Learning about the planets in our last few classes (RIP senior year) reaffirmed for me that the earth is indeed very small compared to the other planets in the solar system. But then I read that 99.8% of the mass in the solar system is still contained within the sun! Even though the gas giants are so massive, they’re still so small compared to the sun, and then the sun is an average size star with some stars up to 100 times bigger.
After every class, I feel deeply humbled by how small we are in the grand scale of things. But sometimes I read statistics like this that provide a new angle to appreciate just how much larger other objects are in the universe.
The aurora borealis and aurora australis – often called the northern lights and southern lights – are mysterious and unpredictable displays of light in the night sky. The most common occurrences of this phenomena take place at higher northern and southern latitudes, less frequent at mid-latitudes, and are almost never seen near the equator.
Auroras demonstrate the connection between the Sun and the Earth. The energy that comes off of the Sun is carried toward Earth by solar winds. As these particles approach Earth, they interact with Earth’s magnetic field. This field deflects a majority of these particles, but while doing so a huge cavity in the magnetosphere is created. When the amount of energy in the magnetosphere becomes too large, it loses its equilibrium. In order to become stable again, the excess energy is released into the acceleration of electrons. Essentially, the electrons transfer their energy to the oxygen and nitrogen atoms and molecules, ‘exciting’ them. As the gases return to their ground energy state, they emit photons, small bursts of energy in the form of visible light, creating the aurora.
Auroras which are usually green can occasionally show red, blue, violet, pink, and white in long, narrow arcs. The different colors of the aurora that are displayed depends on which gas is being excited by the electrons, and to what degree it becomes excited. High energy electrons cause oxygen to emit green light, while low energy electrons emit red light. Nitrogen normally gives off a blue light. The blending of all these colors can lead to the purples, pinks, and whites that we detect. Not much is known on how the shape of the aurora is determined, but scientists hypothesize that it may have something to do with where the electrons originate from, and what causes their gain in energy.
With the COVID-19 outbreak, a virus that has infected over 90,000 people worldwide, I’ve started to wonder how this may impact our wellbeing on an environmental level. Global warming, a phenomena caused by human activity, such as the releasing of carbon dioxide and other greenhouse gases into the atmosphere poses many consequences for Earth’s inhabitants. With people in quarantine and air travel down, coronavirus has the potential to drop CO2 emissions by only 1-10%. Journalists propose that this virus could pose benefits for the climate.
While others propose a warming world could be encouraging the emergence and spread of new infectious diseases like COVID-19. Rising global temperatures will shorten winter seasons which will benefit potential disease-carrying agents and enable them to spread further North. Thoughts?
The aurora borealis, or aurora australis if in Southern Hemisphere, is one of nature’s most dazzling phenomena consisting of massive bands of colorful light streaking across the sky. This spectacular light show, despite its captivating beauty, actually portrays the deadly solar radiation spewing out from the sun and largely dissipating when coming into contact with Earth’s magnetic field.
Due to the high temperature of the Sun, millions of degrees Celsius, collisions between gas molecules are not only frequent, but explosive. With the Sun’s rotation and holes in its magnetic field, these free protons and elections are hurled from the Sun’s atmosphere and carried by solar wind towards Earth. These highly radiative particles are largely deflected by Earth’s magnetic field, as shown in image #3 – the magnetosphere, the “bubble” that surrounds Earth and acts like a shield against solar radiation.
However, as these immense waves of radiation and charged particles hit the outer layers of the magnetosphere, the lower layers are exposed, and magnetic field lines direct the remaining trapped stream of particles towards the poles. As a result, when this charged mass enters Earth’s upper atmosphere, these particles collide with oxygen and nitrogen, producing the rippling curtains of light across the night sky. The colors of aurorae are indicative of the type of collision occurring in the atmosphere, as well as the altitude in which they occur. Particles colliding with oxygen usually produce green-yellowish and red light, while colliding with nitrogen produces violet (collisions with molecular nitrogen), and occasionally blue colors (collisions from atomic nitrogen). Blue light signifies nitrogen up to 100 kilometers in altitude above Earth while violet, of nitrogen above 100 kilometers. Green light is oxygen up to 240 kilometers and red, oxygen above 240 kilometers.
This highlights the significance of Earth’s magnetic field and atmosphere, as Mars used to have a magnetic field as well before disappearing billions of years ago. This disappearance resulted in solar winds stripping its atmosphere and any water on the surface, leaving Mars a dead and empty wasteland as we know of it today.
As we have learned so much about the solar system, much of our knowledge comes from telescopic observations, ground-based and those in Earth’s orbit, as well as spacecraft explorations. Robotic spacecraft operate primarily with preprogrammed instructions and carry radios that allow them to communicate with controllers on Earth. Having sent robotic spacecraft missions to numerous moons, asteroids, comets, and each of the planets within our solar system, we have been able to learn the general characteristics of all of these bodies.
