Apod 4.4 The Bloop: A Mysterious Sound from the Deep Ocean

This picture is a visual representation of the Bloop, which was a sound recorded in the Pacific Ocean in 1997 using deep sea microphones that had been spy microphones in World War 2. In the graph, time is shown on the horizontal axis, deep pitch is shown on the vertical axis, and brightness designates loudness. It is the loudest sound ever recorded in an ocean at over 150 decibels and was audible 5,000 kilometers away and by two different microphones that were over 3000 miles apart from one another. The sound is similar to that of a blue whale, but the blue whale isn't large enough to create such a monstrous sound. Two potential explanations are that there could be a gigantic life form at the bottom of the ocean that we have yet to discover, such as a prehistoric animal that survived through the extinction periods, or that an iceberg calving, an undersea earthquake, or an undersea volcano caused the noise. Since the bloop was recorded, no other bloops have been heard.

Astronomy Cast Ep. 177: Mysteries of the Milky Way, Part 2

How many spiral arms does the Milky Way have?:
There are man different types of spiral galaxies, from normal and barred, to even smaller classifications in each broader group. The arms are caused by density waves moving through the Galaxy. When you look at the galaxy in different wavelengths, you get different data on how many arms there are. Therefore, blue light was selected as a constant of observation. In blue light, the Milky Way appears to have 2 spiral arms.
Sibling Stars: Did other stars form in our solar nebula? What happened to them?
Everything starts out bound together in a star forming region. Over time, the star-forming region stretches out and the sibling stars start to separate. The best way to match with siblings is to match the Sun's composition with other stars'. Unfortunately, non-sibling stars can match as well.
Mass-extinctions:
Seem to trend every 60 million years. Are we due?
When the solar system goes through the Galaxy's disk, it goes through areas of high and low density, we become susceptible to cosmic rays and higher asteroid rates in the high density areas.
G-dwarfs: dwarf stars in the G part of the H-R diagram. They should be more abundant than large stars, but aren't. Why?
There should be a group of stars formed right after the Big Bang that are almost purely hydrogen and helium, but we haven't found a single one yet. They are called Population 3 stars. One explanation is that without the presence of metals, only giant stars could form out of pure hydrogen and helium. The other solution is that the first stars were so giant that they lived and died before any small stars could form. This prevents any G dwarves from forming, and therefore nothing that formed before the first generation of supernovae is capable of still being alive today because the supernova polluted space with metals.
Where are the intermediate mass black holes? We've found stellar mass and supermassive black holes, but only a couple of intermediate size black holes in the whole galaxy. We don't have enough evidence currently to have any real plausible conclusions.

Astronomy Cast Ep. 176: Mysteries of the Milky Way, Part 1

There are many mysteries in our galaxy that have puzzled astronomers for many years.
Blue stragglers are stars in globular clusters that are not old and neither off of the main sequence nor are red dwarfs. These stars are high mass blue stars on the main sequence that are well above the main-sequence turn off. These stars shouldn't last more than a few millions years, but they are part of clusters that are billions of years old. One theory is that these stars formed later, but this idea does not fit our models of the universe. The other idea is that two stars collided and formed one big, bright, blue star. The two star could also be members of a binary that merged or have had mass-transfers.
Supernovae are supposed to occur every century, however our Milky Way Galaxy has not produced a supernovae since 1680. Dust clouds could have possibly blocked our sight of some of these supernovae.
Another question is whether the Magellanic Clouds are satellite galaxies or not. Due to the presence and uncertainty of dark matter, calculations are not certain about whether the galaxies are related to our own or not. Depending on calculations, the two galaxies could either be unattached and zipping past us, or could be gravitationally bound together around the Milky Way.
Proxima Centauri is believed to be part of the Alpha Centauri system, but it could also be just very close to Alpha Centauri A+B. Alpha Centauri's stars have the same composition, but Proxima Centauri has a different composition. Also, Proxima Centauri is at the farthest point in its projected orbit, so it is uncertain whether Proxima Centauri is connected to Alpha Centauri or not.
Eta Carina is a massive object in the constellation Carina. Eta Carina had a "false nova event" in 1843. Other stars that have gone through this turned into supernovas. Therefore, we could see a supernova from Eta Carina very soon.

