Humans can only see a limited range of all of the light that is in the universe. As learned in class, there is UV, radio, infrared, and Gamma ray waves. The light we can see is a small portion between the UV and infrared waves, but other animals rely on their ability to see light which we cannot. Bees are able to see Ultraviolet light which is reflected by flowers containing nectar, and snakes are able to see infrared light which is produced by anything that produces heat. These abilities to see more light is necessary for survival. Attached to this post is an image of what it is like to perceive infrared light, more details on the subject can be found here. Animals also have different levels of visual acuity which is the ability to see details. If a frog were to look at a page of a book, it would only see a gray blob. I think it is very interesting to note that every species sees the world in a different light, quite literally.
Johannes Hevelius observing with one of his telescopes.
The telescope was first invented in the Netherlands in 1608. Its design quickly spread across Europe until it reached Galileo. Galileo spent years refining and redeveloping the telescope until it was much more powerful than before. He was able to observe many new astronomical phenomena such as the moons of Jupiter. For a while, Galileo had the best telescopes in the world, but many people began to build their own telescopes of similar quality. The technology continued to develop throughout Europe and led to many more astronomical discoveries such as the phases of Venus.
The next major innovation was the reflecting telescope, which used curved mirrors as well as lenses to magnify the images even more than before. This technology was used all the way into the 20th century. Eventually, scientists started to use other types of telescopes to collect more detailed information about the universe. Radio, infrared, ultraviolet, x-ray, and gamma ray telescopes were all invented in the mid 19th century and are used to collect information related to other types of non-visual light. While these telescopes don’t provide visual pictures of the phenomena in our universe, they provide scientists with crucial information about the chemical compositions of stars and planets. These telescopes were used to discover Cosmic Microwave Background Radiation, which was previously undetectable by visual light telescopes.
Have you ever been fishing? If you have, you probably know that your success partially depends on whether the ocean experiences a low tide or a high tide. But do you know the science behind what causes tides? Below is a quick and simple explanation why.
Tides are caused by differential gravity. We know from Newton’s universal law of gravitation that any two objects with mass exert an attractive force on each other. This holds true for large masses too, like the Earth and the Moon. The Moon exerts a gravitational force on Earth, but the magnitude of this force differs for different parts of the Earth. The side of the Earth closer to the Moon experiences more force than the side that’s farther from the Moon, which causes differential gravity. Certain sides of the Earth, in response, bulge out, which causes high tides.
From Earth, the Sun appears to be just a glowing yellow orb. However, the Daniel K. Inouye Solar Telescope in Hawaii has captured new images of the Sun that reveal its violent and explosive nature. This massive four-meter telescope has the technological capabilities that are necessary to better understand the Sun’s magnetic field and outer atmosphere. The large aperture allows for greater resolution than any other solar telescope, meaning we can see clearer images than ever before. The image above was captured by this telescope. The large cells of burning plasma are visible in incredible detail. The bright centers and darker edges of these Texas-sized demonstrate the dynamic and raging motion of the Sun’s surface. Going into the future, the information collected from this telescope will spur new discoveries and a better understanding of the Sun and its impact on the solar system.
Stromatolites are layered mounds or sheet-like layers of sedimentary rock that were originally forced by growing on a layer of cyanobacteria, a single-cell microbe. Fossilized stromatolites provide a record of ancient life and tidal patterns on Earth.
Millions of years ago, seas all over the world would resemble the picture above, which was taken from Shark Bay, Australia. This unique pattern was created through a process of accumulation of calcium carbonate and the depletion of carbon dioxide in the water.
Cyanobacteria, which resulted in the creation of stromatolites, were one of the first organisms on Earth. Certain kinds of cyanobacteria are 3.7 billion years old. They produced oxygen as a by-product of photosynthesis, which made it possible for more complex life forms to evolve in our oceans.
Researchers at the Astronomical Observatory of the University of Warsaw have recently discovered two previously invisible stars deep within the Milky Way. These binary stars (two stars that effectively orbit each other) were found thanks to a star called Gaia16aye that is considerably farther away. A few years ago, astronomers noticed that Gaia16aye would occasionally “flash” for a day or so and then go back to its normal brightness without initiating a supernova. It wasn’t until this past January that it was determined that these flashes were due to gravitational lensing from the aforementioned binary stars that are not bright enough to be seen from Earth. Although dim, these two stars are still massive enough to create multiple pockets of magnification that allow us to get a brighter look at Gaia16aye. Even though they are completely invisible to us, scientists are still able to determine almost everything about them thanks to the effects of gravitational lensing. This is exciting news because if gravitational lensing events like this one can show previously invisible stars, astronomers might be able to uncover even sweeter scores (like black holes) within our very own Milky Way galaxy. Space, baby!