Robotic missions into space fall into four categories: flybys, orbiters, landers or probes, and sample return missions. Flybys go past a world just once and continues on its way, with fuel only necessary during launching and when the spacecraft must change from one orbit to another. Once on its way, the spacecraft can maintain its orbital trajectory through the whole solar system without using any fuel at all due to the lack of friction in space. As a result, flybys are generally cheaper than other missions. Occasionally, the trajectory of flybys may allow additional fuel savings by permitting use of the gravity of each planet to help boost it onward to the next planet, a gravitational slingshot. Orbiters, on the other hand, orbits the world it is visiting, allowing for longer-term study. However, they are usually more expensive than flyby missions as launch costs depend largely on weight, and orbiters must carry additional fuel for changes from interplanetary trajectories to a path that puts it into orbit around another world. The most up-close study of the bodies in our solar system comes from spacecraft that send landers to the surfaces or probes into the atmospheres of other worlds. This allows for the data collection of pressure, composition, local weather monitoring, and close-up surface views of the other planets, moons, asteroids, and comets. Finally, we have sample return missions, in which spacecrafts make round trips to return samples of the world it has studied back to Earth. So far, sample return missions have only been to the Moon and to asteroids, along with a highly anticipated sample return mission to Mars within the next decade or so.
With continuously progressive technological advancements, the coming years promise many new discoveries as scientists work endlessly toward more ambitious goals and launching more and increasingly diverse missions.
In conversations surrounding the transition from fossil fuels to green energy, solar, wind, and biofuels are the most common alternatives that are brought up. Solar energy, as the name implies, comes from the sun, but wind energy and biofuels made from energy crops are ultimately also derived from converted solar power. But what if we could skip the middle-man and create a small star right here on Earth – and harness the power from nuclear fusion? Stars obviously have an advantage in their enormous mass and gravity that can produce the high temperatures and densities required to overcome the electrostatic force between two positively-charged nuclei, so recreating these conditions on Earth is extremely difficult and dangerous.
Drawing of the ITER tokamak and integrated plant systems, as found here
In Europe, the ITER reactor, a $20 billion, multi-national effort, is 60% of the way toward its 2045 target for generating energy. The ITER reactor utilizes a tokamak (a Russian acronym that stands for toroidal chamber with magnetic coils), which uses electrical currents to ionize hydrogen molecules to form a plasma. By using strong magnetic systems, the hot plasma is confined in the shape of a torus, and the heat generated from the fusion reaction will eventually be captured in the form of steam and drive turbine generators to produce electricity, just as in traditional coal-fired plants.
A concept that has always intrigued me is the possibility of life on Earth. It seems like every topic we cover reveals another statistical improbability that has allowed life to exist on Earth at all. For example, we are just far enough from the sun that we have an atmosphere, but not so far from the sun that our planet is completely frozen. Our atmosphere blocks out harmful rays from the sun, but traps just enough heat to keep the entire Earth warm the whole day. The earth is big enough to support a sizable human population but not so large that humans are crushed by the force of gravity. The list goes on.
This conversation also opens a can of worms for many people regarding religion and the possibility of the creator of the universe (which I obviously don’t want to get into here).
Brief Graphic Depiction of Probability of Life on Earth. NASA Exoplanet Exploration.
Posted inClass, Universe|Taggedblog4, life|Comments Off on Blog #4: Statistics Behind Our Solar System
Spacecraft is a topic that takes relatively simple mechanics and merges it with the already fairly complex topic of astrophysics to create an extremely complicated topic that has gained notoriety for becoming considered one of the most difficult professions in existence (think of “this isn’t rocket science”). Something interesting to me about spacecraft is this: the money, time, and effort that goes into designing and engineering a spacecraft, but this could all be lost if a launch goes wrong or if communication is lost with the craft.
A particular spacecraft that amazes me with its complexity, size, and versatility is the Space Shuttle Orbiter. According to this CNN post, the US government was predicted to have spent at least $174 billion on the shuttle alone by the time the shuttle went into its official retirement (2010).
We all remember learning the mnemonic device in elementary school: My Very Excellent Mother Just Served Us Noodles (or whatever variation you prefer). Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, the eight planets of our solar system. But what do these names actually mean? How do planets and moons and other stuff in our solar system even get their names? And what about the various mountains and crevices on the actual planets, do those features get names?
Of course, all languages have their own names for the planets and their moons, but when discussing the official scientific names we must turn to the IAU. The job of the International Astronomical Union is ” to promote and safeguard the science of astronomy in all its aspects,” including the official names of all things in space. In their terms, “unambiguous astronomical nomenclature.”
There are a few steps on deciding on these official names, and it all starts with the discovery of the moon or feature. Once the thing-to-be-named is properly confirmed to exist, several names are considered by a Task Group. Names successfully reviewed by the Task Group move onto the Working Group for Planetary System Nomenclature (WGPSN). If the WGPSN gives the final approval for the name, it is immediately entered in the Gazetteer of Planetary Nomenclature, the official reference for all solar system names.
Let’s take a short flip through of the Gazetteer and dive into some planetary naming.
