Post 7

Posted on April 29, 2023 by berlinbe

The Fermi Paradox essentially states that given the size of the universe, there should be aliens. So where are they? This paradox is based on various estimation equations like the Drake and Seager equations, which are ways to estimate the number of other intelligent civilizations in the galaxy that should theoretically be able to contact us. Using different variable values as input to these equations can put the number of estimated, communicable civilizations anywhere between 1 and 10,000. However, I believe that the Fermi Paradox and any equations that attempt to estimate other civilizations hold no merit. They do not mean anything and should not be referenced as valid scientific ideas.

This is due to a few reasons. Firstly, the Fermi Paradox implies that given the size of the universe there must be other intelligent life. This assumption fails to consider that probability is relative. Just because there are 100 billion stars in the galaxy does not mean that there must be another earth-like civilization. Sure, that would put the chances of life in a given solar system at 1/100 billion, but who’s to say that 1/100 billion is a small (or large) probability in the scale of the universe?

The second issue specifically pertains to the Drake and Seager equations. In both equations, one of the variables is the fraction of planets that could support and develop life. This variable is often debated, but the fact of the matter is that we do not have even the slightest idea of its true value because our sample size is miniscule. We have a good idea for the true values of other variables in the equations like number of stars and number of planets per star, because we have a large sample size of observational evidence to back up these values. However, our sample size for number of planets that we can say, with complete certainty, either have or do not have life, is 9. We know of the planets in our solar system that only 1 has life. However, we do not know this for certainty about any other planets. Therefore, this variable holds absolutely no weight and invalidates the whole equation.

The only certainty about the presence of life beyond earth is that we do not have the slightest clue if there is life beyond earth.

Here are the Drake and Seager equations, taken from NewScientist.

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JUICE Explorer

Posted on April 29, 2023 by alicebyrnes

As discussed briefly in class, the European Space Agency (ESA) just successfully launched the Juice (formerly JUICE: JUpiter ICy moons Explorer) mission on April 14th! I had no idea this mission even existed before it was mentioned, so I decided to explore it further.

Artist’s rendition of Jupiter and its moons, sourced from The Planetary Society.

The goal of this mission is focused on Jupiter’s moons. While we have quite a bit of information about those moons just from looking at them, much of it is speculated. Ganymede’s surface features and magnetic field indicate there may be a subsurface ocean, but we have no way of knowing for sure. This is where Juice will come in.

State-of-the-art instruments on board the Juice spacecraft are designed to validate the observations from the Hubble and other telescopes of Europa, Callisto, and Ganymede’s surfaces. It’s also equipped with a radar that will be able to show internal structures of the moons up to 9 km below their surfaces. A spectrometer will be used to analyze the surface for organic molecules that could indicate life.

Unfortunately, all of this information is a little ways off. Juice won’t arrive at Jupiter until 2031, and it will begin orbiting Ganymede in 2034. But as we all know, time flies! I’m excited that we are well on our way to having more information about these moons.

Information for this blog is sourced from The Planetary Society and Science Focus.

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Binary on the Golden Records

Posted on April 29, 2023 by casciand7

The Voyager Golden Records are the successors to the pioneer plaques in that they were launched four years later and contain more information than their predecessors. As phonographic record, there are lots of sounds and images of life on Earth contained on them, which can be read in detail here. The cover of the records, which are identical, are quite interesting.

The Golden Record cover

In a previous post, I went into a bit of detail on how a unit of time and distance are established using hydrogen atoms. Skipping that explanation, the first notable engraving is the concentric circles that appear on the top left of the record. These represent the record itself, and the object on its right is the stylus used to play it. The position of the stylus shows how to start the record from the beginning. The binary around the record indicates the intended time of a single rotation (3.6 seconds) expressed in the time unit established from the hydrogen atoms.

Without getting technical, the signal on the top right shows how a picture is meant to be constructed. The 1, 2, and 3 above the signals represent the picture lines, and the binary below the number 1 represents the duration of a single picture line, about 8 milliseconds. Working downwards, the next engraving indicates that the pictures are meant to be drawn in a staggered way. Below that, there is an engraving depicting an entire picture. The number 512 (1000000000 in binary) represents the number of vertical lines per picture. The engraving of a circle is a depiction of the first photo on the record, which is used as calibration. A detailed view of the entire cover can be found here.