David Levy Biography

Kenny Smith
Mr. Percival
Pd. 00
30 Apr. 2010
David Levy
David Levy is a Canadian astronomer who was born in 1948. He married Wendee Wallach-Levy on March 23rd, 1997. He has attended a multitude of universities, including McGill University, Acadia University, Queen’s University, University of Arizona, the University of Tampa, and Hebrew University, where he just in the last few months finished studying and earned a doctorate. Levy has discovered 22 comets, including Comet Shoemaker-Levy 9, which impacted Jupiter. Levy is also a prolific author and has made a big impact on recent astronomy.
David Levy’s biggest impact on astronomy has come through the study of comets. He ranks third in history in the amount of comets discovered by one person. Altogether, he has discovered twenty-two comets, including nine in his own backyard. The other comets he discovered as part of a team composed of himself, his wife, and Eugene and Carolyn Shoemaker. He even aided in the discovery of two other comets, although he is not given credit as one of the discoverers. Levy is the first person to ever discover comets using three different methods: visual, photographic, and electronic observations.
Although Levy is most famous for his numerous discoveries of comets, he has also found many asteroids. His first asteroid discovery was that of asteroid 5261 Eureka. This asteroid was not only the first asteroid Levy discovered, but was also the first Martian Trojan asteroid ever discovered. The Trojan asteroids share Mars’ orbit, so Levy can indirectly be credited with leading to the discovery of all of the Martian Trojan asteroids that we know of today. Together, with Tom Glinos and his wife Wendee, David Levy has discovered over 60 asteroids.
Levy’s most famous discovery was that of the comet Shoemaker-Levy 9. Shoemaker-Levy 9 was a periodic comet, meaning that its orbital period was 200 years or less. The comet was discovered in 1993 at the Palomar Observatory in California. The comet was the first comet to ever be discovered orbiting a planet instead of the Sun. It is believed that about twenty to thirty years prior to its discovery it had approached too close to Jupiter and had been captured by the gas giant. When the comet was discovered, it had an odd shape that could only be explained by a close encounter with Jupiter in which Jupiter’s tidal forces pulled the comet apart. As astronomers continued to study the comet, it was concluded that the comet would collide with Jupiter in July of 1994. This would be the first collision ever visually observed between two objects in our solar system or in space. Astronomers were ecstatic over the possibility of being able to see deeper into the atmosphere of Jupiter. The collisions occurred on the side of Jupiter invisible to Earth, but the collision sites were visible moments after the impact due to Jupiter’s fast rotation rate. Overall, 21 distinct impacts were observed over a six day period and the collisions formed dark, round spots that were as easy to see as the Great Red Spot and that stayed visible for months after the impacts. The discovery and subsequent impact of the comet shot Levy into instant stardom. He became a household name for several years and was bombarded with requests to do interviews for all of the major television networks.
Levy currently hosts his own radio talk show on astronomy, has written 35 books on a multitude of subjects, mostly on astronomy, is the President of the National Sharing of the Sky Foundation, and is part of the Jarnac Comet Survey in Vail, Arizona. He has received numerous awards for his many astronomical achievements, but he will be forever known for his greatest accomplishment, the discovery of Shoemaker-Levy 9.

Works Cited
"About David." Welcome. 2004. Web. 30 Apr. 2010. .
Arnett, Bill. "SL9." The Nine Planets Solar System Tour. 24 July 1997. Web. 30 Apr. 2010. .
“David H. Levy.” Encyclopædia Britannica. 2010. Encyclopædia Britannica Onlne. 29 Apr. 2010 < http://www.britannica.com/EBchecked/topic/338050/David-H-Levy>.

APOD 4.3 Ash and Lightning Above an Icelandic Volcano

The recent volcanic explosions in Iceland have created so much as that they have cancelled flights across Europe. The ash and dust has drifted across Europe and engulfed the whole continent. The ash is still thick that many planes are still left grounded. But what created so much ash? The Eyjafjallajökull volcano in southern Iceland began erupting on March 20, with a second eruption starting under the center of a small glacier on April 14. Neither eruption was particularly powerful, but the second explosion melted a glacier that fragmented lava after it cooled and the lava pieces were carried up with the rising volcanic plume.

APOD 4.2 Spitzer's Orion

The Orion Nebula, M42, is a star forming region some 4o light years across. It is 1500 light years away and is visible in the constellation Orion. The young stars in the nebula experience fluctuations in brightness and the Spitzer Space Telescope is keeping tabs on the young stars. One of the causes for the aforementioned changes in brightness is the presence of dusty, planet forming disks, which can pass between our point of view and the star's light, thus affecting the amount of light that reaches us. The brightest stars in the nebula are part of the Trapezium cluster and all of the stars in the nebula are only about 1 million years old, compared to our sun's age of 4.6 billion years. The image was taken in false color that was caused by the absence of Spitzer's liquid coolant, which ran out in 2009.

Observations

Date: 4/6/10
Time: 8:30-8:40
Location: Venice, FL
Conditions: Dark, Clear
Observations:
Venus: 10 Degrees high in the West
Brightest whole object in the whole sky.
Flickering a little.
Consistent white color
Mercury: 8 degrees high in between the West and WNW
Very faint, to the right of Venus and down a few degrees
Flickering a lot
Color changing between red and white\
**About 3 degrees of separation between the two objects.

Date: 4/7/10
Time: 8:15-8:25
Location: Venice, FL
Conditions: just passed sunset, still fairly bright near the horizon, only about 10 objects visible in total.
Observations:
Venus: 12 degrees high in the West
Very Bright
Mercury:
about 10 degrees high in the West between W and WNW
Sun still not set, so its even fainter than when observed at darker hours. Just barely visible, occasionally escaping from view for a split second because it was so dim.
*** Again about 3 degrees separation between the two objects.

APOD 4.1 Venus and Mercury in the West

All around the world, Venus and Mercury are very close together in the western sky. These two planets have just passed conjunction and are starting to slowly grow apart. The two planets will remain almost as close together as they were at conjunction for a few days, before quickly separating as Mercury plummets to the horizon. This conjunction is ideal for observations of Mercury. Mercury is often hard to identify because it is very faint. Often, the Sun's glare prevents us from seeing the closest planet to the Sun. Even when not obstructed by the Sun, Mercury is faint and hard to identify if you do not look at the sky often enough. However, with Venus' close approach, it is very easy to tell which object Mercury is. Venus is by far the brightest object in the night sky and is very easy to identify low in the west. At our latitude, the best viewing is about 30 minutes after sunset. At this point in time, both Venus and Mercury are fairly bright and easily visible.