Mercury – named after the Roman god of commerce, travel, and thieves because it moves so fast across the sky. Mercury has no moons. Themes for naming planetary features include abandoned cities, words for “snake” and “hot” in different languages, and significant works of architecture.
Venus – named after the Roman goddess of love and beauty, because it is the brightest and most beautiful planet. Venus also has no moons. Themes for naming planetary features include different types of goddesses, mythological heroines, and women who have made outstanding contributions to their field.
The Moon – in other languages it is known as Luna, Lune, Mond, and Selene. The Moon is Earth’s satellite. Themes for naming features on the Moon include significant cosmonauts, astronomers, and scientists, as well Latin terms for weather and other abstract concepts. Although the Moon has the most well-developed nomenclature since it is the easiest to study, only twenty eight craters on the Moon are named for women out of the 1586 craters. For more information on this disparity and these remarkable women, I would recommend reading The Women of the Moon by Daniel R. Altschuler and Fernando J. Ballesteros.
Mars – named for the Roman god of war, appropriate for the striking red planet. Mars has two moons, Phobos and Deimos (fear and panic respectively). These are the names of the mythological horses which pulled Mars’ chariot. Themes for naming planetary features include names from classical mythology, names of rivers, and small towns and villages of the world. Features on Phobos are named after scientists who studied these two moons and people/places from Gulliver’s Travels by Jonathan Swift. Features on Deimos are named after authors who wrote about the Martian satellites.
Jupiter – named after the Roman King of the gods, the god of sky and thunder, which is an appropriate name for the largest planet in our solar system. Jupiter has 79 moons, which are all named after the mythological children of Jupiter. Themes of the features on the satellites include:
Io – heroes and gods related to fire, sun, and volcanoes, mythical blacksmiths, and people/places from Dante’s Inferno
Europa – gods, heroes, and places from Celtic myths, as well as Celtic stone rows
Ganymede – gods and heroes of the ancient Fertile Crescent civilization, places from Egyptian myths, and astronomers who discovered Jovian moons
Callisto – all names are drawn from myths and stories of cultures of the Far North, such as Norse, Inuit, Sami, etc.
Saturn – named for the Roman god of wealth and agriculture. In Greek mythology, Saturn’s equivalent is the father of Jupiter’s Greek equivalent. Saturn has 82 moons, which are named after Greek giants, titans, and titan descendants. Themes of the features on some of the satellites include:
Mimas – people/places from Le Morte d’Arthur legends
Enceladus – people/places from Burton’s Arabian Nights
Tethys – people/places from Homer’s Odyssey
Dione – people/places from Virgil’s Aeneid
Titan – islands on Earth that are not politically independent, people/places from Middle-earth (from the novels of J.R.R. Tolkein), characters from the Foundation series by Isaac Asimov, and names of planets from the Dune series by Frank Herbert
Uranus – named after the Greek deity of the heavens, who is the father of the Greek equivalent of Saturn. Sir William Herschel, who first discovered Uranus, originally wanted to name it “Georgium Sidus” or the Georgian planet in honor of King George the III. Uranus has 27 moons, which are named for magical spirits from Shakespeare or Alexander Pope. The reasoning could be that Uranus, as the god of the air, would be attended by spirits of that realm such as fairies and sylphs. Themes of the features on some of the satellites include:
Neptune – named after the Roman god of the seas, a perfect match for Neptune’s bright blue color. Neptune has 14 moons, named after minor water gods in Greek mythology. Themes of the features on these satellites follow the same trend.
Dwarf Planets
Pluto – named after the Roman god of the underworld. Pluto has 5 moons, which are also named in relation to the underworld. Features on Pluto also follow this naming theme. Themes of the features on some of the satellites include:
Charon – destinations of mythical space and fictional vessels/voyagers of space and other exploration
Kerberos – dogs from literature, history, and mythology
Hydra – legendary serpents and dragons
Ceres – named after the Roman goddess of corn and agriculture. Ceres has no moons, and its features are named after gods and goddesses of agriculture and agricultural festivals.
An artist’s depiction of the SOHO spacecraft via NASA
For my post this week, I decided to explore and learn about a spacecraft that I was not familiar with. After some research, I came across SOHO. SOHO is the longest-lived Sun-watching satellite to date. SOHO over its lifetime has been able to observe two full 11-year solar cycles and discover thousands of comets close to the Sun.
SOHO is the result of a joint effort between NASA and the European Space Agency (ESA). The satellite was launched on December 2nd, 1995 from Cape Canaveral, Florida and contains 12 different scientific instruments. In December of 2020, SOHO will have reached 25 years of continuous exploration and observation of the Sun.
SOHO has fundamentally changed ideas about what the Sun is over the course of its lifetime. According to Bernard Fleck, the ESA project scientist for SOHO, the satellite has changed our conceptions of the Sun from “a picture of a static, unchanging object in the sky to the dynamic beast it is.” Without SOHO, our knowledge of the Sun would not be where it is today.
