KNOWLEDGE IS POWER

The Milky Way – Our Galaxy

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.

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.