The Milky Way

The Milky Way is a large band of stars, dust and gas that make up our galaxy. It contains billions of stars. Our sun and the solar system is only one of them. The Milky Way is only one of billions of galaxies that make up our universe. It has a diameter of about 100,000 light years and is as old as the universe itself. The name probably refers to how we see our galaxy - a white blurry band that looks like spilled milk.

The Milky Way has the shape of a thin disk with six spiral arms coming out of a bulge in the center . This bulge consists of a cluster of large stars, gas and dust as well as a strong magnetic field. The whole galaxy rotates around this inner bar of stars. New stars are constantly formed around the spiral arms. Most of the stars in our galaxy are red dwarfs, cold stars that are much smaller than our sun.

 The galaxy gets flatter towards the edges. The center of the Milky Way consists of a black hole; an invisible object that has such a strong gravitational pull that not even light cannot escape. The galaxy is surrounded by a gigantic halo made up of old stars and gas that stretches hundreds of thousands of light years into the universe.

Our solar system is located on the inner edge of one of the spiral arms, about 30,000 light years from the centre. It completes one orbit around the centre about every 240 million years.

 Astronomer Edwin Hubble was the first to find out that the Milky Way is only one of many galaxies in our universe. The nearest is Andromeda, which is often referred to as our sister galaxy. It is estimated that in about 4 billion years the Milky Way and Andromeda will collide.

Words

• astronomer = a scientist who studies the sky and the stars
• bar = band
• billion = a thousand million
• blurry = unclear
• bulge = a thick curved mass
• cluster = very many
• collide = crash
• constantly = always
• contain = is made up of
• diameter = the distance from one end of a circle to the other
• disk = round flat shape
• dust = very small particles of dirt
• dwarf = a creature that looks like a very small man
• edge = border, rim
• escape = get away
• estimate = guess, think
• gravitational pull = the force that pulls something towards it
• halo = circle of light
• invisible = something that cannot be seen
• light years = the distance that light travels in one year ( about 6 000 000 000 000 miles)
• located = exists, can be found
• orbit = to move around an object in a circle
• refer = is about
• rotate = to go around
• spill = when a liquid flows over the edge of a container by accident
• spiral = to move in a curve that gets nearer to or farther from the center as it goes around
• stretch = reach from one place to another
• surrounded = around it

Lightning

Lightning 

 Lightning is a form of electricity that is set free during a storm. Energy is suddenly released in a cloud when charges are built up. Although lightning is most common in tropical and subtropical regions, it can happen wherever hot air mixes with cold air. Thunderstorms produce about 8 million lightning bolts a day.

For a long time lightning was a big mystery. Ancient people thought that god was punishing people by sending a bolt of lightning down to Earth.

 How lightning forms

Water droplets and ice crystals in a cloud have electric charges, positive and negative ones. Lightning happens when too many negative charges build up in a cloud and positive charges develop on the ground.

The particles want to meet and race towards each other. A flash of lightning is a sign of this meeting. Such a charge of light can be very hot, up to 20,000 degrees Celsius. It can be up to 5 km long. Large clouds produce more electric charges and eventually a very strong electrical current.

Lightning can also occur between two clouds or within a single cloud. In rare cases negative charges can form on the ground and lighting moves upwards, as is the case when a rocket starts.
Lightning strikes very quickly, several times within a second, but single bolts of lightning are impossible to see with a naked eye. A series of such bolts appear as a single flash.

Thunder accompanies lightning. It forms when electricity travels quickly through the air and starts vibrating. The hot air surrounding a bolt of lightning causes the air to expand, causing noise.

 Effects

Lightning can do damage to buildings, cars or other objects when it hits.  It can also kill or injure human beings. During a thunderstorm people should stay away from doors, windows and electrical devices.  You should also stay away from phones and wires because lightning can travel through them. When you’re in the open do not try to protect yourself by hiding under a tree.

You can protect your house or other buildings surrounding your home by installing a lightning rod on the roof. It attracts the lighting that would otherwise hit the building and leads it to the surface.

