The subject of my blog 5 post was the TRAPPIST-1 planetary system. While learning about this system of extrasolar planets, I was fascinated by the illustrations of exoplanets that can’t be photographed by telescopes.
Tim Pyle and Robert Hurt are two artists who create renderings of exoplanets by using data about an exoplanet’s size, mass, and star temperature to create the images. Although they work off of limited data, the illustrations are about more than scientific accuracy. They help bridge the gap between the complexities of the data and the general public who may be curious about exoplanets and space exploration. There is an idea that these illustrations should be viewed as hypotheses that invite the public to engage with the possibilities of what exoplanets might look like. Some would argue against creating illustrations that could possibly be inaccurate, but I think they make learning about exoplanets more exciting and accessible to everyone.
On illustrating the TRAPPIST-1 system, Pyle said: “Having this wide range of seven planets actually let us illustrate almost the whole breadth of what would be plausible.” Illustrating TRAPPIST-1 was a collaborative effort between Hurt, Pyle, and the scientists who discovered the system. This article details some of the challenges the team encountered along the way and how they resolved them. It was fascinating to read about how a team of artists and scientists used their respective expertise to create data based illustrations!
Many scientists have theorized that we are not alone in the universe. Indeed, there are many scenarios that should lend themselves to the existence of life. The conditions inherent in theoretical models that have been developed to explain Earth’s formation and subsequent development of life exist elsewhere. Not only do they exist, but they appear in relative abundance.
Even within our own solar system, there exist several Jovian moons that harbor conditions that could be conducive to extremophile life. The methane rivers of Titan and the potential subsurface oceans of three of Jupiter’s moons: Europa, Ganymede, and Callisto, harbor conditions that could very well allow life to thrive.
A model of Europa’s interior, including the existence of a potential subsurface ocean. Courtesy of NASA/JPL.
Outside of our solar system, scientists have detected 200 “terrestrial” exoplanets (explain what this means) and 1,691“Super Earth” exoplanets. Extrapolated observations from the Kepler space telescope indicated that there may be as many as 40 billion Earth-sized planets in a companion star’s habitable zone.
But we have yet to find any life outside of Earth. We have searched vigorously; but we have found absolutely nothing. Why? 1938 Physics Nobel laureate Enrico Fermi supposedly posed such a question in 1950 in casual conversation with some of his physicist friends. Ever since, the apparent contradiction between the absolute lack of observed advanced extraterrestrial life and the ample conditions for its existence have borne Fermi’s name as the Fermi paradox.
If the only life that exists elsewhere is archetypically similar to that on Earth (meaning that it is also composed of DNA, responds to environmental stimuli, reproduces, and so on) then other worlds resemble Earth in crucial aspects (such as mass, density, atmospheric composition, etc.) should be those that harbor life. If we are looking at only Earth-like worlds, we can frame the Fermi paradox as a competition between two theories: the mediocrity principle and the Rare Earth hypothesis.
The mediocrity principle suggests that life on Earth is not particularly special and that the chemical elements that make up life, and even the complex combination of features that make Earth habitable, are highly unlikely to have occurred only once, especially in our vast cosmic plane. Adherents to this theory include physicist Stephen Hawking, who said that “the human race is just a chemical scum on a moderate size planet, orbiting round a very average star in the outer suburb of one among a billion galaxies.”
Opposing this theory is the Rare Earth hypothesis, which argues that Earth’s situation is the result of an incredible number of improbable coincidences that are prerequisites for the formation of life. Both the mediocrity principle and Rare Earth hypothesis serve as “answers” to the Fermi paradox, but whether or not you believe them is based upon your understanding of human understanding and your belief in the expansion of our knowledge’s horizons.
Both approaches have their respective flaws. The mediocrity principle confidently asserts the existence of completely unverified life elsewhere on a self-admittedly incomplete body of evidence. On the other hand, the Rare Earth hypothesis restricts its predictive capacity by limiting itself only to the highly specific conditions which formed itself, possibly discounting a large number of otherwise habitable planets which could potentially harbor extraterrestrial life.
But ultimately, there exists only one solution to the Fermi paradox. We either find extraterrestrial life, or we die trying.
Astrobiologists at NASA use data from many NASA missions to study the possibility of life on other worlds. Here are a few ways they use data from other missions to support the NASA Astrobiology Program:
The Chandra X-ray Observatory is a telescope that detects emission from extremely hot regions of space (exploded stars, galaxy clusters, etc.). Astrobiologists use data from Chandra to study the conditions of planetary system formation. This gives insight into the distribution of radiation and how that may contribute to the habitability of planets.
