Thursday, May 24, 2012
Astronomy Cast Episode 234- Tunguska Event
On June 30th of 1908, as strange explosion occurred over the northern part of Siberia, north of Lake Baikal. Astronomers are unsure as to what exactly this event was or what it was caused by, however, it had a huge impact on Siberia and the area surrounding it. In fact, the explosion was heard in places so far away as Britain.
It wasn't until the 1920's that scientists began researching what had actually happened. On a trip to Siberia, scientists noticed much tree destruction in various intriguing patterns. At first, scientists thought that this was the cause of a meteor colliding with the Earth. However, on further inspection, they decided that a meteor was not large enough to create such widespread destruction. They were also unable to find a crater, which would have been formed, thus supporting that this was probably not the result of a meteor.
Instead, they began to believe that it could have been a comet that began to either melt, ionize, or just blow up as a result of entering Earth's atmosphere. They further determined that it must have been a comet sever meters in diameter, thus causing a big enough explosion to destroy what it did, but leave no crater. After testing some other theories, scientists verified that this theory is the most probable of all of them.
Zooniverse!
On zooniverse I have been able to identify 537 craters on the moon and classified 709 stars and galaxies. I hope this was enough for the blog post, I'm not completely aware of its requirements.
Tuesday, May 22, 2012
Observations Q4
At approximately 830 on 5/22/12 I was able to observe the Moon and Venus side by side. With binoculars I was even able to see the crescent shape of Venus. I was also able to see several spring constellations such as Ursa Major, Ursa Minor, Draco, Leo, Virgo, Canis Minor, Canis Major, Arcturus, and Sextans. I started observing around 8:30pm and stopped at 1130pm.
Monday, May 21, 2012
Jan Oort Biography
Jan Oort was a Dutch astronomer who made major contributions to our knowledge of the structure and rotation of the Milky Way Galaxy. Oort studied comets as well and provided evidence for his theory, now widely accepted, that the Sun is surrounded by a distant cloud of ice-rock objects that has become known as the Oort Cloud. Oort studied stellar dynamics under Jacobus Kapteyn at Groningen and worked at the University of Leiden from 1924 to 1992. In 1927 he confirmed Bertil Lindblad's hypothesis of galactic rotation by analyzing motions of distant stars through red and blue shifts. At this time Oort was also able to calculate that the Earth is 5900 parsecs from the center of the Galaxy. During World War II Oort started his compatriot Hendrik van de Hulst on the successful search for the 21-cm spectral line of neutral hydrogen and after the war led the Dutch group that used the 21-cm line to map the layout of the Galaxy, including the large-scale spiral structure, the galactic center, and gas-cloud motions. In 1950, based on his analysis of the well-measured orbits of 19 long-period comets, Oort proposed the existence of a vast repository of frozen cometary nuclei. The Oort cloud covers vast segments of space, starting somewhere between 2000 and 5000 AU from the sun with an outer boundary somewhere around 100,000 and 200,000 AU. He later showed that light from the Crab Nebula is polarized, confirming Iosif Shklovskii's suggestion that the emission is largely due to synchrotron radiation.
Sunday, May 20, 2012
Astronomy Cast Episode 225-Ice in Space
Many thing in our solar system are made of ice, for example, comets, rings, moons, and some dwarf planets. Recently, astronomers have asked the question, "where does all this ice come from?"
To begin, astronomy cast traveled to NASA to discuss plans involving the New Horizons mission, which plans to send spacecraft to the dwarf planet of Pluto, and beyond. This mission plans to capture images of many items in our solar system that are composed primarily of ice. They learned that there is a freeze line that exists somewhere in between Jupiter and Saturn, and once that line is crosses, ice becomes extremely evident in many celestial objects, such as the rings of Saturn. In the outer solar system, however, you enter a region where most objects are composed completely of ice, as opposed to partially made of ice.
We believe that many of these objects are formed where they currently exist, which explains and supports the existence of the freeze line. Parts of the Oort Cloud and Kuiper Belt are believed to have formed elsewhere, and were pulled into orbit by larger, stronger gravitational forces. Scientists have studied where and how the objects have formed. They have concluded that ice can form, not just from water, but from any molecule capable of vaporizing when exposed to extremely high temperatures. In the early solar system formed, the sun emitted many atoms and other such items, which eventually became solids once they reached the outer area of the solar system, where it was cold and the warmth of the sun had little effect.
Friday, May 18, 2012
APOD 4.8
A mere 2.5 million light-years away, the Andromeda Galaxy really is just next door as large galaxies go. So close, and spanning some 260,000 light-years, it took 11 different image fields from the Galaxy Evolution Explorer (GALEX) satellite's telescope to produce this gorgeous portrait of the spiral galaxy in ultraviolet light. While its spiral arms stand out in visible light images of Andromeda (also known as M31), the arms look more like rings in the GALEX ultraviolet view, dominated by hot, young, massive stars. As sites of intense star formation, the rings have been interpreted as evidence Andromeda collided with its smaller neighboring elliptical galaxy M32 more than 200 million years ago. The large Andromeda galaxy and our own Milky Way are the dominant members of the local galaxy group.
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