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Semester 1: Foundation Course EARTH AND ITS SYSTEMS
The Universe and its Origin- Theories of Evolution Nebula, Kant, and Big Bang Theory
The Universe and its Origin: Theories of Evolution Nebula, Kant, and Big Bang Theory
Introduction to the Universe
The universe encompasses all of space, time, matter, and energy. Understanding its origin is a fundamental question in various fields of science.
Nebula Theory
Nebulae are vast clouds of gas and dust in space. They are crucial in star formation, acting as the birthplaces of stars. The nebular hypothesis explains the formation of the solar system from a rotating disk of gas and dust.
Immanuel Kant's Contributions
Kant proposed a model where the universe evolved from chaotic conditions. His work laid the groundwork for modern cosmology by suggesting that the universe was not static and that it changes over time.
Big Bang Theory
The Big Bang Theory is the leading explanation for the origin of the universe. It posits that the universe began as a singularity approximately 13.8 billion years ago and has been expanding ever since.
Comparative Analysis of Theories
While the nebula theory focuses on star formation, Kant's model emphasizes evolution over time. The Big Bang theory offers a comprehensive explanation for the universe's origin and promotes the idea of an expanding universe.
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Earth and Universe - Solar System- Galaxy Milky way Cosmobody Black hole Meteorites
Earth and Universe
Solar System
The solar system consists of the Sun and the celestial bodies that are bound to it by gravity. This includes eight planets, their moons, dwarf planets, asteroids, comets, and meteoroids. The inner planets, Mercury, Venus, Earth, and Mars, are rocky, while the outer planets, Jupiter, Saturn, Uranus, and Neptune, are gas giants.
Galaxy Milky Way
The Milky Way is the galaxy that contains our solar system. It is a barred spiral galaxy, featuring a central bar-shaped structure made of stars. The Milky Way is estimated to have 100 to 400 billion stars and spans about 100,000 light-years in diameter. It also contains vast amounts of gas and dust, as well as dark matter.
Cosmobody
Cosmobodies refer to the vast and diverse range of objects and phenomena found in the universe. This includes planets, stars, galaxies, nebulae, and other cosmic structures. Each cosmobody has unique characteristics, compositions, and behaviors, contributing to the overall complexity of the universe.
Black Hole
A black hole is a region in space where the gravitational pull is so strong that nothing, not even light, can escape from it. They are formed when massive stars collapse under their own gravity at the end of their life cycle. The boundary around a black hole is called the event horizon, beyond which any information is lost.
Meteorites
Meteorites are solid fragments from meteoroids that survive their passage through the Earth's atmosphere and land on the surface. They can vary in size and composition, providing valuable information about the early solar system and the materials that formed the planets. They are classified into three main types: stony, iron, and stony-iron.
Earths Internal Structure Earths Crust, Mantle, and Core Discontinuity
Earth's Internal Structure
Introduction to Earth's Internal Structure
The Earth is composed of several distinct layers, each with unique properties and characteristics. These layers are the crust, mantle, and core.
Earth's Crust
The outermost layer of the Earth, the crust is relatively thin and is composed of solid rock. It can be divided into continental and oceanic crust, with varying thickness and composition. The Earth's crust is crucial for terrestrial life and supports geological processes.
Earth's Mantle
Beneath the crust lies the mantle, which is much thicker and made of semi-solid rock that flows slowly over time. The mantle plays an essential role in tectonic activity and convection currents that drive plate movement.
Earth's Core
The core is the innermost layer of the Earth, consisting of a solid inner core and a liquid outer core. The core is primarily composed of iron and nickel and is responsible for generating the Earth's magnetic field.
Discontinuities Between Layers
Discontinuities are boundaries separating the Earth's layers, including the Mohorovičić discontinuity (Moho) between the crust and mantle, and the Lehmann discontinuity between the outer and inner core. These layers exhibit different physical and chemical properties, affecting seismic wave propagation.
