Celestial Bodies - Definition, Classification, Practice problems, FAQs

A celestial body is a phenomenon occurring naturally in space. While talking about space and galaxy, object and bodies are the two words that can be interchangeably used. Celestial bodies refer to strongly bonded entities that have complex shape and structure and consist of hundreds of sub-objects inside them. Celestial bodies can also be termed heavenly bodies and are objects in space such as the sun, moon, stars, and planets. In this article, we will discuss celestial bodies and their types.

Table of contents

• Definition of celestial bodies
• Stars
• Planets
• Satellites
• Comets
• Asteroids
• Meteors and Meteorites
• Galaxies
• Practice problems
• FAQs

Definition of celestial bodies

Celestial objects are located at quite large distances from the earth. They are part and parcel of the universe. Most of the heavenly groups can only be viewed using a telescope. They are mostly visible in the night sky and cannot be seen through the naked eye. Some celestial bodies are as big as the earth and some are even bigger. They are located outside the earth’s atmosphere. The Kuiper belt holds millions of celestial bodies.

Stars

Spheroid plasma constitutes the core of a plasma. It is held up together tightly with the help of its gravitational force. The Sun is also an example of a star. The sun has the least proximity from the earth. During nighttime, millions of small stars become visible to the naked eye. Throughout history, some of the most noticeable stars were grouped into asterisms and constellations. They all appear very tiny to our eyes because of the distance from the earth to the stars. However, they are in fact, more huge– some are even bigger than earth and other planets in the solar system.

Planets

A planet is a huge body that revolves around a star. Its shape is huge enough to be called a sphere but not big enough to cause a thermonuclear fusion. The word planet comes from the Greek word “Planetes” which refers to “wanderer”. During ancient times, the naked eye could view five planets in our solar system. But as technology developed, we are becoming aware of the fact that planets transform into many dissimilar bodies. At present, there are 8 planets in the solar system- they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

Satellites

A satellite is defined as a natural celestial object that revolves in a certain orbit around a planet. A satellite can be regarded as a part of the solar system itself. Few satellites are quite close to earth, about a few hundred kilometers away. The moon is an example of a natural satellite. A total of six terrestrial satellites are present in the solar system. As of September 2018, new research has proven that there are about 334 planets and they all have their own natural satellites.

Comets

A comet is an icy body present in the solar system. A comet becomes warm and starts to emit gasses when it gets closer and closer to the sun. This phenomenon of releasing gasses is known as out-gassing. This in turn creates a visible atmosphere, coma and rarely, even a tail. This happens because of the radiation from solar rays and the solar wind that acts along with the comet’s core.

The below figure shows a Haley’s comet. It is visible from the earth only every 76-79 years.

Asteroids

Asteroids can be termed minor planets, mainly since they are present inside the solar system. Big asteroids are called planetoids. These terminologies were historically used to describe any astronomical body which orbited around the sun. Asteroids are different from other bodies such as meteoroids and comets. Asteroids are relatively closer to the sun than any other celestial body. Hence, this prevents the formation of cometary ice.

Meteor and Meteorites

A shooting star can also be termed a meteor. The trajectory it follows is visible to the naked eye. These bodies enter our atmosphere when they are pulled by the earth’s gravity. They appear small and they burn up as they enter into the atmosphere of the earth. If the meteors are big enough to reach the ground, and can form a crater, which are called meteorites.

Galaxies

A large cluster of stars held together with gravitational force is termed a galaxy. For instance, the sun and the planets present in the solar system form a galaxy and it is called the Milky Way galaxy. On the other hand, the other galaxies are very far away and cannot be viewed through the naked eye.

Practice problems

Q1.What is astronomy?
Answer. The study of celestial bodies and the phenomenon associated with them is called astronomy. It talks about stars, planets and the moon. Astronomers base their studies on research and observation. Astrology talks about the position of planets and stars and their impact on a person’s life.

Q2.Define solar system.
Answer. The solar system includes all celestial bodies i.e Sun, planets, asteroids, comets and meteors.The major planets in the solar system are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Q3.Define constellation.
Answer. A group of stars that have a recognizable shape and those which can be studied is called a constellation. Some noteworthy stars are Orion the Great Hunter, Leo the Lion, or Taurus the Bull.

Q4. Give examples of a few galaxies?
Answer. A few examples of galaxies would be Andromeda, Cygnus A, Milky Way and Virgo A. The Virgo A is a huge cluster of mini galaxies(about 1300 to 2000 galaxies) . The Andromeda Galaxy, also called the Andromeda Nebula, is barely visible to the naked eye.

FAQs

Q1.What type of objects are considered celestial objects?
Answer. Celestial bodies are also called heavenly bodies. They include bodies in space such as the sun, moon, planets, and stars. The sun is the universal source of heat. The earth revolves around the sun and takes 365 days to complete one full orbit.

Q2.Which celestial bodies can be observed from the earth?
Answer. When viewed from the earth, in the daytime, we can observe the Sun. In the night time, we can observe the moon. Not just the moon, but about 2000 stars as well. In cities, pollution makes it difficult to see stars.

Q3.Give an example of a non-celestial body?
Answer. The aeroplane is an example of a non celestial body. It is man made, and is not a part of space. Planes fly in the inner atmosphere–they do not form a part of space. Hence, aeroplanes are examples of non-celestial bodies.

Q4.Are stars celestial bodies?
Answer. Stars are huge celestial bodies. They are primarily made of hydrogen and helium and produce light and heat from nuclear reactions going on inside them. These stars are located at distances about light years from the earth.