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Variable Stars and change in the Night Sky

Posted on April 29, 2023 by noahherrero

Image of Omicron Ceti (Mira)

Source: Digitized Sky Survey 2

Looking up at the night sky it may seem that while the stars do move around, they remain the same brightness all year round. This was a common belief pushed by philosophers like Aristotle, believing that stars are eternal and invariable. However in 1638 Johannes Howards observed the star Omicron Ceti, now known as Mira, pulsating regularly over the course of 11 months. This discovery alongside Tycho’s Supernova in Cassiopeia marked the first step towards a revolution in astronomy, breaking the notion of the immutability of the heavens.

While the history of these stars is quite vast, but today’s blog post will be focusing on how exactly stars pulsate. There are many different mechanisms that can cause a star to dim and brighten. Some are extrinsic, such as a secondary object eclipsing the primary one (Similar to planetary transits), or through rotating, putting a side with more sunspots into view. The more interesting however are the stars the pulsate due to their intrinsic properties. There’s quite of few of them however, see: RR Lyrae, T Tauri, etc, so I’ll focus on Mira types.

The attributes that define a Mira Variable are their more distinctive red color alongside very long periods of pulsation (~100 day+). The change they undergo is quite drastic going from 5 to 30,000 times their current brightness over the given period. These objects are very old red giants, which by nature undergo both hydrogen and helium fusion. For these stars are constantly expanding and contraction due to these fusion reactions not being in complete balance with gravitational interactions, which causes increases and decreases in the stars overall temperature and magnitude. One tidbit as well is that our sun is currently on track to becoming this type of star once it goes into the red giant phase. Some of these variables also undergo shifts in their period due to the re-ignition of inert hydrogen within the star causing faster oscillations. Below is a graph showing the fluctuating magnitude of the star χ Cygni:

Source: Wikipedia

There’s something I would like to preface however, and it’s that variable stars do not necessarily have to change periodically, they are simply stars that change in brightness. A non-periodic example is a cataclysmic variable star, which are the byproduct of a white dwarf and main sequence star binary system. The white dwarf’s greater density allows it to distort the other star until it begins to consume the others matter. Eventually the dwarf gets massive enough to star burning hydrogen, rapidly getting brighter, and becoming visible in the night sky. Eventually the white dwarf consumes enough mass that it turns into a type 1a Supernova, which is a particularly helpful tool when measuring distances in astronomy. In fact, Cepheids another type variable star are useful in measuring distances.

Depiction of a Cataclysmic Variable

Source: Nasa

Ultimately, Variable stars are a particularly interesting subset of stars that pulsate for a variety of reasons. For us they are helpful tools in understanding both stellar composition and measuring out to the farthest outreaches of the universe.

• Noah Herrero

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The Statistics of Life

Posted on April 29, 2023 by noahherrero

Artist interpretation of Kepler-452b, currently the most Earthlike planet discovered, which could potentially have an atmosphere and life

Source: NASA Ames/JPL-Caltech/T. Pyle

When faced with an effectively boundless universe, it inevitable to ask the question of how many other lifeforms are out there. In asking this question we tend to be a bit biased, looking for organisms just like us, harboring civilizations, and long distance communication. This developed to the Drake’s equation, which while a useful thought experiment many of the variables themselves are either vague or hard to quantify.

To solve this problem MIT astronomer Sara Seager proposed a different equation which rids of the assumption of intelligent life; instead proposing that if life were to exist on a separate world it would be detectable though shifts in atmospheric composition. The equation itself is:

N=N* * FQ * FHZ * FO * FL * FS

The first term represents how many observable stars there are, followed by fractions denoting how many of these stars are quiet (Not particularly active), contain planets within the habitable zone, with observable planets, how many of those contain life, and lastly how many have signs of detection. The big distinction in this equation is the inclusion of the term “observable”, which drastically scales down the number of planets and makes the calculations far more reasonable than the Drake’s equation. Furthermore Seager clarifies that some of the variables are already essentially known, take for example FHZ, which the Kepler satellite deduced was around 0.15 or around 1/7th of planets residing in the habitable zone.

Despite this extra precision there are still some unknown variables, and some unruly assumptions. Just like in the Drake Equation, it’s hard to find a reasonable value for FL since we simply lack a significant data size to find out the odds of life forming on a habitable planet. By extension the ability to detect life is also hard to quantify since as Seager put it, we simply do not know how many planets have significant amount of gas that signify the presence of life. Through an optimistic calculation constrained to only a specifically M class stars Seager calculated that in the following decade two planets harboring biological signatures will be observed.