Lightning can also have positive effects. It produces nitrates and other compounds when it is created in the air. These nutrients fall down to Earth and enrich the soil for good farming.

Words

• accompany = go with; to happen together with
• although = while
• ancient =  old
• attract = pull towards itself
• bolt =lightning that appears as a white line in the sky
• charge = here: small amount of electricity 
• common = often seen
• damage = destroy
• develop = grow
• device = object, tool, machine
• droplet = small drop
• electrical current = flow of electricity
• enrich = to make better
• eventually = in the end
• expand = become larger
• flash = white burst
• human being = person
• injure = hurt
• install = put in, set up
• lightning rod = metal wire that is fixed to the top or side of a building  and is used to protect the it from lightning
• nitrate = substance that has nitrogen and oxygen in it and is used to make plants grow better
• nutrient = chemical or food that gives plants what they need to grow
• occur = happen
• otherwise  = or else
• punish = to make someone suffer because they have done something wrong
• race = move quickly
• rare = not very often
• release = set free
• series = one after the other
• several = many
• sign = signal
• soil = top layer of earth on which plants grow
• suddenly = unexpectedly, all of a sudden
• surface = the top part of something
• surrounding = around
• towards = in the direction of
• wire = thin cable of metal that can carry electricity

Astronomy

 

Astronomy

Astronomy is about studying space, the universe, stars and the planets in our solar system. Astronomers are scientists who try to find answers to questions relating to our universe. They observe planets, faraway stars and galaxies as well as certain events that occur in space. They examine the structure of the universe and try to find out how it all began.

Ancient Astronomy

Astronomy has been around for thousands of years.  In ancient times, people observed the sun and the stars on a daily basis. They planted crops and held certain events relating to the movement of objects in the sky.

Ancient civilizations, like the Greeks and Romans, however did not have the instruments that later generations had. They had to observe the skies and stars with their naked eye.  It helped them navigate the seas and guide them to other places.

They saw that stars were arranged in patterns that looked like humans or animals.
In ancient times, people thought that the Earth was the centre of the universe and that everything revolved around it. Towards the end of the Middle Ages some astronomers were not quite convinced about this  theory. In the early 16th century Nicolaus Copernicus, a Polish astronomer, was the first to show that in fact the sun was the centre of the solar system and planets revolved around it. Almost a century later Italian astronomer Galileo used the first telescope to observe space. His studies supported Copernicus’ theories. German mathematician Johannes Kepler proved that planets travel around the sun in elliptical paths. Isaac Newton used Kepler’s findings to explain how gravity worked.

 Modern astronomy

The discovery of the telescope changed the way scientists could observe space. While ancient people only were able to see objects near Earth, telescopes were able to find Uranus, Neptune and Pluto, the distant planets of our solar system.

Astronomers also found that an asteroid belt moves around the sun between the Earth and Mars. With the help of powerful telescopes, they were able to  map the surface of the moon and other planets in great detail.

Modern astronomy uses powerful telescopes on earth to see objects far away from our solar system. It also relies on images sent to earth from orbiting telescopes, like the Hubble Space Telescope, which has been in operation since 1990.

Unmanned spacecraft that land on the moon and other planets give astronomers large amounts of data and images that they can use for their work. Astronomers also study samples of rocks that spacecraft have brought back to Earth.

Today, astronomers use computers to simulate movements and events that may happen in space. For example, they can predict how close an asteroid can come to earth or when certain comets appear.

Astronomers measure distances in light years – how far light can travel in one year, which is about 6 trillion miles (9.4 trillion km). They have found out that our galaxy, the Milky Way, has a diameter of 100,000 light years. The nearest star is Proxima Centauri, about four light years away from Earth.

 

Space Agencies Go For Jupiter and Saturn

 

NASA and the European Space Agency have decided to go ahead with an ambitious plan to send a probe to Jupiter and its icy moon Europa. A further project would involve the two agencies to send a spacecraft to Saturn’s moon Titan.

David Southwood, ESA’s Director of Science says that the joint venture is a wonderful new challenge and it will be a milestone of 21 st century space exploration. The Jupiter mission has been chosen to start because it is the more realistic project.

