The Search for Extraterrestrial Life

The Drake Equation

One of the most exhilarating topics in astronomy to me is the search for extraterrestrial life. The Drake Equation is one way to estimate the number of active and communicative extraterrestrial civilizations in the Milky Way. This equation was formulated in 1961 by Frank Drake to stimulate intellectual discussion about the factors that influence extraterrestrial life development. The equation contains several variables such as the rate of stars suitable for development of intelligent life, the number of stars that have planetary systems, and the number of planets per star system that could have an environment suitable for life, among others. 

Additionally, the Seager Equation, proposed by Dr. Sara Seager, is a parallel version of the Drake equation to estimate the number of habitable planets in the universe. THe equation contains variables such as planets with biosignature gasses and factors in the star’s type and planetary atmosphere to predict whether a planet is hospitable for life. Therefore the Drake equation could be used to estimate the number of civilizations on other planets that are similar to our human civilization, whereas the Seager Equation could approximate the number of extraterrestrial life such as microbes or extremophiles!

NASA’s missions, like the Kepler Space Telescope and the James Webb Space Telescope are designed to find planets in the habitable zone of their stars and use the principles laid out by these two equations to prioritize what star systems they observe. Looking forward, the continued advancement in exoplanet research and astrobiology will bring us closer than ever to answering the question if we are alone in the universe. I am very hopeful that we will be able to find extraterrestrial life in my lifetime, but for now this search will undoubtedly inspire my continued interest in the cosmos.

Project Orion

Artist Rendering of Project Orion

Due to the vast distance between stellar systems, a spacecraft traveling beyond our Solar System and into a different star system must reach speeds close to the speed of the light. Project Orion was a theoretical design from the late 1950s and early 1960s that proposed using nuclear explosions for propulsion. The basic idea was to detonate a series of atomic bombs behind a spacecraft that had a massive, shock-absorbing “pusher plate” to absorb the blasts and propel the spacecraft forward.

Project Orion began in 1958 by Ted Tayllor and Freeman Dyson under the company General Atomics. A main engineering challenge of this project was the design of the pusher plate which was required to withstand many nuclear explosions. From initial calculations, an Orion spacecraft could reach speeds up to 9-11% of the speed of light. Although this is faster than any human-made object has ever reached, it pales in comparison to matter-antimatter annihilation rockets which could be capable of obtaining a velocity between 50% to 80% of the speed of light. 

At the speeds Orion would travel at, it would require a flight time of at least 44 years to reach Alpha Centauri, the closest star to our Sun. Although this is still a long time, it is a significant improvement compared to our current capabilities. Also, this project could provide a great practical use for the world’s large stockpiles of nuclear weapons.

Solar Eclipse in Nashville

A picture I took of the eclipse in Nashville at 1:53 PM CST on April 8, 2024.

Around 2 pm today on Apr 8, 2024, I was fortunate enough to see the eclipse reach its peak in Nashville amidst intermittent cloud cover. Although Nashville wasn’t in the path of totality like it was in 2017, it was very close!

For a quick background on solar eclipses, a solar eclipse happens when the Moon passes directly between the Sun and the Earth, and when the Moon completely blocks the sun, it is called a total solar eclipse. A partial eclipse, when the Moon only blocks a part of the Sun, occurred here in Nashville today! Additionally, an annular eclipse is a special type of partial eclipse when the Moon blocks the Sun but leaves a small ring around the edge. 

If you are lucky enough to be in the path of a total solar eclipse, they can last from 10 seconds up to almost 8 minutes. The longest solar eclipse projected will occur on July 16, 2186 and last 7 minutes and 29 seconds! Unfortunately, we probably won’t be around to see that; however, come 2044, the next solar eclipse will be visible from the United States again. 

You may have also heard in the news that NASA is launching sounding rockets and high-altitude planes to conduct research during the eclipse period today. Observing the sun during eclipses can help scientists better understand how solar material flows from the sun and about our ionosphere which can help scientists validate and improve models to predict potential disturbances to our communication systems.

Overall, seeing the eclipse was a fascinating experience and really offered a unique perspective on astronomical events. I hope you all had the chance to see it today too!

Europa

Jupiter’s Moon Europa

Alien life could very well be found in our own Solar System, and Europe is a prime candidate! Being one of Jupiter’s moons, Europe is one of the coolest moons of the giant planets in our solar system. It is about 90% the size of our Moon, with an equatorial diameter of 1,940 miles. However, if we replaced Europa with our Moon, it would be much, much brighter as its surface is made of water ice so it reflects 5.5 times the sunlight that our Moon does. 