Depending on a persons perspective their value could vary greatly from this value, either being dramatically larger or smaller, though that tends to be the result of pretty significant assumptions. In the end we would only truly know how much local extraterrestrial life there is out there through observing it directly, be it radio signatures or atmospheric compositions that imply biological processes. So, in the end it’s good to understand that these equations are essentially very wide shots in the dark, with no true correct answer.

• Noah Herrero

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Final Post

Posted on April 29, 2023 by dromalley
The Solar System, with properly scaled sizes

It has been a long and interesting semester, filled with learning about everything from the laws of gravity, to the instruments of astronomy, and even alien life. Over the course of this semester, my view of the Solar System has changed drastically, both in detail and much more generally. I’ve learned many surprising facts about the Solar System, from the actual sizes of the planets (which are very different from what media often shows) to some of the fascinating geological features we’ve examined on various worlds, there is no shortage of stunning things to learn about our home. Beyond these details, though, this class has changed the way I view of the Solar System’s history and evolution. Before this class, it was easy to think of the Solar System as always being the way it is, the result of the initial conditions of the Solar nebula. In reality, the creation of the system as we know it was the end of a long and complicated series of chances, any of which could have resulted in a very different system than the one we see today. This view of the solar system as a dynamic and constantly changing system is completely different than what I thought before this class, and it has made me stop taking things, even things as seemingly immutable as the planets, for granted.

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Binary in the Pioneer Plaques

Posted on April 29, 2023 by casciand7

About the size of a license plate, the Pioneer plaques were placed on the Pioneer 10 and Pioneer 11 spacecrafts with the hopes of reaching intelligent extraterrestrial life.

Illustration on the Pioneer plaque

The two circles on the upper left of the plaque represent two hydrogen atoms, the most abundant element in the universe. If you look closely, the line atop the atom flips, meant to represent the spin-flip transition of an electron, which is assumed to be universally the same. The “1” underneath the line represents both the period of this transition and the wavelength of light at that frequency. This unit of measurement is used throughout the plaque.

To the right of the woman, there are two horizontal lines depicting her height. Between them are several smaller lines. These lines represent 8 in binary (1000), where the line from before represents 1 and the “-” represents 0. The defect in the first zero is not on the actual plaque. It is also a bit ambiguous as to how the number should be read. Similarly, there are binary numbers above and below the planets on the bottom of the plaque. These figures, of course, represent the solar system (Pluto included). The binary numbers represent each planet’s distance from the Sun, where the unit is a tenth of the distance of Mercury’s orbit. Notice that the number above Mercury is 10 (1010 in binary).

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The Search for Extraterrestrial Life: Exploring Mars, Europa, and Beyond?

Posted on April 28, 2023 by theyounesadventure

Throughout history, humans have been intrigued by the possibility of life beyond our planet. With modern advancements in space exploration and technology, the quest for extraterrestrial life is more achievable than ever before. NASA and other space agencies have initiated numerous missions to explore our solar system and beyond in search of signs of life.

Mars is a promising destination to search for signs of life, and NASA’s Perseverance rover landed there in February 2021. Equipped with advanced instruments, it is capable of detecting microbial life on the planet. Additionally, the rover is collecting rock samples to be analyzed on Earth in the future.

This is the first image NASA’s Perseverance rover sent back

First image NASA’s Perseverance rover sent back after touching down on Mars on Feb. 18, 2021. 

Europa, a moon orbiting Jupiter, is a promising destination for the search for life due to its subsurface ocean that could potentially harbor microbial life. NASA’s upcoming Europa Clipper mission aims to study the moon’s icy surface and subsurface ocean to identify any signs of life. The launch date of this mission is October 2024.

Europa Clipper

Image of Europa Clipper by NASA

Astronomers have found numerous exoplanets orbiting stars outside our solar system. Some of them are in the habitable zone, the area around a star where liquid water can exist on a planet’s surface. Liquid water is essential for life, and finding habitable exoplanets is a significant milestone in the quest for alien life.

Scientists are currently studying the habitability of exoplanets in their search for potential life forms. Through analyzing a planet’s atmosphere for signs of biological activity and researching its geological features, they hope to determine if it could support life. The discovery of extraterrestrial life would be an incredible breakthrough, expanding our understanding of the universe and raising fundamental questions about the origins and nature of life. While the search for life beyond our planet continues, advancements in space exploration and technology provide renewed optimism that evidence of alien life will eventually be uncovered.