Earth and its Size Earth Rotation and Revolution Inclination Causes Seasons Day and Night Summer and Winter Solstice Eclipses
Earth and its Size, Rotation and Revolution, Inclination, Causes of Seasons, Day and Night, Summer and Winter Solstice, Eclipses
Earth's Size
Earth is the third planet from the Sun and is approximately 12,742 kilometers in diameter. It has a total surface area of about 510 million square kilometers, consisting of 71% water and 29% land. Its equatorial circumference is about 40,075 kilometers. Earth's mass is approximately 5.97 x 10^24 kilograms.
Earth's Rotation
Earth rotates on its axis from west to east, completing one full rotation approximately every 24 hours. This rotation causes the cycle of day and night. The speed of rotation varies, being fastest at the equator at about 1,670 kilometers per hour.
Earth's Revolution
Earth revolves around the Sun in an elliptical orbit, completing one revolution approximately every 365.25 days. This period defines a year. The Earth's average distance from the Sun is about 149.6 million kilometers.
Inclination of the Earth's Axis
Earth's axis is tilted at an angle of about 23.5 degrees relative to its orbit around the Sun. This tilt is responsible for the changing seasons as it affects the angle and intensity of sunlight received by different parts of the Earth throughout the year.
Causes of Seasons
Seasons are caused by the tilt of the Earth's axis and its position in relation to the Sun. During summer in one hemisphere, that hemisphere is tilted towards the Sun, resulting in longer days and higher temperatures. Conversely, during winter, the hemisphere is tilted away, resulting in shorter days and cooler temperatures.
Day and Night
Day and night occur due to Earth's rotation. As the Earth rotates, different regions receive sunlight while others are in shadow. The rotation creates a cycle of light and dark that lasts approximately 24 hours.
Summer and Winter Solstice
The summer solstice occurs around June 21 when the North Pole is tilted closest to the Sun, marking the longest day of the year in the Northern Hemisphere. The winter solstice occurs around December 21 when the North Pole is tilted farthest from the Sun, marking the shortest day of the year.
Eclipses
Eclipses occur when one celestial body moves into the shadow of another body. A solar eclipse happens when the Moon passes between Earth and the Sun, blocking the Sun's light. A lunar eclipse occurs when Earth passes between the Sun and the Moon, casting a shadow on the Moon. Eclipses can only occur during specific alignment of the three bodies.
Latitudes and Longitudes Greenwich Meridian Indian Standard Time Time Calculation
Latitudes and Longitudes, Greenwich Meridian, Indian Standard Time, Time Calculation
Introduction to Latitudes and Longitudes
Latitudes are the angular distance of a point north or south of the equator, measured in degrees. The equator is defined as 0 degrees latitude, while the poles are at 90 degrees North and South. Longitudes are the angular distance of a point east or west of the Prime Meridian, measured in degrees. The Prime Meridian, located at Greenwich, England, is defined as 0 degrees longitude. Together, latitudes and longitudes form a coordinate system that helps in identifying any location on Earth.
Greenwich Meridian
The Greenwich Meridian, also known as the Prime Meridian, is the line of 0 degrees longitude. It is used as the starting point for measuring time zones around the world. The concept of Greenwich Mean Time (GMT) is derived from this meridian, serving as a standard for timekeeping. GMT is the mean solar time at the Royal Observatory in Greenwich.
Indian Standard Time (IST)
Indian Standard Time is the time observed throughout India and Sri Lanka, which is 5 hours and 30 minutes ahead of Greenwich Mean Time (GMT+5:30). IST does not observe Daylight Saving Time. It is determined by the meridian of 82.5 degrees East, which is approximately located at Allahabad, India. This standard time ensures that the entire country operates on the same time.
Time Calculation
Time calculation using latitudes and longitudes involves understanding how time zones are established based on the Earth's rotation. The Earth rotates 360 degrees in approximately 24 hours, leading to a time change of about 15 degrees longitude per hour. To calculate the local time at a specific longitude, one must consider the difference in degrees from the Greenwich Meridian and adjust accordingly. For example, for every 15 degrees east of Greenwich, local time is ahead by one hour, whereas for every 15 degrees west, it is behind by one hour.
