SCIENCE IN UNIVERSE

Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea. Out in the depths of the ocean, tsunami waves do not dramatically increase in height. But as the waves travel inland, they build up to higher and higher heights as the depth of the ocean decreases. The speed of tsunami waves depends on ocean depth rather than the distance from the source of the wave. Tsunami waves may travel as fast as jet planes over deep waters, only slowing down when reaching shallow waters. While tsunamis are often referred to as tidal waves, this name is discouraged by oceanographers because tides have little to do with these giant waves. YouTube Link  -  https://www.youtube.com/watch?v=Wx9vPv-T51I Credits -  https://oceanservice.noaa.gov/facts/tsunami.html Picture Credits - To the rightful owner

X-rays are a form of electromagnetic radiation, as are radio waves, infrared radiation, visible light, ultraviolet radiation and microwaves. One of the most common and beneficial uses of X-rays is for medical imaging. X-rays are also used in treating cancer and in exploring the cosmos.  Electromagnetic radiation is transmitted in waves or particles at different wavelengths and frequencies. This broad range of wavelengths is known as the electromagnetic spectrum. The EM spectrum is generally divided into seven regions in order of decreasing wavelength and increasing energy and frequency. The common designations are: radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays and gamma-rays.  YouTube Link  -  https://www.youtube.com/watch?v=oM_-FnjNTwA Credits -  https://www.livescience.com/32344-what-are-x-rays.html Picture Credits - To the rightful owner

Dry Ice is the common name for solid carbon dioxide (CO2). It gets this name because it does not melt into a liquid when heated; instead, it changes directly into a gas (This process is known as sublimation). As Ireland’s premier dry ice specialist, Polar Ice provides dry ice solutions for a diverse range of customers, in areas such as: Hospitals & Clinics Food Processing & Distribution Industrial Cleaning and Technical Processes Theatrical and Special Effects YouTube Link  -  https://www.youtube.com/watch?v=kEbwxFinuEs Credits -  https://dryice.ie/what-is-dry-ice/ Picture Credits - To the rightful owner

The Dead Sea has the lowest elevation and is the lowest body of water on the surface of  Earth . For several decades in the mid-20th century the standard value given for the surface level of the lake was some 1,300 feet (400 metres) below  sea level . Beginning in the 1960s, however, Israel and Jordan began diverting much of the Jordan River’s flow and increased the use of the lake’s water itself for commercial purposes. The result of those activities was a precipitous drop in the Dead Sea’s water level. By the mid-2010s measurement of the lake level was more than 100 feet (some 30 metres) below the mid-20th-century figure—i.e., about 1,410 feet (430 metres) below sea level—but the lake continued to drop by about 3 feet (1 metre) annually. YouTube Link  -  https://www.youtube.com/watch?v=c3k1o2dqLD8 Credits -  https://www.britannica.com/place/Dead-Sea Picture Credits - To the rightful owner

Everyone who has been to the beach knows that seawater is salty. Everyone also knows that fresh water in rain, rivers, and even ice is not salty. Why are some of Earth’s waters salty and others not? There are two clues that give us the answer. First, “fresh” water is not entirely free of dissolved salt. Even rainwater has traces of substances dissolved in it that were picked up during passage through the atmosphere. Much of this material that “washes out” of the atmosphere today is pollution, but there are also natural substances present. As rainwater passes through soil and percolates through rocks, it dissolves some of the minerals, a process called  weathering .  This is the water we drink, and of course, we cannot taste the salt because its concentration is too low. Eventually, this water with its small load of dissolved minerals or salts reaches a stream and flows into lakes and the ocean. The annual addition of dissolved salts by rivers is only a tiny fraction of...

