Astrophysics is the major subject to develop knowledge about celestial objects. The study of the sun, the comets, the stars, asteroids, meteoroids, and galaxies is called astrophysics. The birth of the stars and their life and the end of the stars are studied through this. Asteroids are small celestial objects which orbit around the sun. The orbit of the asteroid is in between Mars and Jupiter. A comet contains small rigid material. This material is covered by substances with high masses.
Water, methane, and ammonia are the substances that cover the material. These substances are easily vapourised. It rotates the sun in an elliptical orbit and it keeps the distance high from the sun. The maximum distance it approaches the sun radiant energy of the sun heats the comet and vapourises materials contained in it. So it forms into a huge comet with a diameter of 10000km. The partially burnt pieces of the asteroids that fall on the earth are called meteoroids.
Small planetary bodies orbit around the Sun are Asteroids. These Asteroids are in between the orbit of Jupiter and Mars. A Group of Asteroids in orbit is called Asteroid belts. It consists of millions of Asteroids. The asteroid belt contains almost 7,00,000 asteroids in it. Only 1600 asteroids are revolving around the Sun. 700km radius is the highest radius of the asteroid. It is named Ceres. It takes four and half years to circle the Sun. Asteroids apply a gravitational pull because of their huge size. So they didn’t have an atmosphere. Jupiter’s mass gravity and close encounters with Mars change the orbits of asteroids. Due to the close encounters with Mars, asteroids pulled out from the asteroid belt and roamed in any direction across the orbit of other planets. The name of an asteroid is given by the International Astronomical Union’s Committee on Small Body Nomenclature.
Fig:1 Asteroid hitting earth
The composition of Asteroids is classified into three types. The distance from the Sun decides the composition of the asteroid. The difference in composition is dependent on the distance of the asteroid from the Sun. The oldest asteroids are C-type asteroids. It is a combination of silicate rock and clay. This asteroid has a very dark appearance. These are the most common asteroids. Metallic types of asteroids are a combination of nickeliron. These are called M-type asteroids. The nickel-iron and silicate materials combine and form S-type asteroids.
Asteroids are classified into three types.
Main Asteroid Belt − Group asteroids are known as asteroid belts. This asteroid belt is in the middle of the orbits of Jupiter and Mars. The asteroid belt consists of a million large asteroids and a million small asteroids. The average diameter of large asteroids is 1 kilometer.
Trojans − Asteroids pulled out from the asteroid belt and in orbit with other planets are called Trojan asteroids. These asteroids do not collide with the planets. It has two special places in orbit. These two places are called Lagrangian points.
Near-Earth Asteroids − These asteroids orbit close to the Earth’s orbit. Asteroids that cross the Earth’s orbital path are known as Earth-Crossers.
There is no shape for an asteroid. But most of the asteroids are in a spherical shape that too have many shape-outs. Asteroids have rough surfaces and holes in their surface.
It rotates the Sun in an elliptical orbit. But sometimes it rolls unevenly when it rotates against the Sun.
Some asteroids have a small companion moon. Some asteroids have two companion moons.
When a comet reaches close to the sun it breaks apart into small pieces. While crossing the Earth’s orbit, these broken pieces fall on Earth. Because of the friction in the Earth’s atmosphere, some of the pieces are burnt. They are called meteorites.
A big piece from the broken comet will fall on earth when it crosses Earth’s orbit due to heat in the earth’s atmosphere. Some of the pieces are not fully burnt. These partially burnt pieces fallen on earth are known as Meteoroids.
Fig:2 Meteriod
The meteoroid consists of silicates, oxygen, and some heavier metals. Iron and nickel are the heavier metals contained in meteoroids. These meteoroids are not broken. But some stone meteoroids will be breakable and have less density. A clash of two asteroids produces a meteoroid.
The density of the meteoroid is higher than the Earth's rocks. Because it consists of iron and nickel. Many meteoroids consist of a thumbprint shape of pits in them. There are no holes in meteoroids. The shape of the meteoroid is not round. It is also called shooting stars.
| Meteoroid and Meteors | Comet |
|---|---|
| The partially burnt pieces of the asteroids that fall on the earth are called meteoroids. | Comets are large objects consisting of lighter mass materials. |
| Meteor is visible without a telescope. | Some of the comets are visible to the naked eye. For example Halley’s comet. |
| It consists of oxygen, silicates, and heavy materials like iron-nickel. | It is a cosmic object consisting of water ammonia and methane. |
| A clash of two asteroids produces a meteoroid. | Comets are formed by the remaining frozen of the formation of solar systems. It consists of rock and ice or snow. |
Asteroids are small celestial objects which orbit around the sun. The orbit of the asteroid is in between Mars and Jupiter. A Group of Asteroids in orbit is called Asteroid belts. It consists of millions of Asteroids. A comet contains small rigid material. This material is covered by substances with high masses. Water, methane, and ammonia are the substances that cover the material. The broken piece of a comet falling on Earth is called Meteoroid. The moon, Mercury, and Mars have craters because the meteoroids hit the surface of these planets. A clash of two asteroids produces a meteoroid.
Q1. What are the types of Stars?
Ans.
Double and multiple stars
Intrinsically variable stars
Novae and super Novae
Q2. What is albedo?
Ans. Albedo is the ratio of the amount of solar energy reflected by the planet. The atmosphere of any planet depends on the value of albedo. For example, 0.85 is the albedo of Venus. So it has a higher atmosphere compared to other planets. The albedo of Mercury is 0.06. So there is no atmosphere on Mercury's planet.
Q3. Explain Halley’s Comet.
Ans. Some comets will travel in regular intervals. Halley’s comet will appear once every 75-76 years. The last time it was founded was in 1986. Before 1986 it was founded in 1910. This is the only periodic comet that is visible from the Earth. This is the only comet to see in the naked eye.
Q4. What are the conditions for life on any planet?
Ans.
The temperature range of the planet must be comfortable for living
The atmosphere of the planet must be sufficient
The amount of water on the surface of the planet must be considerable.
Q5. What are White Dwarfs?
Ans. A white dwarf is a small star that does not have the possibility of nuclear burning. It consists of a lighter element than iron.
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