Week 1 Sci 151 Essay

Light travels at a finite velocity, and so there is always dome time interval between the reflection of light from a physical object or event and the light reaching our eyes. In the case the nearby objects or events, the time interval might be minute. But in the case of a distant star, the time interval may be so considerable that by the time the light reaches our eyes the star may no longer exist.

explain the universe in terms of nine key questions. In pursuit of answers to these questions,

1. Explain what the sun is and how it differs from other stars we see in the sky.

A stars luminosity is measured by the apparent magnitude and absolute magnitude of the star and the amount of the light that is being emitting from it’s surface.

[27] Scientists can determine what a distant star is made of by looking at ____.

Cooler stars emit heat in the infrared area of the electromagnetic spectrum, and thus, they appear to be red. It should also be noted that hot stars radiate energy at the ultraviolet and blue areas, making them appear white or blue. The surface temperature of a celestial object can be determined by using the relationship between the wavelength of the light and the temperature of the blackbody and in the case of an increase in temperature, the tip of the spectrum becomes shorter in

Professor Steve Eales of Cardiff University, UK is lead author on the study. According to him, many people have claimed before that this metamorphosis has occurred. But by using the Herschel and Hubble together for the first time the extent of this transformation has been accurately measured.

∼ 100 times brighter than the stars of its host galaxy. Seyferts and QSOs, however, are not

Secondly, The Hubble's law states that, galaxies are moving away from us at speeds which are directly proportional to their distance. The further away a galaxy is, the faster it is moving away. Edwin Hubble (1889-1953) who is responsible for the creation of the law, discovered the phenomenon in the year of 1923. Edwin Hubble is also known as the father of the expanding universe. This observation made by Edwin Hubble shows us that or suggests that at one point of time, the universe was in fact compressed/compacted. (Bradshaw, John 2009).

The Milky Way contains billions of stars with different ages and sizes. One example of a star which is closest to earth is the Sun. Just like all the other stars the sun is a luminous ball of gas which mostly contains hydrogen and helium and is held together with its own gravity. All the stars produce their own energy by a process called nuclear fusion. Stars life begins in the place what astronomers call the Nebulae. A nebula is enormous cloud consisting of dust and gas; mainly hydrogen and helium. There are three different types of nebulae. The first one is Emission Nebula. Emission Nebulae are usually red and pink in colour because they are filled with hydrogen gas. The Emission Nebula is very hot because of the newborn stars zap there surrounding

The Sun is a star that is located at the centre of our solar system composed primarily of hydrogen and helium with smaller quantities of oxygen, carbon, neon, and iron. The sun keeps our planets in orbit due to its’ large gravitational forces and provides our planet with heat. There are many different ways in which stars can be classified, and The Sun is listed as a G-type Main Sequence star and is also known as a yellow dwarf. It is currently in a phase called the “main sequence” in which 4 hydrogen atoms are fused together to form 1 helium atom as well as energy (4.3x10-12 joules worth). Our sun is approximately half-way through its main sequence phase, and in approximately 5 billion years it will enter it’s post main sequence.

A galaxy, also called a nebula, consists of billions of stars, interstellar gas, dust, and dark matter which are all bound to form a massive cloud in which we live in. Although it cannot be very well explained, dark matter makes up at least 90% of a galaxy’s mass.

in weak gravity field. So far this phenomena has been verified from star to galaxy and from

Astrophysics is the branch of astronomy that employs the principles of physics and chemistry to ascertain the nature of the heavenly bodies, rather than their positions or motions in space. A few of the objects studied are the Sun, other stars, galaxies, extrasolar planets, the interstellar medium and the cosmic microwave background. The study of our very own Sun has a special place in observational astrophysics. Due to the tremendous distance of all other stars, the Sun can be observed in a kind of detail unparalleled by any other star. Our understanding of our own Sun serves as a guide to our understanding of other stars. Their emissions are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.

Big Bang Theory – presupposes that the vast universe grew out of something where all matter and energy were compressed to infinite density and heated to trillions of degrees (a beginning which was an immensely small particle of high-density state. The four basic forces of nature – gravity, electromagnetism, strong and weak atomic forces – were unified in that tiny particle. This particle exploded into a great fire ball releasing the basic forces. Rapid expansion