If you have spent much time in E. Bronson Ingram residential college on Vanderbilt’s campus, you may have noticed that part of the dorm is named after one Edward Emerson Barnard. As it turns out, Barnard was an astronomer who attended the university from 1883-1887. His research focused on observation and photography of stars and other celestial objects in the night sky and he is credited for a number of comets, among other things.
In 1892, Barnard discovered Jupiter’s fifth satellite moon, Amalthea. This was the first of Jupiter’s satellites to be discovered since time of Galileo, which is pretty remarkable. Barnard also discovered a star displaying considerable proper motion (its one of the closest stars to us) in 1916 which is named after him. Combining his interest in photography with astronomical observation, Barnard helped to progress our knowledge of the Milky Way and our solar system within it.
In Saint John, New Brunswick, Canada, 100 billion tons of water flow in and out of the Bay of Fundy each day by way of the Saint John River. Yes, in and out of the same river. The water level of the Bay of Fundy changes a dramatic 28 feet between low and high tide. This nearly 10 meter change results in a “reverse falls:” the rapids run towards the bay at low tide, but move back up the rapids at high tide. As we know, tides are caused by the gravitational force of the sun and moon on Earth’s bodies of water. As such, we can deduce that the high tides on the rapids coincide with periods where Earth rotation positions New Brunswicks is towards the moon, while low tide coincides with when the moon is on the opposite side of Earth as New Brunswick. The bay reaches extremely high tides when the moon is in full or new moon. This leads the rate of water backflow in the river to exceed 100 billions tons of water, greater than the volume of every river on earth.
The relationship between color, energy, frequency, and wavelength!
A prism splits white light into a spectrum of colors ranging from red to violet. These colors correspond to different wavelengths, frequencies, and energy levels. Light with a longer wavelength has a lower frequency and lower energy level, and light with a shorter wavelength has a higher frequency and higher energy level. Violet light has a relatively shorter wavelength and higher frequency compared to other types of visible light. Red light has a relatively longer wavelength and lower frequency, so it is lower energy than violet light.
Wavelength and frequency correspond to energy level and are meaningful in understanding how photons are emitted from and absorbed by atoms. If an atom absorbed violet light photons, it would gain a relatively large amount of energy and its electrons would move to higher energy levels. On a spectrum, we would see black absorption lines where violet would be. If an atom released violet light photons, its electrons would fall to lower energy levels. If an atom absorbed red light photons, it would gain less energy than if it absorbed violet. The electrons of the atom absorbing red light would not be able to move up as many energy levels compared to the electrons in the atom absorbing violet light.
Do you all think radio waves or x rays have more energy? Why?
Light is a weird thing. It is both a particle and a wave, yet it has no mass to it. This means it should be immune to certain laws of physics, such as gravity, since gravity requires two masses to generate a force. However, light does bend due to gravity. This is not the normal attraction, but rather the bending of the fabric of space itself. This curvature of space due to the presence of a massive object bends light towards the center of the massive object. The heavier the mass is, the more the light curves.
During total eclipses of the sun, the light of the sun is blocked out for a while, allowing one to observe the sky with the stars and planets during the day. One interesting phenomenon was that some bodies were spotted during this time and became visible to Earth, even if they were located directly behind the Sun.
Visualization of the bending of the light towards the sun, credit to Discover Magazine
This visual proof shows how the mass of objects bend light. With more massive objects, the larger the curve.
Newton, Kepler, Galileo, Copernicus… Eratosthenes?? The name Eratosthenes is not as universally renowned, or even as known, as the likes of Newton or Galileo.; however, his contributions are just as exceptional. More than 2200 years ago, around 240 B.C.E, Eratosthenes correctly measured the circumference of the Earth to within 5% of its correct value. Considering the rudimentary tools and relatively minimal preexisting knowledge that he had to work with, this feat is one of the most impressive in the history of astronomy. Furthermore, Eratosthenes made his remarkable calculation using only relatively basic geometry and astronomical knowledge. Eratosthenes knew that during the summer solstice, the city of Syene observe the Sun at the zenith (altitude = 90 degrees). On the same summer solstice, Eratosthenes measured the sun to be at an altitude of 83 degrees in his home of Alexandria. Because the Sun is at a great distance from Earth, the Sun’s rays that hit Alexandria and Syene are virtually parallel, and so Eratosthenes concluded that Alexandria was separated from Syene by 7 degrees of latitude. Eratosthenes knew that the north-south distance from Syene to Alexandria was approximately 5000 stadia (or 833 km), and so he calculated that 7 degrees of arc subtends 5000 stadia north-south. Eratosthenes measurements led to his conclusion that Earth was approximately 250,000 stadia or 42,000 km in circumference. In the 21st century, humans use satellites to measure Earth’s circumference. This method yields an (average) circumference of close to 40,000 km, just 2,000 km different from the value that a single person with a wooden stick calculated more than 2,000 years prior.