The surface of Europe is also one of the smoothest in our entire Solar System and has streaks and cracks on its ice which are caused by the large tidal forces from Jupiter. These tidal forces are also what is expected to be responsible for the geothermal heating that allows for Europa’s subsurface ocean to be in a liquid state.

Out of all of the moons and planets in our solar system, Europa has one of the strongest potentials for life due to the subsurface ocean that exists below the moon’s icy shell which also helps protect from radiation. The Hubble Space telescope also observed water vapor plumes coming from Europe, further solidifying this theory.

Future missions to this moon include NASA’s upcoming Europa Clipper and ESA’s JUICE mission. Specifically, the Europa Clipper is a spacecraft specifically designed to observe Europa thoroughly. This spacecraft will make almost 50 flybys of Europa at closest approach altitudes as low as 16 miles above the surface to scan nearly the entire moon. Its magnetometer will study Europa’s magnetic field, with a goal of confirming that Europa’s subsurface liquid ocean exists, as well as measure its depth and salinity. Hopefully, from this mission, we will gain an even better understanding of this fascinating Moon which could one day lead to the finding of alien life!

Planet Nine

Planet Nine

A great point of debate among astronomers in the present day is the possible existence of Planet Nine. This celestial body is theorized to exist beyond Neptune, but has not been directly observed. In the past few years, Caltech researchers have found evidence of Planet Nine, and hypothesize that it has a mass about 10 times that of Earth and orbits about 20 times farther from the Sun on average than Neptune. This means it would take between 10,000 to 20,000 years for Planet Nine to make a full orbit around the Sun. However, there is some compelling evidence that has led to astronomers believing its existence.

The evidence that gave Planet Nine a potential to exist emerged from peculiarities in the orbits of trans-Neptunian objects (TNOs). These are distant celestial bodies that are located beyond the orbit of Neptune. Some TNOs have been observed to exhibit unexpected orbital patterns that suggest gravitational influence from a celestial body. Caltech researchers in 2016 showed that custard orbits of several TNOs could be explained by the presence of a massive planet on an elongated orbit around the Sun.

Despite these findings, the absence of direct observation has made many astronomers very skeptical about the possibility of Planet Nine truly existing. Many scientists propose that the orbital anomalies result solely from the collective gravitational effects of many small objects in the Kuiper Belt. 

Regardless if the planet exists or not, the search for Planet Nine is advancing the understanding of our own solar system and gives us more knowledge about the distribution of mass in the outer solar system.  Do you all think Planet Nine exists?

Geology of Mars

Olympus Mons

Mars has a fascinating geology that is very comparable to Earth in many ways and also shows its very dynamic history. A well known geological feature on Mars is Olympus Mons, the largest volcano in the solar system, which stands at a height of approximately 16 miles and spans 374 miles in diameter. To compare, the largest volcano on Earth is Mauna Loa which is 6.3 mi high and the volume of Olympus Mons is almost 100 times larger than that of Mauna Loa. Because Mars lacks plate tectonics, its crust remains stationary and the lava continues to pile up in one place into one very large volcano. 

Another very cool feature of Mars’ geology is Valles Marineris, a massive canyon system. This system runs along the Martian equator and is 2500 mi long and reaches depths of up to 4 mi. This dwarfs the Grand Canyon in Arizona which is only 500 miles long and about 1 mile deep. To put this in perspective, Valles Marineris is as long as the United States and spans about ⅕ the entire distance around Mars. Valles Marineris formed from the cracking of the Martin crust as the Tharsis region uplifted and the planet cooled. It was widened by erosional forces, and potentially formed by water channels that have been found on the eastern flanks of the rift.

Mars’ surface also shows signs of ancient rivers and lakes which is evidenced by dried-up river valleys, and lake beds. This means that Mars once had a climate that could support liquid water and potentially life. As you can see, Mars’ geology is super fascinating and really helps to unravel the history of the planet. One thing’s for sure, future astronauts will have some pretty spectacular places to check out on Mars!

Retrograde Motion

Retrograde Motion

Retrograde motion is a fascinating celestial phenomenon that has puzzled astronomers and stargazers for thousands of years. Imagine you were stargazing across multiple nights and traced the planets as they danced across the sky, but suddenly, one of the planets stops, reverses direction, and then after a while, resumes its original motion with the stars. This phenomenon is called retrograde motion.