Scientists have been dreaming of visiting Europa for a long time. The icy moon may have underground water and researchers want to find out if such a satellite may be fit for life. It is surely one of the places in the solar system where life might have evolved some time ago.

The project calls for NASA to send an orbiter to Europa and ESA to send one to Jupiter’s moon Ganymede. Both spacecraft would be launched in 2020, but from two separate launch sites. They would reach Jupiter by 2026 and examine the moons for the following three years. Although the two spacecraft would observe Europa from different positions only the NASA probe would spend time in Europa’s orbit.

The moon is said to have a strong radiation field and orbiting it would only be possible for a few months. NASA plans to use special equipment to protect its probe. The two probes would end their mission by crashing into the moons they are orbiting around.

British scientists and engineers will play key roles in the joint mission. A consortium is planning to prepare probes with instruments that would be dropped onto Europa’s surface. Thus, it could determine temperatures under the surface or locate magnetic and radiation fields.

 

Galileo Galilei

Galileo is often called the founder of modern science. He made many discoveries in astronomy and physics and he built telescopes to study space.

Galileo Galilei was born in Pisa, Italy in 1564. His father sent him to the university to study medicine, but young Galileo was more interested in science and mathematics.

Galileo made one of his greatest discoveries as he sat in a cathedral of Pisa. As he watched a chandelier swing back and forth he noticed that longer and shorter swings took the same time. This discovery became known as the law of the pendulum. These and other important discoveries made him so well-known that Galileo became a professor at the University of Pisa.

 Galileo often questioned scientific facts of his age. For a long time people thought that heavier objects fall to Earth faster than lighter ones. By dropping objects of the same size but different weights from the Leaning Tower of Pisa Galileo showed that this wasn’t true.

 In 1609 Galileo constructed his first telescope. He used it to observe the stars and the planets. He saw things that nobody had ever seen before. Galileo discovered that the moon’s surface was not smooth and flat, like everyone thought, but had a rough surface and was full of craters.

In January 1610 Galileo discovered 4 moons revolving around the Jupiter. They were named after him, the Galilean moons. These observations proved that not the Earth was the centre of the solar system, but the sun. It was a discovery that Copernicus had made 60 years earlier.

The Roman Catholic Church did not always like what Galileo taught. It still believed that the Earth was the centre of the universe and everything revolved around it. The church ordered him not to teach such ideas any more.

In 1633 Galileo was brought before the Inquisition, the Church’s court. It sentenced him to life in prison because of his teachings. Galileo was put under house arrest because he was old and not so healthy any more. He spent the last years of his life in Florence, where he continued to work on his theories and even published a final book. He became blind and died in 1642.

In 1992 Pope John Paul II published a document that said the Church made a mistake by condemning Galileo.

Albert Einstein

 Albert Einstein - Life and DiscoveriesAlbert Einstein - Life and Discoverie

Albert Einstein

Albert Einstein was a famous scientist who completely changed the way that people saw our world and the universe. Einstein created many theories which proved that things like gravity , light, energy and matter were connected with each other. At first, very few scientists could understand Einstein’s theories but as time passed other scientists showed that he was correct.

Albert Einstein was born in Ulm, Germany in 1879 and grew up in Munich. He wasn’t a good student at school and only did things he was interested in, like science and mathematics. At a very early age young Albert started wondering about the mysteries of the universe.

After school Einstein went to Switzerland and tried to become a teacher there, but he couldn’t find a job. He went to work at the Swiss patent office in Bern where he studied what other people had invented .

After divorce from his first wife, a classmate of his, Albert went to Berlin where he married his cousin Elsa. He lived in Berlin for a long time and there he developed many of his scientific theories. Einstein became so well known that he was invited to universities around the world to talk about his discoveries . In 1921 he received the Nobel Prize for Physics.

In the meantime things were starting to change in Germany. Einstein was against the Nazis and their ideas of controlling the world and killing Jews. The Nazis, in return, hated him and his theories and they burned most of his books.

