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Blog #8 Drake Equation
Photo summarizing the Drake Equation and possible variables.
The Drake Equation is our best estimate for the number of communicating extraterrestrial civilizations that exist in outer space with whom we might be able to communicate. The equation was originally devised in 1961 by the astrophysicist Frank Drake and focuses on a series of assumptions about the frequency of habitable planets and the likelihood of life developing on those planets. The equation has been used before as a way to understand the thinking behind the likelihood of extraterrestrial life in the Milky Way and the Universe. Unfortunately, the numbers behind each variable in the Drake Equation is a subject of debate with a defensible estimate for each leading to very different estimates for the number of communicating alien civilizations. For example, estimates of the number of habitable planets per solar system range from 0.1-5 planets per star. Similarly, the fraction of life that is intelligent is difficult to estimate, as we have only one example of a planet where life has developed and only have one where intelligent life has developed as a frame of reference. Despite the disparities between estimates for each variable, there has been much more discourse covering the possibility of intelligent alien life and more advances in the field of astrobiology since the introduction of the Drake Equation. The equation has highlighted the importance of searching for habitable planets and understanding the conditions that are necessary for life to develop. It has also led to the development of projects such as the SETI (Search for Extraterrestrial Intelligence) Institute, which uses radio telescopes to search for signals from other civilizations. The ongoing search for extraterrestrial life will improve the accuracy of our Drake Equation estimates.
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Blog #7 Extremophiles
Photo of an extremophile water bear captured using an electron microscope.
Extremophiles are creatures which are capable of living in extreme environments beyond what one might imagine are the limits of life. Extremophiles have attracted attention from the scientific community because of their potential to exist in the most extreme environments in outer space. One specific type of extremophiles, halophiles, are able to survive in highly saline environments with the ability to thrive in places such as the Dead Sea. These organisms are able to balance the salt levels in their cells in order to survive extremely salty conditions. Another type of extremophile, the thermophile, is capable of living in the extremely hot temperatures upwards of even 60 degrees Celsius. Extremophiles could be the most important organisms we have here on Earth for the field of astrobiology because they demonstrate how life might exist in extreme environments on other planets. Adaptations shown by extremophiles could potentially be used by scientists here on Earth for biotechnological improvements in salt-tolerance and heat-resistance. More extremophiles are likely to be discovered in the coming years leading to even more developments in the field of astrobiology.
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Blog #6: Detecting Extrasolar Planets
The photo above features the transit method of detecting extrasolar planets.
Detecting extrasolar planets is a very delicate and challenging task for scientists. The distances between stars and relative sizes of stars compared to planets make it extremely hard to pick them out. Stars are also typically a billion times brighter than planets. There are a number of different methods that have been tried to detect extrasolar planets. Direct imaging is one method used to capture images of the planet using a telescope as it orbits its host star. This method is largely unsuccessful because the light from the planet is often overwhelmed by the much brighter light from the star. This is mainly useful for larger planets. Often times, scientist are forced to infer a planet’s existence by observing gravitational anomalies. Almost all of what we know about extrasolar planets comes as a result of indirect methods either by detecting gravitational or brightness effects on the host star. The next method, the astrometric method, requires measuring the motion of a star caused by the gravitational pull of an orbiting planet. This is useful but often hard to measure because of the very slight effects of a planet’s gravity on the star. Another method is the Doppler Method which involves measuring a red or blue doppler shift on light emitted by a star after being affected by the pull of gravity from a planet. Lastly, the Transit Method also requires a great deal of precision by carefully monitoring the brightness of a star system over an extended period to detect a potential eclipse or transit of a planet. Like other methods, this one has its weaknesses including not being able to detect planets located far away from their host star as there isn’t enough time to see a detectable pattern in the dips in brightness with each orbital period or if the planet is especially small. Scientists typically will try to use multiple methods in order to confirm the existence of an extrasolar planet. We do not know for certain the properties of these extrasolar planets or even if they fall into the terrestrial and jovian categories we have in our solar system. As the powerful James Webb telescope begins operations, we should be able to answer more questions about other planets in the future.
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Blog #5: Pluto
The above photo was captured by the New Horizons Spacecraft and enhanced by NASA in 2015.
Pluto is classified as a dwarf planet and is located in the Kuiper Belt in the far reaches of the Solar System. The average surface temperature on Pluto is around -233°C. This is because Pluto receives very little sunlight due to its distance from the Sun. Pluto orbits the sun about once every 248 years and remarkably also has five moons surrounding it on its highly elliptical orbit around the Sun. The largest of the moons, Charon, was discovered in 1978 and is considered a turning point because it allowed astronomers to calculate the mass of Pluto for the first time. Pluto had been known to exist since its discovery in 1930 by astronomer Clyde Tombaugh, but it was hard to study until extremely powerful telescopes were developed to capture its small size. The hypothetical view of outer space from Pluto would be incredible with the moon Charon taking up much of the sky and the unobstructed view of light from the rest of the universe. Charon and Pluto are tidally locked and have a binary orbital pattern around a center of mass slightly outside of Pluto. Much of what the scientific community knows about Pluto was discovered during the New Horizons mission which launched in 2006 and finally arrived at Pluto in 2015. We now know that Pluto once had active geologic activity and its surface contains mountains as big as the Rockies in the United States, bewildering scientists. Pluto is not known to have any source of internal heat powering this activity. We still have much to learn about Pluto and its origins which could make it an appealing target for an orbital mission in the future. Considering the success of the New Horizons flyby, the orbital mission could provide groundbreaking new information to learn more about all planetary activity even beyond our solar system.
