Basic Astronomy
Synopsis
- Astronomy
- Big Bang Theory
- Electromagnetic Radiation
- Star Formation
- Life Cycle Of A Star
- Source Of Sunlight
- Our Solar System
- Dark Matter - Dark Energy
- Finding Exoplanets
- Golden Record
- Space Telescopes
- Conclusion
- Reference
Astronomy
Astronomy is a vast subject that heavily relies on mathematics and logical reasoning. Concepts in astronomy are established using a diverse set of data, drawing on scientists imagination, scientific methods, evidence, and information. The foundations of ancient astronomy, rooted in mathematics, were laid by Pythagoras, while logical reasoning was proposed by Aristotle.
Astrophysics, a branch of astronomy, consistently grapples with uncertainty, prompting scientists to employ scientific methods to ensure the accuracy of their results. A diverse set of data is collected, utilising available information, while causation and correlation are determined before analysing the theories. Causation implies that one event is the result of another, whereas correlation suggests a connection between two events at a specific point, though changes in one event may not necessarily affect the other.
The scientific method dictates that scientists must formulate a hypothesis (theory) after observing a problem and collecting the necessary data. Scientific evidence can manifest in various forms, such as old data, light, electromagnetic waves, and the laws of nature. Once a hypothesis is developed, scientists proceed to test it through experiments using existing models and laws. If the end results are evidence-based, the hypothesis is validated as a scientific theory through repeated tests. In case of inconsistent results, scientists must retest the hypothesis with necessary adjustments to the inputs.
Science exhibits continuous exponential growth rates, marked by frequent discoveries in classical physics, quantum physics, or statistical mechanics. As one scientist develops a theory, the next generation of scientists often builds upon the foundation of proven theories to explore new ideas. In essence, scientific research relies on both primary and secondary data. Primary data refers to information collected directly by the researcher, while secondary data involves utilising existing data for research purposes.
Big Bang Theory
The Big Bang theory posits that the universe originated and expanded from a singularity, starting as an incredibly hot and dense point. This expansion followed an inflationary model, resembling a fireball in terms of temperature. As the universe expanded and cooled, the Cosmic Microwave Background (CMB) formed, marking the initiation of light radiation. This subtle evidence is crucial for understanding the formation of galaxies and stars.
The CMB radiation, believed to have formed approximately 380,000 years after the Big Bang, serves as primary evidence supporting the idea that the universe began in a hot and dense state 13.8 billion years ago. In terms of elemental composition, hydrogen and helium were forged during the initial stages of the Big Bang, while other elements originated through processes like the formation of massive stars, low-mass stars, and supernovae. Out of the 118 known elements, 92 are natural and were created through the effects of supernova explosions, while 26 elements are man-made.
Electromagnetic Radiation
Electromagnetic radiation is organized by wavelengths into categories, including radio waves, microwaves, ultraviolet waves, visible light, infrared rays, X-rays, and gamma rays. Among these, only visible light is perceptible to the human eye. Fortunately, Earth's atmosphere shields us from exposure to higher radiation waves, which can be harmful to human life. To study these higher energy radiations, space organizations develop large telescopes and deploy them in space, allowing for detailed exploration beyond the constraints of Earth's atmosphere.
Star Formation
A large diffuse cloud of gas transforms into a star and surrounding planets when a supernova explosion sends a shockwave through nearby interstellar gas and dust. This process leads to the collapse of clouds due to gravity, forming swirling (rotating) disks known as the solar nebula. Materials undergo repeated cycles of infall and outfall until they settle into the central region of the cluster. In this central region, gravity at the center pulls the majority of materials, forming stars with mass. The remaining materials outside the disk coalesce to form planets and moons, shaping a solar system. Planets orbit stars according to the relativity theory of space-time curvature, and stars generate light through the fusion process. When stars run out of fuel to sustain fusion, they undergo processes that can result in their transformation into white dwarfs, neutron stars, or black holes, rendering them 'dead' in cosmic terms.
Life Cycle Of A Star
Average stars evolve into white dwarfs, while massive stars can transform into either neutron stars or black holes. Our sun, classified as an average or low-mass star, is expected to become a white dwarf after approximately 5 billion years. When massive stars exhaust their fuel for the fusion process, they expand into red supergiants, eventually leading to a supernova. This explosive event can result in the formation of neutron stars or black holes. Neutron stars are created through neutron degenerate matter, while black holes form when a star surpasses the mass of all other existing stars.
A pulsar is a subset of a neutron star, characterized by its magnetic field rotation. Black holes, though unseen by astronomers, exist due to the event horizon exceeding the speed of light, preventing anything from escaping once it enters. White dwarfs typically have a mass of approximately 1.2 solar masses, neutron stars range from 1.4 to 3 solar masses, and black holes surpass 3 solar masses.
Source Of Sunlight
The source of sunlight is nuclear fusion, a process occurring within the sun's core where hydrogen atoms fuse to form helium atoms, generating high-energy photons known as light. The photons produced from nuclear fusion take approximately 5,000 years to reach the sun's photosphere and about 500 seconds to reach the Earth's atmosphere. The sun's primary radiation is absorbed by the Earth's atmosphere, while the remaining radiation reaches the Earth's surface as visible sunlight.
