The Sun’s photosphere extends near its surface, in the region where the gas becomes opaque, with an optical depth of up to 400 kilometers. Despite the light emitted, the photosphere is one of the coolest regions in the Sun’s atmosphere with a temperature of about 6000 K. This region is also the densest part of the solar atmosphere but still incomparable to Earth’s atmosphere. At a closer look, the photosphere is comprised of convection cells known as granules, which are gas cells with a diameter of about 1000 kilometers with a life span of about eight minutes, following a continuous boiling pattern. This region in the solar atmosphere often appears as dark specks called sunspots, which is caused by the Sun’s magnetic field.

Other astronomical bodies have a photosphere like the Sun. This region in an astronomical body’s atmosphere is often the deepest, which is transparent for photons in different wavelength of the electromagnetic spectrum. The photosphere is a visual description of the Sun’s or another star’s surface.

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Light polarization, for one, is considered to be an essential phenomenon in this particular field of science. The much observed polarization of starlight gave way to the development of theories that use polarization data in tracing interstellar magnetic fields, thus furthering studies of astronomical objects way beyond our solar system.

Polarization has also given way to the study of the cosmic microwave background or CMB. This refers to the thermal radiation that uniformly spreads across the universe. CMB is essential to the study of the beginnings and earlier characteristics of our universe.

In the observation of extended astronomical objects like reflection nebulae, optical polarization can provide data on their nature, structure and even their dust content. The measurements of both the circular and linear polarizations of light waves coming form the Sun has also given scientists more information towards a much deeper understanding of the components of our very own star, its activities as well as its possible life span.

Polarization can also provide scientists with information on the various sources of radiation and scattering. This can be observed in both coherent and incoherent sources in interstellar space. Coherent radiation is capable of interference, while incoherent once tend to produce electromagnetic waves on its own.

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A shock wave is characterized by the sudden and nearly discontinuous change within different mediums.

It is caused by the tremendous rapid rise in temperature, pressure, or even with the density of the flow in the atmosphere. In a conventional supersonic flow, the expansion is attained through expansion fans.

Shockwaves always travel at much higher speeds when compared to the usual, ordinary wave. Unlike other kinds of non-linear waves, the shock wave’s energy disperses quickly as it travels. However, the approach of the accompanying expansion wave partially cancels out the energy as it merges with the shock wave. This is what causes the sonic boom which comes with the passage of any supersonic aircraft through the sound wave that results in a expansion wave merger.

Physically, shockwaves in the air are typically heard of as that loud snap or cracking noise. And over long distances, shockwaves can naturally change from non-linear waves into linear waves. This then degenerates into a sound wave conventionally as it reacts to its surroundings, heating the surrounding air thereby losing the energy. This sound wave is the normal thump or thud of the sonic boom that is commonly created in flight of a supersonic aircraft.

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Photovoltaic (PV) utilizes solar cells, which are often embedded in the solar panels to capture the energy coming from the Sun. Energy is created when these solar cells are continuously exposed to light, specifically to sunlight, exhibiting the photovoltaic effect. When this is in progress, the photons are excited or pushed into a higher energy state to produce electricity. Photodiodes are responsible for the unbiased operation in photovoltaic devices where power is produced entirely by the transduced light energy. The growing demand for renewable energy resources have resulted to the drastic developments and innovations in photovoltaic reserach (PV), resulting in more sophisticated and high quality solar panels.

These solar panels must be resilient to the wear and tear caused by the changing environmental conditions. Most solar panels today are protected by glass sheets to ensure the efficiency of the solar cells and the optimum photovoltaic (PV). With the Sun’s significant role on Earth, the light it emits has limitless possibilities for practical day-to-day usage.

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Most dictionaries would define the term as the process of energy (either in rays or waves) emission from a source. In physics, it is a process by which energized particles travel through space or another medium. There are different types of radiation of which the emission of energy from radioactive substances such as uranium is one; however, what is important in astronomy and the study of space is electromagnetic radiation. Under electromagnetic radiation, there are also several types from gamma rays, infrared radiation, radio waves, microwaves, synchrotron radiation, and many others.

The discovery of electromagnetic radiation began with James Clerk Maxwell. He postulated that light is composed of electromagnetic waves. However, his theory had many loopholes. It was not until Max Planck’s quanta of radiation that the phenomenon was viewed clearly. He proposed that the absorption and emission of radiation occur in fixed units of energy referred to as quanta. Later, Albert Einstein shed light into the process when he proposed that electromagnetic radiation behaved similarly with particles, which forms the foundation of what people know today about radiation.

