People generally don’t think about how the moon impacts surfing, but there’s actually a close relationship between the two. The conditions at beaches change a lot depending on the tidal stage, which is itself determined by the position of the moon relative to the Earth. As the Earth spins, two bulges form on the surface, one on the side of the moon, and the other on the opposite side. These two bulges constantly chase each other, causing tides.
http://www.surfingcal.com/tides.html
I always wondered how we were able to determine what chemicals are present in other stars in outer space. This video excellently and concisely teaches the basics behind studying this in terms of spectroscopy. Naturally, light is important in our viewing of the stars, but I never considered that the way different elements bend light could be used in astronomy. It is so cool that they can detect these patterns in stars that are so distant from us.
There is a special telescope located in Antarctica accurately called the IceCube that has a very specific task. The IceCube is supposed to find neutrinos. Neutrinos are high-energy subatomic particles that are supposedly made from tremendously energetic events far extremely far away from us. These neutrinos have “more than a 1,000 times the energy of protons smashed at CERN’s Large Hadron Collider.” However, neutrinos basically pass through everything without any interactions. Every once in a while they collide with a molecule and produce a blue spark. The IceCube has thousands of light detectors located 1.5 kilometers bellow the surface of Antartica. These light detectors collect data from these blue sparks, which can hopefully be used later to determine the origins of these elusive particles.
When I first heard the term 30-meter telescope I was quite confused. Did this mean that the telescope is 30 meters long? Does this mean that the telescope is powerful? Based on the size of the telescope in the image above it is clear that the telescope is powerful. The 30-meters refers to the length of the aperture. The aperture allows us to focus more by diffracting light. The aperture is the diameter of the main lens or mirror. This controls the brightness and sharpness of images. All things being equal, the larger the aperture the more accurate the image. When this telescope is completed, it will allow us to make more clear observations of the cosmos. This is exciting for professional and amateur astronomers alike.
There are over 1500 near earth asteroids that are being considered by Planetary Resources and other companies like it and virtually all of them contain things of value. Whether it is the raw materials for fuel and construction, or precious metals that outsize the current stores on earth, asteroids have the greatest promise for making space more accessible by taking the launch out of the equation for many vital resources. This may sound like a science fiction initiative but the first missions are right around the corner. Mission launches are set to begin prospecting asteroids for their size shape and composition as early as 2016. The estimated wealth available on asteroids is estimated in the trillions. Planetary Resources
There are many problems that earth-based telescopes must cope with. Besides light pollution, the largest one is dealing with distortion that is caused by turbulence in the earth’s atmosphere.
Compare looking at an object at the bottom of a still pool and a pool with many waves. When there are waves, the image is distorted because the light is refracted, distorting your clear view of the bottom. This in essence is what happens when light comes through the atmosphere to us.
Atmospheric turbulence distorts how we perceive astronomical objects. Any images we take will come back blurred. To the naked eye, turbulence manifests itself in the twinkling of stars. The distance of the object is important as well – distant objects will dance around. Closer objects will not, which is why planets don’t twinkle.
Light is refracted in many directions as it travels to the ground. It must travel through air of various and constantly changing densities and temperatures, so this changes the atmosphere’s light-bending properties. Light reaches a telescope at slightly different angles and times, which creates multiple images of an object. Ultimately, this mean’s that a telescope cannot be used to its full potential – their diffraction limit. The diffraction limit is the smallest angle that something can discern two different objects. People have a diffraction limit of about 1 arminute. Large telescopes usually can have a diffraction limit of 0.05 arcminute. With turbulence, however, sometimes telescopes might only be able to discern 2-3 arcminutes – a significant difference!
However, to compensate for the issue, a technology known as adaptive optics have been created to reduce the blurring. This greatly helps the telescope reach close to its diffraction limit. Speckle interferometry is also a method of limiting distortion by taking several fast exposures of an object. Because each exposure is so fast, the images freeze the motion of whatever is being observed. These images are then organized by a computer to build an image without distortion.
Have you ever heard an ambulance fly by you and noticed that the pitch changes as it approaches you, and changes again when it goes past you? This phenomenon is known as the Doppler effect (or Doppler shift). What happens is that as the ambulance approaches you, each of its successive sound waves are emitted closer to you, which raises the frequency (or pitch) of the sound. When it recedes from you, the sound wave is emitted further from you, which deceases the frequency and pitch of the sound.
Interestingly, the use of the Doppler effect is not limited only to the world of sound, but to almost everywhere where any kind of wave is involved. The same shift in sound waves seen above is also applicable to light waves, since light acts as a wave and as a particle.
In astronomy, the use of the Doppler effect is used to measure the speed at which stars and galaxies move relative to us. It doesn’t tell us the exact speed, but informs us of their radial velocity.
For example, if a star is moving toward us, light waves will get “bunched up” as it approaches and the light’s frequency will increase. This is known as blueshift because in the visible color spectrum, light with increased frequency will become bluer. If the star is moving away from us, the light waves will get spread out and the frequency will decrease and a redshift will occur. In the visible color spectrum, light of less frequency approaches red, which is the color of lowest frequency.
However, blueshift and redshift is not only related to the visible color spectrum. Astronomers use the terms in any kind of color spectrum, since they are useful for describing whether or not light waves are increasing or decreasing in frequency.
If you were to summarize the most important lesson taught throughout Chapters 3-6, the most overarching theme to take note of would have to be the conservation laws that exist throughout our universe. The conservation of momentum, angular momentum and energy are all vital laws of physics, and rather than studying these each independently, in Chapter 4 we learn their relationship to one another, and how they support subsequent laws of physics such as Newton’s three laws and the concept of gravity.
As we look at the “big picture” of astronomy, the conservation laws depict the basis of our understanding of the universe. Without them, everything that we have come to observe and define in astronomy loses its meaning. These three laws work towards furthering our comprehension of orbits, potential energy and kinetic energy, and without these main principles, the concept of physics would simply not exist.
Generally, if you’ve ever been on the ocean, you understand the concept of tides. You put your umbrella and chair up at noon near the edge of the ocean and you fall asleep and you wake up a few hours later in the middle of the waves. You didn’t move, so the ocean had to have been the one to move, right? These are considered the high and low tides that are experienced twice daily. They are caused by the moon’s pulling on the Earth’s water (causing bulges). These high tides are about 12 hours and 25 minutes apart. If you want to see a great example of high and low tides, check this time-lapse video of the Bay of Fundy.
Now, even though we experience high and low tides every day, the moon also causes spring and neap tides.
The above photo shows how the cycles of the moon correspond to the spring and neap tides. Spring tides are the strongest because they combine the moon and sun’s gravitational pull and they occur on new and full moons. The neap tides are very weak and occur when the moon and sun are perpendicular to each other. So, the next time you are at the beach for a week, check out the tides so you know where to put your chair!
As we study the history of astronomy, and delve into the lives of figures such as Newton, Kepler and Capernicus, I found it particularly interesting how vital the Christian Church was in proving/disproving whether the so-called “scientific facts” of the time could be accepted by the common people. Above all the other readings, what struck my attention most was the section detailing the latter half of Galileo’s life, and how above all his observations, his most meaningful discovery seemed to be the “imperfections” he saw in the Sun – specifically, the fact that the star had sunspots. This notion that the “heavens” could hold such an imperfection (that also existed on the Earth and Moon) was significant in considering the idea of the Earth’s elliptical orbit about the Sun, rather than the perfect, celestial sphere that other astronomers of the time held so dearly to their scientific model. Here, we can clearly see the context of history in which Galileo lived his life, and the difficulty astronomers of the time faced with consideration of the church.