Do you believe that discovering extraterrestrial life would profoundly affect humanity’s perception of our place in the universe? Furthermore, do you think we will find proof of life beyond Earth in the near future?

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Farewell, for now

Posted on April 28, 2023 by 7smessier45
Earth’s Atmosphere, from NASA 

I have always loved the stars, nebulae, planets, and all the space in between, but I never had a chance to seriously study them until this year. I am incredibly grateful that I was able to devote two classes (and a lab!) to learning more about the processes that govern solar system formation and how we know what we know about the solar system–and space more broadly. 

After taking ASTR 1010 last fall, I appreciated being able to gain a more in-depth understanding of planetary systems and planetary formation–something that was less emphasized in the introductory class. This course has helped me better understand how our planet is and is not unique. Before this course, I might have conceptually understood that other planets had aurorae and magnetospheres, but I didn’t register them as a ‘universal constant.’ If a planet is massive enough and has a swirling, hot, conductive core, it will have a magnetosphere interacting with solar particles. I also learned about the Drake and Seager equations, the Fermi Paradox, and the amazing extremophiles that could be the key to finding life on other planets. 

If I was better at math, I would have seriously considered a degree in astronomy or astrophysics. (I’ll leave the STEM stuff to my sister.) I will continue to explore the topics on my own and help foster a love of science–especially astronomy and oceanography–in my future students and my youngest sister. And overall? I can’t wait to see where science takes us in the future, and I will be checking in on NASA/ESA accounts regularly! (And I hope some of y’all do the same!)

Until next time,

7sMessier45

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Where is Everybody?

Posted on April 28, 2023 by dromalley

The Fermi paradox is a very simple question whose answer could have massive consequences for the future of humanity: where is everybody? With equations like the Drake equation predicting a huge number of extraterrestrial civilizations, it seems odd that we have detected no signs of life outside of Earth. In this blog post, I will cover several possible solutions to the Fermi paradox, and their implications for our future.

The Great Filter

One possible solution to the Fermi paradox is the idea of a “Great Filter” which stands in the way of cosmic solutions. This filter is some “checkpoint” in the development of civilization through which most are unable to pass. This filter could be biological, environmental, or societal, and the specifics matter a great deal. If the filter were the evolution of multi-cellular life, for example, then humanity has already passed through the filter, and the reason we see no extraterrestrial life is because they have not. If, on the other hand, the great filter lies ahead of us, perhaps in the form of climate disaster or the ever-present threat of nuclear war, then humanity faces immense existential threats ahead, and the reason we see no aliens is because they have already failed the test.

A timeline of life in the universe from the ESA

Another possible solution, and probably the most simple, is that humanity happens to be one of the first intelligent species to emerge, at least in our area of the galaxy, and everybody else hasn’t caught up yet. While this is certainly a safer possibility than the great filter, and guarantees no “evil space invaders” come for us, it also means that, at least for the time being, humans are alone in the universe. While this makes for a somewhat desolate universe, it does account for the Fermi paradox without a hypothetical filter, and is certainly a better shot for humanity.

A chart depicting the game theory of the dark forest

The “dark forest” theory is perhaps the most disturbing solution to the Fermi paradox, painting a very grim picture of galactic civilization. In the dark forest theory, advanced technological civilizations are common and more or less evenly distributed. However, due to the huge distances involved, immense cultural and biological differences which hamper or even preclude communication, and inherently finite resources of the galaxy, civilizations do not reveal themselves to the galaxy. If two civilizations encounter each other under this theory, both will be faced with a choice between doing nothing, attacking, or befriending them. However, game theory reveals that for any civilization, the best choice will always be to attack. This means that the only way for a civilization to survive this “dark forest” is to hide from all others, resulting in what we see as the Fermi paradox. This is a very disturbing theory, as it not only implies immense danger to humanity, but also that countless civilizations have been violently destroyed in the history of the universe.

These are only a few of the many possible solutions to the Fermi paradox which have been put forth over the years. It should be no surprise that a question as important as “where is everybody?” has sparked intense debate among scientists and the public alike. Hopefully this blog post has opened your mind to this question, and you’ll find yourself considering it as well.

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