When the Greeks first developed their geocentric models of the solar system, retrograde motion posed a big problem. If the Earth was truly at the center of the universe, the planets would always move eastward with the stars. However, the fact that the planets stopped, reversed course to move westward, then stopped and resumed their eastward motion had the Greeks questioning the accuracy of their models. To this point, the Greeks proposed a complex system where all the planets other than Earth follow circular orbits within circular orbits. This became known as the Ptolemaic system, formulated by the astronomer and mathematician Ptolemly around 150 CE. Although we know now that the Ptolemaic model was not correct in its explanation of planetary motion, Ptolemy’s tables derived from his model were so effective at predicting positions in the night sky that they were used for over 1,500 years!

It wasn’t until the 16th century that Copernicus proposed a heliocentric model to try and account for the slight errors that resulted from using Ptolemaic’s model. Copernicus’ model was much simpler and stated that every planet orbited the sun in a perfect circle. Although this model accurately described the retrograde motion as an optical illusion, it still had inaccuracies as Copernicus did not realize that planetary orbits are actually eccentric. 

Overall, retrograde motion was once a baffling phenomenon to astronomers that had a pivotal effect in reshaping the general consensus that the Earth is not truly at the center of the universe and instead orbits the Sun as all the other planets do in our Solar System!

Historical Astronomers in Context

Isaac Newton (January 4, 1643 – March 31, 1727): Isaac Newton was a pivotal figure in astronomy and physics due to his concepts of the laws of motion and universal gravitation. Newton’s laws of universal gravitation, which were formed from his three laws of motion, state that every particle attracts every other particle with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers. Newton’s work, known as the “Philosophiae Naturalis Principia Mathematica ” is known as one of the most important works in science and combines the concepts of planetary motion and gravitational theory. Newton also built the first practical reflecting telescope, which today is known as the Newtonian telescope and is still a very popular design.

Painting of Isaac Newton

Events during Newton’s lifetime:

1. The English Civil War (August 22, 1642 – September 3, 1651): The English Civil War took place between supporters of Charles I and opposing groups of Charles’s kingdoms in the British Isles over Englannd’s governance and issues of religious freedoms. The war ended with the execution of Charles I, leading to the coronation of Oliver Cromwell.
2. The Great Plague of London (1665 – 1666): The Great Plague of London was the last major outbreak of the bubonic plague to occur in England and killed an estimated 100,0000 people, almost a quarter of London’s population. 

People alive during Newton’s lifetime:

1. Johann Sebastian Bach (March 31, 1685 – July 28, 1750): Bach was a German composer and musician and is known today as one of the greatest composers in music history. He is known for his orchestral music from cello suites and sonatas, to keyboard and organ works. 

Reflecton

It was very interesting to explore the historical context and events that unfolded during the lives of these famous astronomers. It gave me a totally new perspective and glimpse into this transformative period where so much scientific discovery was taking place. It’s also interesting that thanks to Einstein’s work, we now know that some of Newton’s views of gravity were a bit underdeveloped and didn’t reflect the true dynamics going on for every scenario, like Mecurry’s peculiar orbit around the Sun. 

Blog 1 – Light Speed

The speed of light is a fascinating topic that has significance from everyday life to the vast expanse of the cosmos. The speed of light is the speed at which light travels through a medium, and for a vacuum, this speed has been defined as 299,792,458 m/s. This speed is almost incomprehensible to us due to its magnitude. For example, if you moved at the speed of light, you would circumnavigate the equator approximately 7.5 times in one second.

Because of this finite speed, everything we observe is a glimpse into the past. This is particularly applicable to astronomy due to the vast distance of objects observed. Astronomers are able to use this principle and look further back in time by studying more distant objects. Our nearest neighbor, the Andromeda Galaxy, is 2 million light years away, meaning we see what it looked like 2 million years ago. This allows astronomers to garner a better understanding of the universe’s history.

Along with visible light, all forms of electromagnetic radiation travel at the speed of light. Therefore, this speed governs both the light viewed from distant stars on Earth, as well as communications with distant space probes. NASA’s Voyager 1 probe, the most distant satellite in interstellar space which was launched in 1977, takes nearly a day (22.5) hours for a transmission to reach the spacecraft. This delay is due to the spacecraft being more than 15 billion miles away from Earth, and the speed of light, or electromagnetic radiation in this case, sets the ultimate limit of the speed of these communications. This is even applicable to the communication delay during the Apollo missions, where it took 1.255 seconds for communications to reach the moon from Earth, as seen in the graphic below.

Speed of light from Earth’s surface to Moon’s surface

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Hi! I’m Jack, a senior studying Mechanical Engineering at Vanderbilt University. The image below shows where I’m from: Jupiter, Florida! Sadly, my hometown was not named after the planet, Jupiter.

Image of Jupiter, Florida

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