Ice floats because it is about 9% less dense than liquid water. In other words, ice takes up about 9% more space than water, so a liter of ice weighs less than a liter water. The heavier water displaces the lighter ice, so ice floats to the top. One consequence of this is that lakes and rivers freeze from top to bottom, allowing fish to survive even when the surface of a lake has frozen over. If ice sank, the water would be displaced to the top and exposed to the colder temperature, forcing rivers and lakes to fill with ice and freeze solid. A substance floats if it is less dense, or has less mass per unit volume, than other components in a mixture. For example, if you toss a handful of rocks into a bucket of water, the rocks, which are dense compared to the water, will sink. The water, which is less dense than the rocks, will float. Basically, the rocks push the water out of the way or displace it. For an object to be able to float, it has to displace a weight of fl...

All boats can float, but floating is more complex and confusing than it sounds and it's best discussed through a scientific concept called  buoyancy , which is the force that causes floating. Any object will either float or sink in water depending on its  density  (how much a certain volume of it weighs). If it's more dense than water, it will usually sink; if it's less dense, it will float. It doesn't matter how big or small the object is: a  gold  ring will sink in water, while a piece of plastic as big as a football field will float. The basic rule is that an object will sink if it weighs more than exactly the same volume of water. But that doesn't really explain why an aircraft carrier (made from dense metal) can float, so let's explore a bit further. Buoyancy is easiest to understand thinking about a  submarine . It has diving planes (fins mounted on the side) and ballast tanks that it can fill with water or air to make it rise or fall as it needs t...

Sometimes when the moon orbits Earth, it moves between the sun and Earth. When this happens, the moon blocks the light of the sun from reaching Earth. This causes an eclipse of the sun ,  or solar eclipse. During a solar eclipse, the moon casts a shadow onto Earth. There are three types of solar eclipses. The first is a total solar eclipse. A total solar eclipse is only visible from a small area on Earth. The people who see the total eclipse are in the center of the moon’s shadow when it hits Earth. The sky becomes very dark, as if it were night. For a total eclipse to take place, the sun, moon and Earth must be in a direct line. The second type of solar eclipse is a partial solar eclipse. This happens when the sun, moon and Earth are not exactly lined up. The sun appears to have a dark shadow on only a small part of its surface. The third type is an annular (ANN you ler) solar eclipse. An annular eclipse happens when the moon is farthest from Earth. Because the moon is ...

It wasn’t until 1979 that Richard Nolle first defined the supermoon, which is now a widely-used term. The astrologer explained that the phenomenon is “a new or full moon which occurs with the moon at or near (within 90% of) its closest approach to Earth in a given orbit.” Based on Nolle’s theory, the moon would have to be 226,000 miles away from the Earth to be considered ‘super’. Because of its relatively close proximity to the Earth, the celestial body’s surface appears a lot bigger when a supermoon occurs. The scientific event is fairly uncommon, as it can occur around every 14 full moons. The last one occurred on November 14 2016, when the moon appeared upto 14% bigger and 30% brighter than normal. It was the closest Supermoon to the Earth all year, reaching an orbit of 221,500 miles away. While the space event provides spectacular views, it is made even more incredible when it coincides with a lunar eclipse. The last time this happened was on September 27 t...

A "Blue Moon" is a fairly infrequent phenomenon involving the appearance of an additional full moon within a given period. But which period — there are two definitions of the term, and one was borne out of a misunderstanding of the other. The older meaning defines a Blue Moon as the third full moon in a season that has four full moons. Called a seasonal Blue Moon, this occurs about every 2.7 years. Why the third moon? Seasons normally have three full moons, and some of them, for traditional and religious reasons, must occur at specific times of the year. The other meaning is that a Blue Moon is the second full moon within a single calendar month. This definition — a monthly Blue Moon — has gained popularity in recent years because of a misinterpretation of an almanac's original definition. Blue Moons are not typically blue in color — that happens only, well,  once in a Blue Moon , but there is the possibility for a hint of blue in any full moon. YouTube Li...