The HPF provides researchers with high-precision measurements of infrared signals from stars close to us. The HPF’s precision may help detect habitable planets near cool stars. This can help advance the astrobiology program’s goal of finding planets with climates/conditions that can sustain liquid water on their surfaces.
NASA partnered with the European Space Agency (ESA) for the JUICE mission, collecting data on Jupiter and observing Ganymede, Callisto, and Europa. This will help astrobiologists study how habitable planets may form near jovian ones. Ganymede, Callisto, and Europa have become targets for astrobiologists to study because of the possibility that liquid water under their icy surfaces could be habitable for life.
Extremophiles are organisms, usually microbacteria, that can survive in extreme environments. These environments are characterized by conditions uninhabitable to humans. The Grand Prismatic Spring in Yellowstone National Park, is iconic for its bright, seemingly unnatural colors. However, these colors are a result of extremophiles, specifically, thermophiles! Thermophiles are classified as “heat-loving” organisms, and are one of many common types of extremophiles. There are also acidophiles (acid-loving), anaerobes (oxygen-hating), halophiles (salt-loving), and many more!
Extremophiles are frequently used as proof for the probability of life on other planets. If there are organisms that can thrive in conditions unimaginable to humans, there must be life on other worlds that we would never expect. For instance, probability of acidophiles living on Io, one of Jupiter’s moons, due to it’s high volcanic activity and sulfuric acids.
Extremophiles are fascinating creatures, and give us hope for life in the universe beyond our own!
One of the more morbid questions that astronomers have debated over the last few decades has been the possibility of the end of the universe. With the widespread acceptance of a model of the universe that is in some way finite, there are questions about how the state of that universe could change over time. There are largely two options given the state of astrophysics, depending on the relative sizes of the forces of dark energy and gravity.
The first that was originally popularized was the “Big Crunch”, a sort of reverse big bang. This was rather romantic, as it provided a nice sort of symmetry, and also inspired thoughts of the crunch resulting in a new big bang, thus creating the possibility of an infinitely recreated universe. In this model, the forces of gravity eventually overwhelm the expansion of the universe, causing it to shrink in on itself, accelerating inward until all mass ends up in a singular point, the crunch.
The second is the “big rip”, or the “big freeze”. In this model, the forces causing the expansion of the universe are never reversed by gravity, and the finite amount of energy in the universe causes all matter eventually to be torn away from itself. This was called the “big freeze” because it means that all matter will eventually be isolated, unable to interact with all other matter, meaning the universe would eventually enter a static state, with each particle eternally separated from every other.
Galileo (February 15, 1564 – January 8, 1642) made major strides in the argument for heliocentrism, observing sunspots and the phases of Venus, two pieces of information that seemed to point to the imperfection of the celestial world and that the Sun was the gravitational center of the Solar System about which all the planets orbited.
With his observations of sunspots, he was able to argue that the Sun was changing and therefore could not be made of ether (Aristotelian idea), meaning that the Solar System was imperfect. This poked a major hole in the argument of the Catholic Church who believed in geocentrism because Christian principles were steeped in the ideas of Aristotle and Plato who held the view that the celestial world was perfect.
Observing the phases of Venus was also impactful in his argument for heliocentrism because the phases only made sense with a heliocentric model of the universe. Venus can go through phases from our perspective because it is between the Earth and the Sun.
Galileo had major cultural and religious impact on the world, arguing that true theologians should work to marry Science and Scripture, and that if the Church did not embrace new Science, people would start to use it as an argument for atheism or belief in a different god once Science caught up and disproved geocentric views. While Ptolemy’s model saved face for the Church during his life, Galileo argued in his infamous letter to the Grand Duchess Christina that it would be disproven, and the Church should respond to this with open arms instead of suppression, as suppression would cause Science and the Church to become even more split.
Two Major Events
1. First permanent North American European settlement
Jamestown, Virginia was settled by the English in 1607 during Galileo’s lifetime.
2. Don Quixote, one of the most famous works of literature of all time, was published.
This work was published in the early part of the 1600’s, and it remains one of the most popular works of literature in European history.
Shakespeare is widely regarded as the most accomplished playwright of all time, and he lived during Galileo’s lifetime. He is responsible for works such as Hamlet, Macbeth, and Romeo and Juliet.
Descartes was one of the most famous philosophers of the Scientific Revolution. He wrote one of the most concrete justifications for first principles (not-so-fun fact: Al-Ghazali did it first, and though there is not sufficient evidence to say that Descartes had access to his work, their arguments are similar but Al-Ghazali was marginalized by a Eurocentric mindset in Science and Philosophy), proving self-existence by the presence of first-person perspective.
