The Universe- Characterstics of Universe

 Key Concepts

• Universe

Introduction: 

What is Universe?  

The universe is nothing but everything we can feel, touch, sense, measure, and detect. The universe includes planets, stars, galaxies, living things, dust, clouds, time, and even light. Before the origin of the universe, space, matter and time did not exist. The universe is considered an endless space, and all living things, including human beings, belong to space. 

The scientific study of the universe is called astronomy. The scientist who studies the universe is known as an astronomer. 

Astronomers have made very exciting discoveries such as stars, galaxies, planets, nebulas, etc., by observing the universe. By studying these objects (galaxies, nebula, planets etc.), astronomers were able to learn about the origin of the Earth and the steps involved in the formation of the solar system and other objects present in the universe. 

We know that the universe contains billions of galaxies, and each contains millions of stars. The space between stars and galaxies is mostly empty; even places far away from stars and planets consist of scattered dust particles or a few hydrogen atoms per cubic centimeter. Space is covered with radiations such as light radiation, heat radiation, magnetic fields, and high energy particles such as cosmic rays. 

Characteristics of the Universe 

Cosmology is the study of the origin, characteristics, processes, and evolution of the universe. Astronomers studied and found out that the universe started almost 13.7 billion years ago in one massive explosion called the big bang, and since that time the universe is expanding. The universe is too large, and the objects present in it are far away from each other, so a telescope is used to study far away objects. Nowadays, with scientific development, astronomers also use computers and mathematical models to study the universe. 

Organization of the Universe 

The solar system is the closest part of the universe to Earth. The solar system consists of the sun, Earth, other planets, dwarf planets, asteroids, and comets. It (the solar system) is a part of the galaxy. The galaxy is consists of stars, dust particles, and gas forced together by gravity. The milky way of the galaxy is the galaxy in which the solar system is present. There are billions of galaxies present beyond the milky way galaxy. 

Measurement of distance in the Universe 

We know that the universe is very big and the units of measurement on Earth are very small to show the distance between the various objects present in space. So to measure distance, astronomers usually use astronomical units. The astronomical unit (represented by AU) is defined as the average distance between Earth and the sun, which is approximately 150 million km. The speed of light is also used to measure distance. Light travels at the speed of 300,000 km/s. Light travels 9.46×1012 km in one year. This distance is called a light year. Apart from the sun, the closest star to Earth is 4.22 light-years away. 

Observing Space 

We could see the world around us and make observations because of light. At night, we can see stars and other objects in space because these objects emit light. This visible light is nothing but a small amount of energy that comes from objects. Astronomers are able to learn more about the universe by studying other forms of energy. We know that planets do not emit light, but they reflect light coming from stars. 

Electromagnetic spectrum: 

Visible light is a form of energy and is a part of the electromagnetic spectrum. The electromagnetic spectrum is defined as all the wavelengths of electromagnetic radiation. Examples of electromagnetic radiation are light, radio waves, and x-rays. 

Visible Electromagnetic Radiation: 

We can see only radiation of wavelength present in the visible light range of the spectrum. Electromagnetic radiation that has shorter wavelengths than violet light or longer than red light wavelengths cannot be seen by the human eye. 

Invisible Electromagnetic Radiation: 

In 1800, scientist William Herschel discovered infrared light, which means below the red. The wavelength of infrared radiation is longer than visible light. The ultraviolet electromagnetic radiation means beyond the violet. Gamma rays have the shortest wavelengths. 

Telescopes: 

Our eyes cannot see very small objects that are too far for our eyes to see them. In 1609, Italian scientist Galileo made one device and turned it towards the sky. He could see craters on the moon, and the milky way was made up of stars. Afterwards, Isaac Newton discovered another kind of telescope. 

A telescope is a device that collects electromagnetic radiations coming from the sky and focuses it for good quality observation. 

Types of Telescopes: 

The first telescope that was developed used to collect only visible light. Modern telescopes are able to collect and use invisible infrared radiations. 

Optical Telescopes: 

The telescopes that collect only visible light are called optical telescopes. There are two types of optical telescopes – refracting telescopes and reflecting telescopes. 

Refracting Telescope: 

These telescopes use a set of lenses to collect and focus light from far-away objects. One drawback with a refracting telescope is that its lens focuses on different colors of light at different distances. 

Reflecting Telescopes: 

These telescopes are much larger and gather more light than refractive telescopes. It has a curved mirror to collect light from far-away objects. 

Radio Telescope: 

Some telescopes detect invisible radiations. For example, a radio telescope detects radio waves. There are telescopes to detect gamma rays, x-rays and infrared rays. The drawback with telescopes that detect invisible radiation is that the Earth’s atmosphere acts as a protective cover against many types of electromagnetic radiation. 

Ground-based telescopes cannot give valuable information about the universe. Valuable information comes from spacecraft. Spacecraft contain telescopes and other devices to investigate planets, stars and other faraway objects. 

Space Telescope: 

Hubble space telescope is launched into space to collect electromagnetic radiation from objects present in space. 

The Swift spacecraft identifies x-rays and gamma rays from explosions and collisions of objects such as black holes. 

The Spitzer space telescope finds out infrared radiation. 

The James Webb space telescope is used to find out near-by and mid-range infrared radiation from objects in space. 

Human Space Exploration: 

A robotic is a spacecraft that carries only devices and computers. This spacecraft can travel around space and travel beyond the solar system. Satellites in the orbit give information about weather all over the Earth. This information helps scientists to make correct weather forecasts. 

Summary

• The universe includes planets, stars, galaxies, living things, dust, clouds, time, and even light.
• The scientific study of the universe is called astronomy.
• The scientist who studies the universe is known as an astronomer.
• Cosmology is the study of the origin, characteristics, processes, and evolution of the universe. The galaxy is consists of stars, dust particles, and gas forced together by gravity.
• The milkyway of the galaxy is the galaxy in which the solar system is present.
• The electromagnetic spectrum is defined as all the wavelengths of electromagnetic radiation. Examples of electromagnetic radiation are light, radio, waves, and x-rays.
• A telescope is a device that collects electromagnetic radiations coming from the sky and focuses it for good quality observations.