Astro2110 – The Solar System | Aggregating the class blogs of Astro2110 at Vanderbilt

Thermus Aquaticus

Posted on April 27, 2021 by ben141414

Thermus Aquaticus is an extremophile that can survive extremely hot temperatures. It is a species of bacteria, whose scientific classification is Bacteria, Deinococcus-Thermus, Deinococci, Thermales, Thermaceae, Thermus, Thermus Aquaticus (Domain, Phylum, Class, Order, Family, Genus, Species). Thermus Aquaticus is a chemotroph, which means it obtains food through chemosynthesis. The species was first discovered in 1969 at Mushroom Spring in the Lower Geyser Basin of Yellowstone National Park by microbiologists Thomas D. Brock (Brock died on April 4, 2021, rest in peace) and Hudson Freeze.

Prior to their groundbreaking discovery, it was thought that the limit for any life was around 73^o C or 163^o F. But, contrary to that thought, this bacterium cannot live much below that temperature. Temperatures colder than 50^o C, or 122^oF, might destroy Thermus Aquaticus. A bacterium that lives at higher temperatures than most species on Earth, Thermus Aquaticus thrives at 65-70^o C, or 149-158^o F, and can survive extreme heat up to 80^o C or 176^o F.

Amazingly, bacteria like Thermus Acquaticus are responsible for the beautiful colors at Yellowstone. Many different species of bacteria create the contrasting colors because they reflect different colors. Since the discovery in Yellowstone, Thermus Aquaticus has been found in several other high-temperature environments.

Taq polymerase is a DNA polymerase that is extracted from Thermus Aquaticus. It was first discovered in 1976 that Thermus Aquaticus is very suitable for DNA sequencing due to its ability to withstand a wide range of high temperatures and protein denaturing. Taq polymerase is one of the most versatile polymerase enzymes available.

Posted in Class, Terrestrials | Tagged astro2110, blog7, extremophiles | Comments Off

Blog 6 Aristotle’s cosmology

Posted on April 23, 2021 by zvrec

In this blog, I would like to introduce Aristotle’s model of the universe. The cosmic theory from Aristotle is clearly wrong from the view of modern science. However, before modern astronomy was developed, Aristotle’s ideas about our world dominated people’s belief for thousands of years. It was embraced by scholars, philosophers, and religious leaders as a foundation for their principles.

In Aristotle’s cosmology, the universe is made up by multiple celestial spheres. Earth is located at the center of the universe. Same as his teacher Pluto, Aristotle also believes that the universe is constructed by basic elements. However, Aristotle thinks that besides the four basic elements, which are earth, fire, air and water, there exists one extra dominating element, called aether. In his view of the world, the universe contains two realms, the terrestrial realm and the celestial realm. The former one naturally covers the internal celestial sphere. The entire amount of fire, water, earth, and air makes up the terrestrial sphere. According to Aristotle, we can discover from natural observation that these four basic elements undergo transformations and interactions. Thus, this characteristic determines that all things in the terrestrial realm are material and perishable.

On the other hand, the outer celestial sphere is made up of only one element, aether. Aristotle states that aether is ungenerated, unalterable, and indestructible. The features of aether leads to Aristotle’s conclusion that all stars in the outer sphere are made up by aether. They are eternal and without a beginning, so does the universe itself. Being similar to Pluto, Aristotle’s model demonstrates his worship to circular motions. He considers stars in the heaven doing perfect circular motions around Earth. For him, circle represents perfectness and fulfillment to the natural purpose of the universe.

Aristotle’s cosmology was viewed as undoubtable truth throughout the most history of humanity. One important reason is that his cosmology was created based on his physics, and his physical theory was tightly connected to the very basis of his philosophy. In past time, people readily found Aristotle’s ideas correct, because many of his thoughts were quite intuitive if people just take into consideration of their senses and their daily observations to the nature. More crucially, there was no advanced scientific tools to prove that Aristotle was incorrect. A key loophole of Aristotle’s geocentric model was the existence of stellar parallax. Nevertheless, no competitive telescope was invented to successfully observe stellar parallax until 1838.

Posted in Class, Historical, Universe | Tagged Uncategorized | Comments Off

Comet Swift-Tuttle

Posted on April 21, 2021 by miichellewang

Comet 109P/Swift-Tuttle (which is unfortunately not named after Taylor Swift) is just one of the several thousand comets that are known to astronomers. The “P” in its name stands for “periodic comet”, which means that it has an orbital period of less than 200 years. It was separately discovered in 1862 by Lewis Swift and Horace Tuttle, hence the name. It takes around 133 years to orbit the Sun and has a diameter of 16 miles or 26 kilometers. For reference, the asteroid that wiped out the dinosaurs was estimated to have a diameter of only around 10 kilometers. Because of its massive size, some have said it has potential to wipe out humanity in a couple thousand years!