Reflection
I enjoyed this homework assignment because I was able to combine my notes from several different classes, not even having to look things up because I had studied these people/events in greater detail in other classes. I have been keenly interested in Galileo since I took professor Weintraub’s class on the trial of Galileo, so it was fun to talk about him and see what other famous people/events occurred at the same time. It is interesting to think about the fact that René Descartes would have had a much smaller impact on the world if Galileo had not done what he did, as it kickstarted the Scientific Revolution and shifted the center of Science from the Church to its own practice.
In this blog post, I will give an overview of my experience in astronomy so far, and what I am excited about in the future.
I have found ways to integrate astronomy in many conversations. My favorite example is when I related the world of astronomy to a concept that came up during an investment banking interview. The interviewer was shocked about how in depth I went into the threshold regarding the creation of jovian vs. terrestrial planets.
In the future, I want to dive deep into the telescope industry. In some of my earlier blog posts, I discussed companies that are creating highly powered telescopes, larger and stronger than anything we have seen before.
I also want to read more about new black holes that are discovered and what their implications are on our existing understanding of the universe. I recently read about Gaia BH3, a black hole that was recently discovered.
The Fermi Paradox questions the discrepancy between the vastness of the universe and the apparent lack of intelligent life. This paradox has been discussed at length with many experts and as all paradoxes go, there is no clear conclusion. However, there does appear to be strong rebuttals to the paradox.
One rebuttal that I find to be convincing is that the intelligence that we have defined as humanity is most likely significantly different from the intelligence of “aliens”. Our mission to colonize space is viewed as a manifestation of humanity’s intelligence but there is nothing to suggest that colonization is an inherent motivation amongst “intelligent” beings. It may be the case that the intelligence that an alien civilization has does not compel them to explore or colonize space.
Another strong explanation for the Fermi Paradox is the doomsday proposition which posits that civilizations will most often meet their “doom” and become extinct before being able to colonize space. This is compelling because even on Earth, we have only been able to meaningfully explore space through probes and spacecrafts in the past couple decades. Earth is a geologically active and decently friendly planet but despite its friendliness, we’ve had multiple extinction level events. The timeframe for humanity is incredibly short in the context of the age of the universe so it may be the case that the lack of evidence for intelligent life makes complete sense when we consider how short of a time we have been looking.
I had a great time learning about and using the Drake Equation during our class period. However, after doing more research, I found many people who are heavily against the Drake Equation. In this blog post, I will review some of their main arguments.
First, on “Y Combinator Hacker News”, I read: “I really dislike the drake equation because it’s the epitome of bad science — when someone enters value for the variables they have no idea what is reasonable, absolutely no idea — is it 0.1 or 0.0000000000000000000000000000001 we have no way of knowing.”
After reading this comment, I did understand where they were coming from. It was something I struggled with when doing the Drake Equation myself. It was hard knowing what to estimate, especially when the numbers are so small.
However, some people defended the Drake argument on this site. They stated that the Drake equation is more “creative” and gives people perspective on how insignificant they are in relation to the entire universe. It also tells people that there is a significant chance that we are not alone in this universe that we live in.
Knowing about all the planets in our own solar system made us wonder if there are other planetary systems out there as well. And there are!! But how did we detect these extrasolar planets?
There are four ways to detect extrasolar planets. The simplest way, but not always the easiest way, is direct observation. That’s exactly what it sounds like: using telescopes to look for planets and observe the spectra of those planets. Only a few planets have been detected using direct observation, since these faraway planets may not be able to be seen by using the telescopes we have now.
We can also use the astrometric method, which involves observing a star and seeing whether it changes position over time. Recall that a planet and its star are both involved in the orbit around their center of mass (even though it doesn’t look like that because the star is usually much more massive than the planet so the center of mass is actually inside of the planet!). From this, we can conclude that if a star wobbles, there must be a force acting on it, which is the force from a PLANET orbiting! This method is only really useful for discovering large planets that are far from their star.
Another method is to use spectra and see if there is Doppler shifts in the star’s spectra. We can use that to figure out if there are planets orbiting the star. This method is great for finding large planets with smaller orbits.
Our final, and my favorite method, is the transit method. This method can only be used if a planet is edge-on when viewed from Earth, and is awesome for finding small planets!! We observe whether the star gets dimmer in regular time intervals (this can show that a planet is moving in front of the planet, thus blocking out some light) and then conclude the existence of that planet with follow-up observations using other methods. The star’s brightness can be graphed, and seeing recurring curves shows that it’s the same planet moving in front of the star.
Today, over 5,000 exoplanets have been discovered, and so many potential exoplanets are still being observed! Learning about other planetary systems is really cool, because we can see similarities between our solar system and other ones, as well as learn about new properties.