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One of the topics not commonly tackled when talking about momentum is radiation pressure. Another name for radiation pressure is light pressure since it refers to the force exerted by an individual photon (usually a quantum of visible light but can also pertain to any other type of electromagnetic radiation). With momentum being a property of most objects, it is not surprising that even a small photon can possess such characteristics. In fact, the photon might not have mass or electrical charge but has energy and momentum. This is where it becomes complicated because if momentum is computed by multiplying the mass of an object by its velocity, how can a photon that does not have mass, have momentum?

The answer: because it is momentum that actually determines the amount of pressure or force that a particular object exerts on a surface, even photons that technically do not have mass can be said to have such property. However, instead of referring to the force exerted by the photon as momentum, it is called pressure; thus, the use of the term radiation pressure with radiation referring to electromagnetic radiation. Technically, radiation pressure is the pressure exerted on any surface that is exposed to electromagnetic radiation.

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Photo by: ESO Creative Commons

What do Christian Doppler and Albert Einstein have in common? Simple, they are both instrumental in weather forecasting through their contributions to the information people know about radial velocity. Without understanding how radial velocity works, warnings about tornadoes and hurricanes are not possible.

By simple definition, radial velocity refers to the speed of any object in the direction of an unmoving observer’s line of sight. This can pertain to directions of either moving toward or away from the observer. In a three dimensional space, radial velocity can apply to any object with respect to the observer since the position of the observer remains fixed. However, radial velocity best applies to celestial bodies such as planets.

Planets have two types of velocities. As the planet moves away from the observer when orbiting toward the far side of sun, it is said to have a positive radial velocity. On the other hand, when the planet moves from the far side of the sun toward the observer it is now said to have negative velocity.

This is also where the Doppler shift comes into play. Astronomers observing orbiting bodies use data in the form of electromagnetic waves detectable from telescopes. The Doppler shift is seen as electromagnetic waves are compressed and possess a higher frequency when objects move toward the observer and change into a lower frequency when moving away from the observer.
Aside from using radial velocity to gauge the orbital cycle of planets, it can also be used to indicate the rotational movement of storms.

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Observed gamma ray burst is outside Milky Way. There are theories that if a gamma ray burst would occur in Milky Way, there would probably be a mass extinction in earth.

Gamma ray burst is first detected using satellites designed to sense nuclear weapon tests. These are US military satellites searching for Soviet?s nuclear testing in the atmosphere. A nuclear explosion can emit gamma rays. These satellites have gamma ray detectors and then that?s how gamma ray burst was discovered.

There are two classifications of gamma ray bursts. The long gamma ray bursts and the short gamma rays. They are classified based on the duration of the bursts. The long gamma ray bursts that lasts from two seconds or more and the short gamma ray that lasts in less than two seconds.

Gamma Ray Burst (GRB)

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The small field found at the wide range of frequencies of electromagnetic radiation is called visible light. It can be discerned by the naked eye and has wavelengths measured to be from 780 nanometers to 390 nanometers. Each wavelength has a particular color and when that specific wavelength hits one’s eyes, one perceives or identifies the color of that wavelength. For instance, what makes a green leaf green is because of the specific wavelength of the visible light coming from the leaf.

Visible light is comprised of different colors. They are the colors found in the rainbow. When the light that comes from the sun hits water, it reflects the different colors or wavelengths. This separation of the visible light into various colors is known as dispersion. These colors are red, orange, yellow, green, blue, and violet. Red is the longest wavelength while violet is the shortest one.

There are gadgets and devices made for people to comprehend and appreciate the concept and qualities of visible light. These devices are prisms, mirror, spectrometers, lenses and diffraction gratings. When you allow light to pass through a prism, you will see it being separated into the different wavelengths or colors it possesses.

Without visible light, things or objects cannot be illuminated and we will not be able to see and appreciate them. We will not distinguish the colors that add beauty to a certain thing. The source of the visible light is the sun. When you see white light, you do not see one specific color but actually a combination of the different colors mixed together.

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Gamma ray

All ionizing radiation can cause damage at a cellular level. Gamma rays penetrate and can cause severe and scattered damages throughout the body. Examples would be radiation sickness and cancer.

Gamma rays can kill living cells that?s why it is used widely in sterilizing medical instruments. The process is called irradiation. It can also be used to remove bacteria from foods and prevent fruit and vegetables to sprout to keep its flavor and freshness.

Though gamma rays have properties that may cause cancer, it can also be used to treat some types of cancer. It can be used to kill the cancer cells, and the process is known as the gamma-knife surgery where its beams are directed on the cancer growth.

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