A  lunar eclipse  occurs when the  Moon  passes directly behind the  Earth  into its  umbra  (shadow).  A lunar eclipse can occur only the night of a  full moon .  A total lunar eclipse has the direct sunlight completely blocked by the earth's shadow. The only light seen is refracted through the earth's shadow. This light looks red for the same reason that the sunset looks red, due to  rayleigh scattering  of the more blue light.  Because of its reddish color, a total lunar eclipse is sometimes called a B lood Moon . Unlike a  solar eclipse , which can be viewed only from a certain relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of the Earth. A lunar eclipse lasts for a few hours, whereas a total solar eclipse lasts for only a few minutes at any given place, due to the smaller size of the Moon's shadow. Also unlike solar eclipses, lunar eclipses are safe to...

A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying. Because no light can get out, people can't see black holes. They are invisible. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars. A black hole can not be seen because strong gravity pulls all of the light into the middle of the black hole. But scientists can see how the strong gravity affects the stars and gas around the black hole. Scientists can study stars to find out if they are flying around, or orbiting, a black hole. When a black hole and a star are close together, high-energy light is made. This kind of light can not be seen with human eyes. Scientists use satellites and telescopes in space to see the high-energy light. Scientists think the sm...

Real images are those where light actually converges, whereas virtual images are locations from where light appears to have converged. Real images only occur when for objects which are placed outside the focal length of a convex lens. A real image is illustrated below.  Ray tracing  gives the position of the images by drawing one ray perpendicular to the lens that passes through the focal point, and a second ray that passes through the center of the lens (this ray is not bent by the lens). The intersection of the two rays gives the position of the image. Note that the real image is inverted and larger than the object. The position of the image can be found through the equation : Here, the distances are those of the object and image respectively as measured from the lens. The focal length  f  is positive for a convex lens. A positive image distance corresponds to a real image, just as it did for the case of the mirrors. However, for a lens, a positive imag...

Total internal reflection ,  in  physics , complete  reflection  of a ray of  light  within a medium such as water or glass from the surrounding surfaces back into the medium. The phenomenon occurs if the angle of incidence is greater than a certain limiting angle, called the  critical angle . In general, total internal reflection takes place at the boundary between two transparent media when a ray of light in a medium of higher  index of refraction  approaches the other medium at an angle of incidence greater than the critical angle. For a water-air surface the critical angle is 48.5°. Because indices of  refraction  depend on wavelength, the critical angle (and hence the angle of total internal reflection) will vary slightly with wavelength and, therefore, with colour. At all angles less than the critical angle, both refraction and reflection occur in varying proportions. YouTube Link -  https://www.youtube....

The law of reflection governs the reflection of light-rays off smooth conducting surfaces, such as polished metal or metal-coated glass mirrors. Consider a light-ray incident on a plane mirror, as shown . The law of reflection states that the incident ray, the reflected ray, and the normal to the surface of the mirror all lie in the  same plane . Furthermore, the angle of reflection   is  equal  to the angle of incidence  . Both angles are measured with respect to the normal to the mirror. The law of reflection also holds for non-plane mirrors, provided that the normal at any point on the mirror is understood to be the outward pointing normal to the local tangent plane of the mirror at that point. For rough surfaces, the law of reflection remains valid. It predicts that rays incident at slightly different points on the surface are reflected in completely different directions, because the normal to a rough surface varies in direc...

Reflection is a very common word and is related to the fields of physics and mathematics. The basic meaning of a reflection is  ‘Something Returned in Response’ . Even in our conversation we use this term at times, to mean a some one’s reaction. In optics, it relates to an image of an object. Light rays are basically wave motions and they are capable of being reflected by an interface in between two mediums. Such interfaces are called  Light Reflectors .  The most common Light reflector is the one we use many times a day, which is nothing but a plane mirror. But it is not only a plane mirror reflects light. Even a curved mirror does that though the nature of reflection of light by curved mirrors is different. YouTube Link -  https://www.youtube.com/watch?v=9PRRUgoTSro Credits -  http://physics.tutorvista.com/light/reflection.html