Three weeks ago, for my Earth System Dynamics course, I listened to a Radiolab podcast about the distance between the Earth and the Moon. In “The Times They Are a Changin'” paleontologists talk about how coral shells taught us that the Earth used to have shorter days. Their shells have tiny bands, an alternating pattern of stripes, that have tiny lines in them, each of which records a day. Paleontologists first noticed that living corals each have 365 little lines in the bands on their shells. These shells are basically little calendars and clocks. When paleontologists went back to investigate how many of these little lines were on corals from the Ordovician Era, 450 million years ago, they found that there were over 415 little lines, meaning there were 415 days in the year. The Earth has not been speeding up around the Sun, slowing down our years. Instead, the days have been getting longer. The “celestial waltz” between the Earth and the Moon is the reason our planet spins slower than it once did. It’s the reason we have the 24-hour days we are accustomed to. Since the Earth is rotating faster than the Moon is orbiting it, the Earth tugs the Moon along and the Moon tugs the Earth back, slowing it down. This means that each day is 54-billionths of a second longer than the day before it. That means today is the shortest day of your life!
A rendering of a “coral moon” by WNYC’s Sahar Baharloo
Why does this matter? The Earth isn’t slowing enough to really affect me. The day I die will be only a few seconds longer the day I was born. But taking a step back, it helps me appreciate the delicate balance that allowed me to get here. All of the things that we take for granted about our planet that allow us to live here are constantly changing. Around the time that the first creatures moved out of the water and onto land (almost 400 million years ago), the Moon was a lot closer. That means that the tides would have been much more dramatic. Perhaps having much larger tides would have helped sea creatures make their way ashore. Perhaps it is the case that without the 415-day year the ancestors that led humans ashore would have never been able to get out of the comfort of the oceans. If it weren’t for the proximity of the Moon hundreds of millions of years ago would we be mermaids instead of humans? We’ll never know, but it is always nice to think of how many different things had to go exactly the way they did in order for us to be alive today.
If you found this topic interesting, check out another Radiolab podcast, “The Distance of the Moon,” in which actor Liev Schreiber reads a story written by Italo Calvino and telling of a time that the Moon was so close to the Earth that you could jump back and forth between the two. Thanks for reading!
Gravity exerts a force on photons, even though it has no mass. This can distort the things we see if the light that reaches us is being distorted by gravity, as seen in the picture at the top of this post. The confusing aspect of this is that gravity affects this light even though the light has no mass. This is explained in Einstein’s Theory of Special Relativity that gravity is not pulling the light, but it is rather changing the geometry and physical laws of time and space around it. This means that the light that is affected by gravity is still moving in a straight line, but the planet or other massive object whose gravity is affecting it is changing what a straight line is. Also, rather than accelerating on its path when affected by gravity, light just changes in its frequency, because it always moves at a constant speed that does not change. This is what causes the blue shift and red shift in light. When moving towards the massive object, there would be a blue shift in the light because the frequency would increase, and if moving away from the massive object, there would be a red shift. Here is a video explaining this in more detail and here is the link to the picture.
Throughout this unit, we learned about tides, their causes and what influences them. In preparing for this blogpost, I came across two different kinds of tides (besides high and low tide) called “spring” and “neap” tides. These tides correlate with the moon phases, in that spring tides occur during the new or full moon, and the neap tides 7 days after the spring tides.
Spring tides are more extreme in their difference between high and low tide. This occurs when the Sun, Moon, and Earth are more or less aligned, and thus the gravitational pull of the Sun and Moon are “added”, creating higher high tides and lower low tides. Neap tides refers to when the Sun and Moon are at right angles to each other, canceling out each others pull a little bit, creating a lower high tide and a higher low tide; the tides are less extreme in their differences between each other.
Tides are caused by differences in magnitude between the gravitational pull on the near and far side of the Earth by the Sun and the Moon. The face of the Earth closer to the Sun or the Moon receives stronger gravitational pull and the far side receives weaker gravitational pull, so the oceans on the side of the Earth facing the Moon and the opposite side of the Earth bulge outward at the same time when there is a tide. Since the Sun and the Moon both exert gravitational forces on the Earth, they both cause tides on Earth and their forces add up to cause high and low tides. When the Earth, the Moon and the Sun line up, we see high tides on the Earth. When the Moon and the Sun form a 90-degree angle around the Earth, their forces don’t add up at all and we see low tides. Obviously, we will see high tides during the full Moon and the new Moon, when the Moon has elongation angles of 0 degree and 180 degrees. Therefore, though people refer to high tides as “spring tides”, high tides take place biweekly instead of happening only during springs.
Another interesting point I want to share from my outside research is the Earth’s land surfaces are also affected by tides. They can move up to 55 centimeters a day when a high tide occurs! We may feel the land unmoved, but the whole surface is shifting dramatically. This phenomenon is referred to as “terrestrial tides”. Volcanologists care about it because such shifts sometimes cause volcanic eruptions.
