It's being called the Great American Eclipse, because on Aug. 21, for the first time in U.S. history, a total solar eclipse will be seen only in this country - and it's the first total solar eclipse since 1918 to move from coast to coast. You can learn everything you need to know about the eclipse here, and in this post you can learn about the people who are most eager to study the phenomenon - astronomers.
Astronomy is one of those subjects many people find interesting but don't really understand. What do astronomers actually do? And how do they do it? How did they even become astronomers? What follows is a Q&A that explores those and related issues with Amber Porter, a lecturer in astronomy and space science at Clemson University, where the 2017 eclipse will be seen in totality for 2 minutes and 37 seconds on Aug. 21.
Q: Let's start with your story: When did you decide you wanted to be an astronomer and why? And what was your educational route to becoming one?
A: I have been interested in astronomy for a long time, but I don't think I knew that I wanted to be an astronomer until I decided to apply to graduate school. My love of science first became apparent in middle school and blossomed throughout high school. Learning facts in my science classes was never enough and I always wanted to know "why" nature acted the way it does. I enjoyed my chemistry and math classes in high school, but nothing compared to my earth space science class, so that is what really sent me down the path of pursuing physics and astronomy. After graduating from high school, I received a bachelor of science in physics at Lycoming College in 2009. I wasn't sure what to do next and the decline of the economy meant that there were very few jobs for college graduates at that time in their fields of study. When I received a job offer to work with some of the smallest aspects of nature by colliding subatomic particles together, I realized that I was much more interested in studying the biggest objects nature can offer - stars and galaxies. So the next step was receiving a Ph.D in physics from Clemson University in 2016, where I studied the three-dimensional shape of exploding stars in distant galaxies.
Q: The three-dimensional shape of exploding stars in distant galaxies? Sounds fascinating. Before I ask you why that is important to know, let's talk broadly about astronomy. How many different kinds of astronomers are there, and what do they do?
A: This is an interesting question because scientists love to place objects into groups as a classification method and there are numerous ways that we can subdivide astronomers. An astronomer may identify themselves based on the part of the universe that they study. For example, there are planetary astronomers who want to determine what planets and their atmospheres in our solar system are made of and how they have changed over time. There are also astronomers who prefer to study what stars are made of and the life stages of these giant balls of gas. People who study cosmic rays, supernova explosions or black holes may call themselves galactic or extragalactic astronomers. Astronomers also describe themselves according to what part of the electromagnetic spectrum they tend to use to study an object such as radio astronomer or gamma-ray astronomer. These are people who collect the longest and shortest wavelengths of light, respectively, that are emitted by their object.
The last classification I'll offer is this: You often hear astronomers divide themselves into observational, computational, and theoretical regimes. Observational astronomers are those that use telescopes to collect the light of celestial objects for further analysis. Astronomers often require complex computer codes to build models of the universe in our computers. We can then tweak the parameters of the model like turning a knob to try to fine-tune our models to match the reality of the information we collected from space.
Q: So in what subjects do all astronomers have to excel? Math? At what level? Which sciences? What other subjects should wannabe astronomers study in school?
A: In high school, wannabe astronomers should study as much math as possible up through calculus. Once in college, a physics or astronomy major will also take a variety of other higher level mathematics courses such as statistics, differential equations or linear algebra.
Taking a breadth of science courses as well is very helpful for astronomers. All of science is connected. We use the laws of gravity from physics to understand planetary orbits, we study how fusing nuclei in the bellies of stars produces a variety of elements on the periodic table, and we try to decipher what planets and their atmospheres are made of to see if they contain the building blocks for life that we study in biology classes.
Gathering data from telescopes is a small piece of being an astronomer. Much of our time is spent on computers analyzing data and writing papers so computer programming and English classes are essential as well. As you can see, astronomers excel at nearly all subjects taught in schools. I think it is important to note that I myself never felt particularly gifted at math so if you are currently struggling in any one subject, don't feel as though you can never become a scientist or astronomer. I think it is much more important that you have the tenacity to work on hard problems and the desire to ask "why."
Q: What exactly do astronomers see when they look through telescopes?
