mostly parallel to the ground with their faces flat. When this happens, each crystal can act like a lens, refracting the sunlight to form sundogs, also know as parhelia. The first halo seen around the sun is the 22 degree halo. The fainter second halo seen in the picture is the 46 degree halo which is rarer. These halos can also occur around the moon.

This was an interesting APOD because most of the time for me, I focus more on the events and objects that occur at night like the stars and moon. I have never really focused on the sun before, which is what we are currently learning about. Even though we have mentioned sundogs before in class, I was never sure what they looked like so it was pretty exciting to see this picture. It was also great to know that these events could occur with the moon. I have previously seen a moon halo before but I wasn't quite sure about the cause.

Wednesday, January 12, 2011

Sun

Tuesday, January 11, 2011

Quarter 2 Astronomer: Heinrich Olbers


            Heinrich Wilhelm Matthias Olbers was a German astronomer. He was born on October 11, 1758 in Arbergen, near Bremen, Germany. He was the eighth child out of the sixteen children of Johann Jürgen Olbers. His father was a Protestant minister. He became interested in astronomy when he was around fourteen, but the institution he attended in Bremen at the time barely taught any mathematics or science. So, to better understand astronomy, he taught himself mathematics and tried to compute the solar eclipse of 1774.
            In 1777, he started to study medicine in Göttingen under the guidance of Blumenbach and Ernst Baldinger. He also started to attend lectures in physics and mathematics by G. C. Lichtenberg and A. G. Kästner. Kästner was in charge of the small observatory at Göttingen. Even though he learned from all these people, he still mainly studied astronomy on his own. His biggest interests were with comets. His interest started in January 1779. He used his observations of Bode’s comet to calculate its orbit. In 1780, he independently discovered a comet that was also being observed by Montaigne at the same time.
            Even with his great fascination for astronomy, he was still mainly a physician. In 1781, after he received his medical degree, he went on a study trip to Vienna. He visited hospitals during the day, and spent his nights in the Vienna observatory. At the end of that year, he settled down in Bremen and started an extensive medical practice. Mainly through his efforts, inoculation was introduced in Bremen and he was praised for his work during several cholera epidemics.
            In 1785, he married Dorothea Köhne. She would die a year later after their daughter was born. In 1789, he was remarried to Anna Adelheid Lurssen. They would have a son. After his daughter’s death in 1818 and Lurssen’s death in 1820, he finally retired from active medical practice to devote the rest of his life to astronomy. He had an observatory put in on the second floor of his house using its two large windows for his telescopes. His library became one of the best private astronomical collections in Europe. For over fifty years he carefully collected astronomical literature and cometography that was almost complete.
            At first he was too busy with medicine to do astronomy when he first moved to Bremen. But in 1786, he met J. H. Schröter. Schröter had a private observatory in nearby Lilienthal which was one of the best equipped on the continent and they worked closely together for many years. In 1796, Olbers discovered a comet and calculated its parabolic orbit with a new method that was easier than the one used by Laplace. He wrote a letter to F. X. von Zach, the director of the newly found observatory on the Seeberg, near Gotha. He asked him whether his argument on this new method should be printed and asked advice for how it should be done. After von Zach read the argument and used it to receive excellent results to find the orbit of the comet of 1779, which gave many astronomers difficulty, von Zach took it upon himself to see that Olber’s argument was printed. It appeared at Weimar in 1797 titled, Über die leichteste und bequemste Methode, die Balm eines Kometen am einigen Beo-bachtungen zu berechnen. His new method would make instantly establish him among the leading astronomers of his time. His new method was used throughout the nineteenth century.
            When the first asteroid was discovered by G. Piazzi on Jan. 1, 1801, he noticed a star like object that moved during the following days. He sent out this information to other astronomers. Even though it was soon realized to be a new planet that Piazzi would name Ceres, it disappeared before more observations could be made. At that time it was still impossible to compute an orbit from such a small arc without assuming the eccentricity. However, Gauss was able to calculate it by a new method, and it was Olbers who found the new planet a year later where Gauss had calculated it to be. This was the start of their lifelong friendship.
            After Ceres, Olbers discovered a second asteroid, Pallas, on March 28, 1802. With the discovery of a third asteroid, Juno, by Harding at Lilienthal in 1804, Olbers was able to use their orbits where they approached each other to discover Vesta on March 29, 1807.
            One last thing that he was greatly known for is Olber’s paradox. According to the paradox, if we accept an infinite, uniform universe, the whole sky would be covered by stars shining as brightly as our sun. He explained the paradox of the dark night sky by assuming that space isn’t absolutely transparent and that some of the interspace matter absorbs a very small percentage of starlight. This effect is sufficient enough to dim the light of the stars so they look like points in the dark sky.
Olbers was respected and admired by many of his contemporaries. He worked with many of them including Gauss, Bessel, Encke, and Schröter. He also encouraged many young astronomers and helped them gain positions at various observatories. He died on March 2, 1840, but being the humble man that he was, he would claim that his greatest contribution to astronomy was leading Bessel to become a professional astronomer.
Works Cited
"Heinrich Wilhelm Matthias Olbers." 1911 Encyclopedia Britannica. 27 Oct. 2006. Web. 05 Jan. 2011. <http://www.1911encyclopedia.org/Heinrich_Wilhelm_Matthias_Olbers>.
"Olbers, Heinrich Wilhelm Matthias." Complete Dictionary of Scientific Biography. Vol. 10. Detroit: Charles Scribner's Sons, 2008. 197-199. Gale Virtual Reference Library. Web. 5 Jan. 2011.

Saturday, January 8, 2011

Observation (12/20-21/2010)

I observed the lunar eclipse from my driveway in Osprey between the night of the 20th and the morning of the 21st. The skies were clear and I was able to see the full moon. I would often go out every half hour starting at 1 am to see the shadow fall on the moon. As the shadow got bigger and bigger and covered more of the moon, it started to turn a orange/reddish color. Around 3 am, we were able to see the total lunar eclipse in the west.