Stars And Solar System
Observing the night sky is a fascinating experience for everyone. You might have watched the clear blue sky some times and also have observed sunrise and sunset several times. What have you observed in the sky? What do you know about celestial objects and their movement? Elderly people seem to know a lot of things. Some of
them can tell the time of the day simply by looking at the shadows of some objects. How do they make such guesses?
Read the following questions and check
1.what you know about the sky and our earth.
2.What are the celestial objects that we can see in the sky?
3.Are the stars moving?
4.Do you see the same stars at night and early in the morning?
5.Do you see the same stars during summer and winter nights?
6.What is the shape of the moon? Why does it change? Why doesn’t the sun change its shape daily like the moon?
7. Where exactly is the sun situated in the sky at noon?
8. Why does the shadow of a tree change from morning to evening?
It is definitely interesting to know answers to the above questions, but it will be more interesting to understand how our ancestors came to an understanding about all these in the olden days and what they observed and how they observed the sky and celestial bodies without using instruments like telescopes. One thing we have to remember that people made these observations from the earth and not from any other point in the sky.
MOON:
The Moon is Earth's only natural satellite, and its formation is thought to be the result of a giant impact hypothesis. Here is a summary of the leading theory on how the Moon formed.
Giant Impact Hypothesis:
The most widely accepted theory is the Giant Impact Hypothesis, which suggests that a Mars-sized body, often referred to as "Theia," collided with the early Earth about 4.5 billion years ago.
The impact was so powerful that it caused a significant amount of material from both Theia and the early Earth to be ejected into space.
Formation of a Disk:
The debris ejected into space began to orbit around the Earth due to gravitational forces, forming a disk of molten rock and debris.
Moon's Accretion:
Over time, the material in the disk began to accrete (come together) to form the Moon. The process of accretion involved the gradual sticking together of smaller particles to form larger bodies.
Moon's Differentiation:
As the Moon continued to accrete, it underwent a process of differentiation. This means that heavier materials sank toward the center, forming the Moon's metallic core, while lighter materials rose to the surface.
Solidification:
The molten rock and debris in the disk eventually cooled and solidified, leading to the formation of the Moon as we know it today.
The Giant Impact Hypothesis is supported by various lines of evidence, including the Moon's composition, isotopic similarities between the Earth and the Moon, and computer models simulating such impacts.
It's important to note that while the Giant Impact Hypothesis is the leading theory, the details of the Moon's formation are still the subject of ongoing research and discussion within the scientific community. Scientists continue to refine and expand our understanding of the Moon's origin through new observations, analyses, and simulations.
THE SOLAR SYSTEM:
The solar system is a vast and complex system that consists of a central star, the Sun, and the celestial bodies, such as planets, moons, asteroids, comets, and other objects, that are bound to it by gravity. Here are some key components of the solar system:
The Sun:
The Sun is a G-type main-sequence star, and it makes up about 99.86% of the solar system's total mass. It is composed mostly of hydrogen and helium and is the primary source of light and energy for the entire solar system.
Inner Planets (Terrestrial Planets):
These are the rocky planets located closer to the Sun. They include Mercury, Venus, Earth, and Mars. These planets are characterized by solid surfaces and are relatively smaller in size compared to the outer planets.
Outer Planets (Gas Giants):
The outer planets are Jupiter, Saturn, Uranus, and Neptune. These planets are much larger than the inner planets and are composed mainly of gases, such as hydrogen and helium. They are also known for their impressive ring systems.
Dwarf Planets:
Pluto was formerly considered the ninth planet, but in 2006, the International Astronomical Union (IAU) reclassified it as a dwarf planet. Other dwarf planets in the solar system include Eris, Haumea, Makemake, and Ceres.
Moons (Natural Satellites):
Many of the planets in the solar system have moons orbiting around them. Earth's Moon is an example, and Jupiter and Saturn have particularly large moon systems.
Asteroid Belt:
Located between the orbits of Mars and Jupiter, the asteroid belt is a region where a large number of small rocky bodies, known as asteroids, orbit the Sun.
Kuiper Belt:
Beyond the orbit of Neptune lies the Kuiper Belt, which is a region containing a vast number of small, icy bodies, including dwarf planets such as Pluto.
Oort Cloud:
The Oort Cloud is a hypothetical region located far beyond the orbit of Pluto, believed to contain a reservoir of icy objects and comets.
Comets:
Comets are small, icy bodies that orbit the Sun in highly elliptical paths. When a comet approaches the Sun, it heats up, and its ices vaporize, creating a bright coma and a tail.
The solar system formed approximately 4.6 billion years ago from a giant molecular cloud of gas and dust. The formation process led to the development of the Sun and the various objects that make up the solar system..
Solar Eclipse:
A solar eclipse occurs when the shadow of the moon falls on the earth. It occurs only on new moon day.
Types of solar eclipse:
1.Total Solar eclipse: It occurs when the moon completely covers the Sun, as seen from earth.
2. Partial Solar eclipse: It can be observed when only the partially shaded outer region of the shadow cast by moon (Lunar penumbra) touches the earth.
3. Annular eclipse: It occurs when the moon appears smaller than the sun as it passes centrally across the solar disk and a bright ring or annulus of sunlight remains visible during eclipse.
4. Hybrid eclipses: These are a rare form of Solar eclipse, which changes from an annular to a total solar eclipse along its path.
5.Lunar eclipse: A lunar eclipse occurs when the shadow of the earth falls on the moon. It occurs only on full moon day.
Types of lunar eclipse
1. Total Lunar eclipse: It occurs when the earth’s shadow(Umbra) obscures all of the moon’s visible surface.
2. Partial Lunar eclipse: It can be observed only when part of the moon’s visible surface is obscured by the earth’s shadow.
3. Penumbral Lunar eclipse: It happens when the moon travels through the partially shaded outer region of the shadow cast by the earth(earth’s penumbra).
The solar system:
The sun and the celestial bodies which revolve around it form the solar system. It
consists of large number of bodies such as planets, comets, asteroids and meteors. The gravitational attraction between the sun and these objects keeps them revolving around it.The earth revolves around the sun. It is a member of the solar system. It is a planet.There are seven other planets that revolve around the sun. The eight planets in their order of distance from the sun are:
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
Let us learn about some members of the solar system.
The Sun is the nearest star to us. It is continuously emitting huge amounts of heat and light. The sun is the source of almost all energy on the earth. In fact, the sun is the main source of heat and light for all planets of our solar system.