Another fascinating aspect of the Comet Swift-Tuttle is that it is actually responsible for the Perseids meteor shower, which peaks around the middle of August each year. Its name comes from the constellation Perseus, which is where the meteor shower appears to come from in the sky. Meteor showers occur when Earth passes through dusty trails left behind by comet particles and bits of asteroid pieces. When this happens, the particles disintegrate in the Earth’s atmosphere and create bright streaks across the sky. Hopefully the next time August rolls around you’ll be able to catch the Perseids meteor shower happening in the night sky.

Posted in Small SS Objects | Tagged astro2110, blog6, comet, Solar System | Comments Off

How Moons Get Their Names

Posted on April 20, 2021 by solarcecily

With advancements being made in telescopy allowing astronomers to use the astrometric, Doppler, and transit methods to unparalleled accuracy, we can’t let ourselves get behind in naming these fascinating new worlds. Before we were discovering extrasolar planets, however, we were classifying small worlds and satellites within our own Solar System. Some of the more notable bodies were given clever names hailing from Greek and Roman mythology, like the Galilean moons of Jupiter (see below) all being named after characters who interacted with the ancient deity.

Today, all moon naming is under the discretion of the International Astronomical Union’s (IAU) Working Group for Planetary System Nomenclature (WGPSN). Moons we’ve known for a while now have been given names as homages to figures in antiquity, but new satellites are given temporary names by the Central Bureau for Astronomical Telegrams (CBAT). This provisional name is a combination of the year the moon was discovered plus a number. The number corresponds to the order which that object was discovered in that year. So for example, if we discovered a new moon today, in the year 2021, but this is the 15th discovery we’ve made this year, the name would include the numbers 2021-15. Until 2013, all moons were given names, even if it was just a temporary one, but there is no longer a requirement for all of them to have names, so some satellites remain nameless.

Posted in Moons | Tagged blog6, Solar System | Comments Off

Galaxies

Posted on April 20, 2021 by 20harriganc

Galaxies are cosmic Islands of stars, gas, dust and dark matter. They span across very long distances and they are held together by gravity. There are multiple types of Galaxies as shown in the the photo above. The word galaxy is derived from the greek word “galaxias”. It means milky, which is a direct reference to the Milky way Galaxy. The Hubble deep field estimates that there are about 125 billion galaxies in the observable universe. That is a huge amount considering how vast a single galaxy is on its own. The Milky way Galaxy itself is about 100, 000 light years long itself. That comparison helps me understand how big the universe really is.

Posted in Class, Galaxies, Universe | Tagged astro2110, blog6, history, Milky Way | Comments Off

Kuiper Belt Objects

Posted on April 20, 2021 by 20harriganc

Kuiper Belt in relation to Pluto and Neptune’s Orbit.

The Kuiper Belt is a region in the solar system beyond the orbit of Neptune as shown in the photo above. Although they have only scratched the surface, there has been about 2,000 objects discovered so far in the Kuiper belt. It is said to be filled with bits of rock and ice, along with comets and dwarf planets. Among those dwarf planets includes Pluto, Eris, Makemake, and Haumea. Comets also exist with in the Kuiper Belt. It is said that comets from the Kuiper belt comets can orbit the Sun in less than 200 years. They also travel in about the same plan as the rest of the objects orbiting the sun. The belt is named after Gerard Kuiper, who speculated about objects beyond Pluto in a paper in 1951.

Posted in Class, Space Travel, Universe | Tagged astro2110, blog5, Comets, history, kuiperbelt, pluto | Comments Off

The Heart of Pluto

Posted on April 18, 2021 by solarcecily

Pluto’s beloved carotid glacier, Tombaugh Regio, has been the apple of astronomers’ eyes ever since New Horizons made its fly-by in 2015. This fly-by gave us the highest resolution images of Pluto we’ve ever been able to capture, and in these new photos, a particular feature on the dwarf planet’s surface rose to a meteoric notoriety. This region, also known as Sputnik Regio, is theorized to have formed rapidly after an impactor struck the dwarf planet’s surface, and ice filled the basin left by the crater.

Image credit: NASA; retrieved via EarthSky.org

Tombaugh Regio is an expanse of nitrogen ice, spanning 990 miles in diameter. That’s over 22% the circumference of the entire dwarf planet itself! This distance is equivalent to more than the length of Tennessee, two times over–a pretty impressive plane for a world that would only be the size of a popcorn kernel if the Earth were scaled down to the size of an nickel.

Pluto’s heart has a specific role as well on this little world, it controls the dwarf planet’s atmospheric circulation. Because of the cycle of evaporation and condensation of the nitrogen ice, winds are set in a direction opposite to the planet’s spin, a phenomenon known as retro-rotation.