Raman effect -   change in the wavelength of  light  that occurs when a light beam is deflected by  molecules . When a beam of light  traverses  a dust-free, transparent sample of a  chemical compound , a small fraction of the light emerges in directions other than that of the incident (incoming) beam. Most of this scattered light is of unchanged wavelength. A small part, however, has wavelengths different from that of the incident light; its presence is a result of the Raman effect. The phenomenon is named for Indian physicist  Sir Chandrasekhara Venkata Raman , who first published observations of the effect in 1928.  YouTube Link -  https://www.youtube.com/watch?v=yQ1MctWU9Mg Credits -  https://www.britannica.com/science/Raman-effect

The universe is all the matter, energy, and space that exist. We can observe only a part of it - the observable universe. The entire, universe, including the part we cannot see, may be infinite. Galaxies form and evolve within an expanding and cooling universe. Because light takes billions of years to cross the cosmos, we see distant galaxies as they were at earlier times. Astronomers not only theorize about cosmic evolution - they can actually observe its various stages. The Big Bang is the scientific description of the origin of the cosmos. It describes the beginning of the universe as an explosion of space, which has expanded and cooled ever since. If we rewind the expansion of space and go backward in time, galaxies crowd closer and closer together in the past. Ultimately, all matter and energy is compressed at extremely high density and temperature. The observable universe fits within a volume smaller than a grain of sand. That superdense medium exploded in the Big Bang, l...

The periodic table is the most important chemistry reference there is .  It arranges all the known elements in an informative array. Elements are arranged left to right and top to bottom in order of increasing atomic number. Order generally coincides with increasing atomic mass. The different rows of elements are called periods. The period number of an element signifies the highest energy level an electron in that element occupies (in the unexcited state). The number of electrons in a period increases as one traverses down the periodic table; therefore, as the energy level of the atom increases, the number of energy sub-levels per energy level increases. Using the data in the table scientists, students, and others that are familiar with the periodic table can extract information concerning individual elements. For instance, a scientist can use carbon's atomic mass to determine how many carbon atoms there are in a 1 kilogram block of carbon. YouTu...

Rust  is an  iron oxide , usually red  oxide  formed by the  redox  reaction of  iron  and  oxygen  in the presence of  water  or air moisture.  Rust consists of hydrated  iron(III) oxides  Fe 2 O 3 · n H 2 O and  iron(III) oxide-hydroxide  (FeO(OH), Fe(OH) 3 ) Given sufficient time, oxygen, and water, any iron mass will eventually convert entirely to rust and disintegrate. Surface rust is flaky and  friable , and it provides no protection to the underlying iron, unlike the formation of  patina  on copper surfaces. Rusting is the common term for  corrosion  of iron and its alloys, such as  steel . Many other  metals  undergo similar corrosion, but the resulting oxides are not commonly called rust YouTube Link -  https://www.youtube.com/watch?v=EXaa5Ex5y1g Credits -  https://en.wikipedia.org/wiki/Rust

Archimedes’ principle states that  any body completely or partially submerged in a  fluid  ( gas  or  liquid ) at rest is acted upon by an upward, or buoyant,  force  the magnitude of which is equal to the weight of the fluid displaced by the body. The volume of displaced fluid is equivalent to the volume of an object fully immersed in a fluid or to that fraction of the volume below the surface for an object partially submerged in a liquid. The weight of the displaced portion of the fluid is equivalent to the magnitude of the buoyant force. The buoyant force on a body floating in a liquid or gas is also equivalent in magnitude to the weight of the floating object and is opposite in direction; the object neither rises nor sinks.  EXAMPLE  -  a ship that is launched sinks into the ocean until the weight of the water it displaces is just equal to its own weight. As the ship is loaded, it sinks deeper, displacing more water, and so t...