A: Contrary to popular belief, astronomers often do not look directly through telescopes anymore. If you are stargazing for pleasure on a clear night, you will still look through the eyepiece of a telescope. However, the large telescopes that professional astronomers use typically have primary mirrors with diameters between 1-10 meters (or approximately 3-33 feet in diameter) and are operated through computers in a control room. Some telescopes are even set up so that they can be controlled remotely over the internet by observers sitting hundreds of miles away.
When astronomers point a telescope toward a particular celestial object of their interest, they capture its image by exposing a charged-coupled device, or CCD, attached to the telescope. When light strikes the CCD, it dislodges electrons in the CCD's material. At the end of the exposure, the number of dislodged electrons in each pixel is read out to tell us how much light hit each particular pixel of the CCD. This digital signal is then turned into a black and white picture of the object the telescope is pointed toward. In order to get the really beautiful pictures we share with the public of celestial objects, astronomers must take pictures of the same object in a variety of wavelengths or bands that correspond to the colors seen by human eyes. We then carefully combine each of the photographs to produce the high quality images everyone loves to see.
Q: How big of a deal is this upcoming eclipse to astronomers? What do they hope to learn from it?
A: Many astronomers have never seen a total solar eclipse so seeing the corona of the sun during totality will be just as majestic for those who study space for a living as everyone else who stands in the shadow of the moon on Aug. 21.
One question that astronomers will try to answer by studying the solar eclipse is what heats the outer layers of our star. Heat naturally flows from warmer to cooler places. The temperature of our sun decreases from tens of millions of degrees in the interior to about 10,000 degrees on its surface. By the laws of nature, we then expect the temperature to decrease as we move into the sun's atmosphere. However, the temperature rises to over 2 million degrees in the corona so there must be some additional heating process within the solar atmosphere that we do not completely understand yet. Astronomers can only see how the behavior of the atmosphere where it meets the surface of the sun during total solar eclipses so there are not many opportunities to do this type of science.
There are a number of amazing citizen science projects that involve atmospheric physics and biological sciences that everyone can participate in on Aug. 21. A rundown of these projects is featured here.
Q: How is the astronomer pipeline? Are there as many students today as interested in entering the field as earlier during the space race and shuttle era?
A: There are slightly more physics degrees conferred today as compared to the space race era and the number is on the rise. Watching men walk on the moon inspired an entire generation of people and I hope that witnessing something as awe-inspiring as a solar eclipse in your own backyard will enlighten the next generation to pursue STEM (science, technology, engineering, and mathematics) careers.
As our global need for technology grows every day, we need Americans who are well prepared to lead us into the future. Majoring in science fields like astronomy and physics can lead you down many career paths. Astronomers are taught how to think outside of the box, to have healthy levels of skepticism because they become great critical thinkers, and to break big problems into solvable pieces. So not everyone who majors in astronomy may continue to answer questions about space, but they may also crunch numbers as data scientists, write code as computer programmers, or be innovative at tech companies. The small skills learned along the way to understanding our big universe can add up to success in a variety of careers.
Q: And, finally, early in the interview you mentioned the three-dimensional shape of exploding stars in distant galaxies. Why is it important to study that?
A: When supernovae are detected in distant galaxies, the explosions look like bright points of light, like brand new stars, that appeared in the galaxy seemingly overnight. These explosions are so bright that they can sometimes outshine the light of the entire galaxy where the star lived for billions of years. I study explosions that originate within burned out cores of stars called white dwarfs. These white dwarfs all explode at nearly the same mass and therefore are all equally bright explosions. However, by comparing how much a white dwarf's brightness dims to how bright we know it should be, we can determine the distance to that supernova and therefore to its host galaxy. Astronomers have used these white dwarf explosions, called Type Ia supernovae, to measure the distances to galaxies billions of light-years away. The results have shown us that our universe is expanding and the expansion is accelerating with time.
In order to determine the accelerated rate more precisely, we must carefully study the intrinsic brightness of the Type Ia supernovae. That's where my work on measuring the three-dimensional shape of these explosion comes in. Our precise measurements of these explosions show that they are not perfectly round, and therefore the angle at which you view the explosion can change how bright you measure it to be. As an exaggerated example, imagine the ejecta of an exploded star takes on the shape of an egg rather than a baseball. The explosion will not appear as bright if you view the egg's top as compared to the egg's side. My quest is to measure the three-dimensional shape of Type Ia supernovae so that we can measure the distances to their galaxies more precisely.