Einstein decided to leave Germany and go to the United States. When World War II broke out in 1939 Einstein discovered that German scientists were working on a bomb that could kill thousands of people. He wrote a letter to the American president to warn him and suggested that the Americans start building one too.

In 1941 the American government started the Manhattan Project which led to the construction of the atomic bomb. Two of these bombs were dropped over Hiroshima and Nagasaki to end the war against Japan. Einstein was horrified when he heard the news. He wanted the world to use atomic energy for peaceful purposes .

For the last twenty years of his life, Einstein lived in Princeton where he continued his scientific work. He died on April 18, 1955

One of the most famous equations ever written came from Albert Einstein : E = mc 2 . Energy is mass times the squared speed of light. This equation shows that mass can be turned to energy. Because the speed of light square is such a high number even a small amount of mass can be turned into a lot of energy.

This means, for example, that there is enough energy in a glass of water to give power to a city like London for a whole week. The problem is how to get the energy out of the mass . This equation led to the building of the atomic bomb. The first bomb only had 0.6 grams of mass but scientist turned it into enough energy to destroy a whole city.

 Einstein also thought that space and time were closely related to each other. He thought that there were not three dimensions to objects but four—the fourth one was time. Other scientists, who continued his work, claimed that it is possible to travel into the past and into the future. Black holes might be tunnels that could take you back and forth in time .

According to Einstein all objects followed curved paths and get attracted by the gravity of an object. Time would pass more slowly if you are close to a very large object like a planet. This means that the clock of a plane goes faster than a clock at an airport because the plane is farther away from the earth.

Temperature inversion

 Temperature inversion layers, also called thermal inversions or just inversion layers, are areas where the normal decrease in air temperature with increasing altitude is reversed and the air above the ground is warmer than the air below it. Inversion layers can occur anywhere from close to ground level up to thousands of feet into the atmosphere.

Inversion layers are significant to meteorology because they block atmospheric flow which causes the air over an area experiencing an inversion to become stable. This can then result in various types of weather patterns.

More importantly, though, areas with heavy pollution are prone to unhealthy air and an increase in smog when an inversion is present because they trap pollutants at ground level instead of circulating them away.

Causes

Normally, air temperature decreases at a rate of 3.5°F for every 1,000 feet (or roughly 6.4°C for every kilometer) you climb into the atmosphere. When this normal cycle is present, it is considered an unstable air mass, and air constantly flows between the warm and cool areas. The air is better able to mix and spread around pollutants.

During an inversion episode, temperatures increase with increasing altitude. The warm inversion layer then acts as a cap and stops atmospheric mixing. This is why inversion layers are called stable air masses.

Temperature inversions are a result of other weather conditions in an area. They occur most often when a warm, less dense air mass moves over a dense, cold air mass.

This can happen, for example, when the air near the ground rapidly loses its heat on a clear night. The ground becomes cooled quickly while the air above it retains the heat the ground was holding during the day.

Temperature inversions also occur in some coastal areas because upwelling of cold water can decrease surface air temperature and the cold air mass stays under warmer ones.

Topography can also play a role in creating a temperature inversion since it can sometimes cause cold air to flow from mountain peaks down into valleys. This cold air then pushes under the warmer air rising from the valley, creating the inversion.

In addition, inversions can also form in areas with significant snow cover because the snow at ground level is cold and its white color reflects almost all heat coming in. Thus, the air above the snow is often warmer because it holds the reflected energy.

Consequences

Some of the most significant consequences of temperature inversions are the extreme weather conditions they can sometimes create. One example is freezing rain.

This phenomenon develops with a temperature inversion in a cold area because snow melts as it moves through the warm inversion layer. The precipitation then continues to fall and passes through the cold layer of air near the ground.

When it moves through this final cold air mass it becomes "super-cooled" (cooled below freezing without becoming solid.) The supercooled drops then become ice when they land on items like cars and trees and the result is freezing rain or an ice storm.

Intense thunderstorms and tornadoes are also associated with inversions because of the intense energy that is released after an inversion blocks an area’s normal convection patterns.