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Blog #4: Nuclear Fusion
Nuclear fusion is the process that drives star light formation and prevents the force of gravity of the star from collapsing into itself. In a nuclear fusion reaction, two smaller nuclei, typically hydrogen isotopes, bond together to form a helium atom while immense amounts of energy are released. The fusion between smaller atoms continues to release energy until the iron atom is formed in which case the fusion bonds now require more energy than is released by the reaction. This is why many stars begin to die once it’s core transitions to iron. The difference in mass between the old and new matter created is equivalent to the that times the speed of light squared or e=mc^2. These reactions as far as we know require an immense amount of heat to occur such as at the heart of a star and enables massive amounts of energy to be released. Although scientists would love to have cold fusion available on Earth for easy energy production, unfortunately there is no known way to cause nuclear fusion without immense amounts of heat and energy to start.
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Blog #3 Formation of the Solar System
The formation of the Solar System is truly a testament to our good fortune of life being possible on a planet located in the “Goldilocks Zone” near the Sun. The initial conditions allowed for not only Earth to be composed of rocky elements such as carbon but for the Earth to be protected from flying space debris by larger Jovian planets composed of mainly hydrogen and helium located a further distance from the Sun. For countless reasons Earth is lucky, and the orbits we observe today indicate the early Solar System happened to have a composition of rocks and metals located closer to the Sun where temperatures were well-suited for them to condense. Lighter elements like hydrogen and helium tended to be absorbed into the larger clumps of matter located a large distance from the Sun because the temperatures allowed for more accretion.
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Celestial Navigation Techniques Blog #2
Before any GPS or easy to use maps, explorers were completely reliant on the stars and their hunches to determine their location during their travels. In the Northern Hemisphere, it was much easier to determine latitude because of the conveniently located star Polaris just above the northern celestial pole. Using the Sun is also a possibility for navigation, but more precise measurements of dates and the path of the ecliptic are required for an accurate determination. Navigators have used tools like the sextant featured above since at least the 1700s in order to measure precisely their position in the oceans. The Ancient Greeks created similar items like the astrolabe which was very important and useful with hundreds of different astronomical uses varying from navigation to timekeeping. In modern times, global positioning systems have satellites orbiting the Earth act as “artificial stars” which are able to accurately send radio signals to travelers below.
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Historical Astronomers in Context
- Nicholas Copernicus was important to science for creating a model of the universe that placed the sun at the center. The sun-centered model was different from the Earth-centric model that had long been more popular and supported by the church.
- He was also a famous mathematician and astronomer. In the lifetime of Copernicus, Christopher Columbus discovered the Americas in 1492 after sailing across the Atlantic Ocean. Another event that happened was the painting of the Mona Lisa by Leonardo Da Vinci along with other famous works of art.
- Leonardo Da Vinci was a famous Italian painter and inventor who lived just before Nicholas Copernicus. His contributions to engineering include rudimentary ideas of tanks, flying machines, and parachutes among others. He also contributed to the depiction of the human form and three-dimensional figures in the field of art.
- This assignment made me realize what a revolutionary time the late 1400s must have been in Europe especially considering that in the span of just a few years people became aware of the existence of the Americas and the heliocentric nature of our solar system. Previously, almost everyone who lived on Earth was unaware of either of these important facts that are common knowledge in modern times. I know that the 1400s were considered the beginning of the Renaissance Era in Europe with major contributions in science, philosophy, and art. Sometimes it’s hard to imagine that geniuses like Leonardo Da Vinci lived most of their lives under the common belief that the Earth was the center of the universe and monumental discoveries such as the Americas were still yet to be made. Copernicus and his heliocentric model of the universe contributed significantly to European modernity along with these other famous figures mentioned.
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Blog #1: The Power of Ten
The Power of Ten video puts into perspective the miniscule size of not only individuals on Earth but of the Solar System entirely. At only 3 minutes into the video, we were already far beyond the Solar System with so much time remaining. Not only was I struck by the immense scale of the universe, but I was even more fascinated by the level of detail and intricacy at even the smallest units of measurement we know. The same building blocks apply to everything for billions of light years across the whole of the universe. The distance between galaxies also was startling to me as its hard to imagine the size of the empty chasms of space that separate us from other galaxies. The increasing rate of expansion detected in the universe also indicates that one day it might be impossible to even see some of the galaxies visible today. The other scary thought is the fragility of Earth at the mercy of such a large universe. The complexity at the atomic level and the specific forces required for us to live comfortably are truly a miracle.
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