Hypatia is considered the first female astronomer and mathematician (of whom we have records) of the world. She lived in Alexandria in the 4th century AD, where she studied and taught philosophy and astronomy at the Neoplatonic school of Alexandria. Her father, Theon of Alexandria, was a prominent mathematician and some consider him the last member of the Library of Alexandria. The two of them worked together to edit Ptolemy’s Almagest, a mathematical and astronomical text covering the motions of the planets and stars using a geocentric model. She is also known to have built astrolabes, astronomical instruments used to calculate astronomical positions. Later in her life, she advised Orestes, a Roman state official who was feuding with Cyril, the Christian bishop of Alexandria. As a result of this conflict, a mob of Christians brutally murdered Hypatia. Some historians believe that the destruction of the Library of Alexandria, an archive of history and research, coincided with her death.
In the television show Avatar: The Last Airbender, the main character is able to commune with one of his past lives on the Winter Solstice. This happens when the sun shines through the wall and directly hits a statue of the past life that he is trying to talk to. The catch in the show is that the sun only shines on the statue once a year, during the Winter Solstice.
As seen above, the Sun perfectly aligns itself with the arches of Stonehenge during the Summer Solstice. This is just one of many real-world examples of cultures building monuments around solar events, just like they did in Avatar. The Scottish were far from the only culture to find a way to commemorate the Winter Solstice; in fact, it has significance in almost every single culture.
This Irish tomb allows light in for a few minutes on the Winter Solstice. This tomb was thought to have accompanied celebrations of life as they saw the solstice as the death and then rebirth of the sun.
Spectroscopy is the information that comes from a spectrum. The spectra of an object tell us the electrical electromagnetic radiation, the chemical composition, and the wavelength of an object. Each type of molecule and atom will react to the electromagnetic radiation in a different way. One type of spectroscopy, absorption spectroscopy , the light is absorbed by molecules and changes energy states A detector records the depth and the absorption of wavelengths. This is known as a absorption spectrum.
The topic of light in regards to astronomy or any study of space is incredibly fascinating. In a vacuum, the speed of light travels around 300,000 km/sec and is known to be the fastest phenomenon in the entire universe. There’s so many interesting aspects that come out of studying light. One such example would be that the closer an object moves to the speed of light, the slower time becomes for that object. It is even believed that if we were to create a vessel that travels faster than the speed of light, time travel would be possible. Now as crazy and captivating as that sounds, it is not even the most interesting thing about it. In fact, in a far more practical sense, we as humans can experience “time travel” every day in everything we see. If you are ever to stare out into the night sky, you are looking at the stars, moon, sun, and planets in the past as takes time for light to reach us. Yes, even despite how quickly light moves, there is still calculable times that it can take light to reach us from a certain distance. And this is where the idea of looking into the past comes into play. When we stare at the sun for example, there is roughly an 8-minute time gap for the sun’s light to reach us. Essentially what is occurring is us seeing the sun 8 minutes in the past. Even when we look at the moon, there is roughly a one-minute gap until its light reaches our eyes. The thought of peering out at something and only ever seeing it as it once existed moments, minutes, hours, or years ago in the case of other stars in the galaxy, is simply so enthralling. Moreover, even when you look at your friends in person, you are only seeing them in the past as it still takes time for the light from them to reach your eyes. If you stare at your feet you are still viewing it from the past. Of course due to its immense speed to the time buffer is unnoticeable and infinitesimally small, but the concept still remains true. Anything we ever see is still technically a past version of it, which is why I think this aspect of studying light is the most interesting and remarkable of them all.