Plants rely on sunlight for growth, and animals, including humans, depend on plants for both food and the oxygen produced through photosynthesis. Sunlight is also essential for boosting human vitamin D levels. It's crucial to note that without sunlight, Earth would freeze.
Our Solar System
Our solar system comprises planets, moons, asteroids, and comets that orbit around the Sun. Approximately 4.6 billion years ago, a cloud of stardust formed and collapsed, likely triggered by the explosion of a nearby star. This collapse resulted in the formation of a solar nebula, which eventually evolved into a rotating disk of matter. The pressure generated by this matter became so intense that hydrogen atoms began fusing into helium, releasing an immense amount of energy, giving birth to our Sun.
The Sun absorbed over 99% of the material in the disk, while the remaining bits coalesced to form larger spherical objects known as planets. The leftover debris that didn't form planets became rocky asteroids and icy comets. Scientists gain insights into our solar system by studying asteroids and comets.
The Giant Impact Theory suggests that a collision between Earth and a small planet (similar in size to Mars) resulted in the formation of debris in orbit around Earth, eventually coalescing to form our Moon.
Dark Matter - Dark Energy
Two dominant components of the universe are dark matter and dark energy. Astronomers remain uncertain about the physical nature of dark matter and dark energy as they are both invisible. Dark matter constitutes 27%, dark energy covers 68%, and the final component, ordinary matter that we understand, makes up 5%.
Dark matter may interact with gravity but its inability to emit, absorb, or reflect light makes it challenging to detect. Dark energy is believed to be responsible for the observed acceleration in the universe's expansion, according to Hubble observations. A theory proposes that the fundamental forces—gravity, weak force, strong force, and electromagnetic force—might have combined into a superforce at one stage. This superforce is speculated to be a potential explanation for the structure of dark energy, although extraordinary evidence is required to support this concept.
Finding Exoplanets
Directly imaging exoplanets in an image is challenging due to the overwhelming brightness of the stars they orbit. The brightness of these stars obscures the potential for direct imaging as the planets move in their orbits.
The similarity between our solar system and newly discovered distant planetary systems lies in the fact that planets orbit around sun-like stars. However, differences arise in terms of planet mass, and some exoplanets orbit around two or more stars in a binary system.
Two primary indirect methods employed for discovering exoplanets are the Doppler method and the Transit method.
Doppler Method - When a planet orbits a star, causing the star to appear to wobble relative to the center of mass (barycentre), we utilise this wobbling effect to detect the planet's presence using the spectroscopy technique. In simple terms, variations in the color of light emitted by the star help us identify the planet.
Transit Method - As a planet orbits a star, it temporarily blocks the brightness of the star. Through this technique, we can determine the size and density of the planet."
Golden Record
Scientists are actively searching for habitable exoplanets and potential extraterrestrial life. In 1977, NASA launched Voyager into space carrying the golden record—a copper disk containing sounds and images that depict human life on Earth. This idea was proposed by Carl Sagan with the intention of sharing the story of our world with any extraterrestrial beings that may encounter it in the distant future.
Space Telescopes
Light takes time to travel from one place to another. Therefore, when we observe distant objects in the universe, we are essentially looking into the past. The light from these distant objects takes time to traverse the vastness of the universe before reaching us. This is why astronomers often liken large telescopes to time machines, as the light they capture and allow us to observe is essentially old light from the early stages of the universe.
Space telescopes play a crucial role in studying planets, stars, and galaxies in-depth by detecting waves that are not visible from Earth's surface. This is because our atmosphere permits only certain wavelengths of light to pass through while blocking others. Telescopes come in various sizes, and the quality of images is significantly influenced by the diameter of their apertures.
The aperture, referring to the opening in a lens through which light passes to reach the telescope camera, is a key determinant of a telescope's quality. The brightness of the captured image falls on the CCD (Charge-Coupled Device) sensors. The minimum diameter for apertures is 2.8 inches. As the aperture size increases, the diameter also increases, resulting in higher image quality and brightness. Therefore, large telescopes, with their larger diameters, offer the advantage of producing high-quality images of space.
Several telescopes are designed to explore beyond the spectrum of visible light, allowing astronomers to gain insights into the universe. Some examples include,
Chandra Telescope: Designed to detect X-rays.
Spitzer Telescope: Designed to detect Infrared rays.
Compton Gamma Ray Telescope: Designed to detect Gamma rays and X-rays.
Hubble Space Telescope (HST): Designed to detect Visible light, Ultraviolet waves, near Infrared, and deep space.
James Webb Space Telescope (JWST): Designed to look deeper into space to examine the earliest stars and galaxies.
LIGO (Laser Interferometer Gravitational-Wave Observatory) is an observatory designed to detect gravitational waves, which differ from electromagnetic radiation. It is located at ground level on Earth.
Conclusion
If you aspire to become an astronomer, make sure to cultivate commendable confidence in 'THINKING OUTSIDE THE BOX.' This skill is crucial for comprehending objects distant from Earth and generating diverse results that can prove beneficial for humankind.
Reference
NASA Solar System Big Data
Electromagnetic Spectrum
Solar System Video
Sun Video
Universe Origin
Big Bang Theory
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