Posted in Dwarf Planets | Tagged blog5, pluto, Solar System | Comments Off

Types of Kuiper Belt Objects

Posted on April 18, 2021 by miichellewang

You have likely heard of the asteroid belt located between Mars and Jupiter, but did you know we also have the Kuiper belt? It’s approximately 20 AU (astronomical units) wide and is located beyond Neptune. Several dwarf planets such as Pluto, Makemake, Haumea, and Eris are all located here. Unlike asteroids which are mostly composed of rock and metal, Kuiper belt objects (KBOs) are primarily made of frozen gases like nitrogen, ammonia, and methane. Although these objects may appear to all be the same, they can actually be categorized into three major groups: classical, resonance, and scattered.

Classical KBOs

Classical KBOs make up the majority of KBOs discovered so far. These were named “classical” because they most closely resemble what astronomers predicted objects in the Kuiper belt would look like. They are all located between 42-48 AU from the Sun and have somewhat circular orbits. Their orbits are also relatively close to the ecliptic, which is the plane that the rest of the planets orbit on.

Resonance KBOs

Resonance KBOs are named after their close association with Neptune; their orbits follow a pattern that is controlled by Neptune’s orbit. These are separated into four categories: 1:1, 2:1, 3:2, and 4:3. These numbers describe a ratio of Neptune orbits to KBO orbits. Our favorite dwarf planet Pluto is actually located in this category and is in a 3:2 resonance with Neptune. This means that for every three orbits of Neptune, Pluto orbits the Sun twice. Roughly a quarter of all KBOs follow this 3:2 resonance, and they are a subcategory known as plutinos.

Scattered KBOs

Scattered KBOs are located the furthest from the Sun and are comprised of objects that have been scattered by Neptune. They have extremely elliptical orbits and high inclinations. KBOs in this category are also the hardest to find because they are often too far away to be detected using current observational methods. Eris is the largest known member of this group.

Although located at the outer edge, the Kuiper belt contains many interesting objects that can help us learn more about the formation of our solar system.

Posted in Small SS Objects | Tagged astro2110, blog5, kuiperbelt, Solar System | Comments Off

Plutonium: Not Just a Power Source in “Back to the Future”

Posted on April 17, 2021 by connorrobbwilcox

Did you ever wonder how spaceships and shuttles have the power to take off and travel through that big black expanse we call space? Or ever thought about how these rockets survived with the limited technology we had in the 1950s, 60s and 70s during the Space Race? Well the answer has to do with the same power source from Doc Brown’s time-traveling DeLorean in the movie “Back to the Future”.

Nuclear fuel turns blue during refueling from Plutonium-238

Just like the sci-fi car, spacecrafts use plutonium for power. In the 1950s scientists and engineers developed nuclear batteries called radioisotope thermoelectric generators (RTGs) and powered them through plutonium-238 to enable spacecrafts to explore the reaches of space. Plutonium was chosen as the main power source because of its longevity and its properties of having a high heat density and emitting alpha particles. This makes it both much lighter and safer to handle than most other radioactive compounds and elements. Plutonium-238 is then converted into electrical power that operates the computers that run the craft. It also assists in the creation of power for deep space travel that would not be possible without it. Is this still efficient today? Or is there a better source of energy now? Let me know in the comments below!

Posted in Class, Space Travel | Tagged astro2110, blog6, energy, Nuclear Power, technology | Comments Off

Blog 6: Huygens’s Descent to Titan

Posted on April 17, 2021 by mattj3

The Cassini orbiter, initially launched on October 15, 1997, traveled seven years with the objective to relay observations of Saturn and its satellites. Attached to this spacecraft was also the Huygens probe, designed to enter the atmosphere and land on the surface of Titan, Saturn’s largest moon. On January 14, 2005, Huygens executed its mission; descending into Titan’s atmosphere and landing on its surface through a series of parachutes. Before the descent little was known about the surface of Titan because of atmospheric haze that shrouded the entire moon. However, images sent back to the Cassini spacecraft during Huygens’s fall and landing revealed much about Titan’s atmosphere and surface. Through the probe’s descent, much of the atmospheric composition and weather patterns could be inferred. It was observed that Titan had a much heavier atmosphere than expected due to concentrated levels of dust particles. Wind and weathering pattern could also be inferred as Huygens parachuted to the surface and was carried by winds. From this, it was concluded that winds circulated worldwide from north to south. However, the more surprising imagery came when the probe reached Titan’s surface as it revealed, through a slight haze, geography similar to earth. Present on the surface was evidence of liquid erosion, believed to have been produced through running liquid methane, that had carved out channels along Titan’s surface. Resulting in larger evidence of lakes and oceans. Also, in the final landing spot of Huygens, there were clear depictions of rounded and errored rocks that express characteristics of a previous river bed.

Video From NASA

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