Jasmine Grover Content Strategy Manager
Content Strategy Manager
Stars and Planets are both celestial bodies that are present in outer space. On a dark night, when you look up high in the sky, you see trillions of sparkling dots shining above. Some of them are brighter, some appear to twinkle, while some are larger than others. You might have wondered as a child what all the sky entails and what these bright spots are. Well, the shining dots above us are the stars and planets.
Stars are the celestial bodies, twinkling with their light. They have a fixed, massive luminous body, like the Sun. Planets, on the other hand, are celestial objects that have their apparent motion and orbit a star in an elliptical orbit. Planets spin around their own axis and do not have an internal source of light. Although stars and planets appear to be identical, there is a significant difference between stars and planets.
| Table of Content |
Key Terms: Stars, Planets, Gravity, Stars and Planets, Gases, Space, Elliptical Orbit, Rotation and Revolution
What are Stars?
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Stars are blazing balls of plasma that are held together by gravity. Plasma is a state of matter that is extremely hot. Gases such as hydrogen, helium, and other light elements make up the core of stars.
- Through nuclear fusion, the transformation of hydrogen into helium takes place which causes the stars to glow.
- The nuclear reactions that occur in stars continuously emit energy in the form of light throughout the universe, allowing us to detect and study them with a radio telescope.
Stars
- One of the prominent difference between stars and planets is that stars twinkle while planets do not
- The stars appear to twinkle as their light passes through the earth's atmosphere and undergoes atmospheric refraction.
- The Sun, which is about 150 million kilometers away from Earth, is the star closest to us.
- The distance between stars is measured in light-years, which is the distance light travels in a year.
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|---|---|---|
| Moon | Halley's comet | Difference between asteroid and meteoroid |
What are Planets?
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A planet is a celestial body that orbits the Sun and is smaller than the stars. It however has sufficient mass for its self-gravity to overcome the rigid body forces.
- The term "planet" refers to celestial bodies that orbit a star in a precise route.
- It is massive enough that its gravity causes it to take the shape of a spherical object, but not large enough to cause nuclear reactions.
- Our solar system's planets are split into two categories:
Inner Planets
Inner planets are planets whose orbits are contained within the asteroid belt. These are tiny, solid elements such as rocks and metals. Mercury, Venus, Earth, and Mars are among the planets that make up the Solar System.
Outer Planets
Asteroids orbiting outside the asteroid belt are known as outer planets. They have a ring around them and are larger than the inner planets. Gases such as hydrogen, helium, and others make up these planets. Jupiter, Saturn, Uranus, and Neptune are all outer planets.
Planets
Also Read: Variable star
Life Cycle of a Star
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Stars are born within dust clouds and are found across most galaxies. The Orion Nebula is a well-known example of such a dust cloud. In the blazons of spiral galaxies, stars develop as an impenetrable cloud of gas. Under the influence of the star's gravity, individual hydrogen atoms descend with a rising speed and energy into the cloud's center.
- Deep within these clouds, slubs of sufficient mass form, leading to a collapse of the gas and dust under their gravitational force.
- The increasing energy heats up the gas to a temperature of around 20 million degrees Fahrenheit after millions of years.
- The hydrogen within the star ignites and burns in a never-ending series of nuclear events at this temperature, and the material at the center begins to heat up.
- Our nearest star, the Sun, is so hot that a huge amount of hydrogen leads to a star-wide nuclear reaction. This reaction is identical to the one in the hydrogen bond.
- Even though it is constantly bursting in a nuclear reaction, the Sun and other stars are so massive that the explosion will take billions of years to consume all of the star's fuel.
- The inward force of gravity balances the exterior pressure of the gas heated by fusion, leaving the star in hydrostatic equilibrium.
- By keeping the star's temperature constant, this hydrostatic equilibrium remains balanced during the majority of the star's life.
- From birth to death, and all the stages in between, the life cycle of any star would take billions of years.
- That's why, to the fragment of our human eyes, these colossal giants don’t seem to change much.
Differences between Stars and Planets
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As the planets and stars both are celestial bodies in outer space, it is critical to understand the major differences between these two. A star is a body that emits light and reflects it to the observer. A planet, on the other hand, is a fixed celestial body that has its orbit and spins on its axis while reflecting light from another source. Planets do not have an internal source of light, thus they must rely on other sources, principally the Sun, for illumination. One of the primary difference between stars and planets is their size as stars are gigantic compared to planets. The difference between stars and planets are as follows –
| Stars | Planets |
|---|---|
| Stars are astronomical bodies that emit their light as a result of thermonuclear fusion occurring at their center. | Planets are celestial objects that have a set route (orbit) in which they move around a star. |
| Stars move at a tremendous rate in their orbits, but because of the great distance between them, their motion is only visible after a lengthy period of time. | Planets' positions constantly tend to shift as they orbit the sun on their axis. |
| Stars are dot-sized. | Planets are round-shaped. |
| In our solar system, there is only one star. While the galaxy is filled with trillions of stars. | Our solar system consists of eight planets. |
| Stars are formed of Hydrogen, Helium, and other light elements. | Planets are made up of solid, liquid, gases, or a combination of these states of matter. |
| The continual refraction of light in the earth's atmosphere causes stars to twinkle | Planets are closer to Earth, and light reflected from them goes straight through the atmosphere without bending, therefore they do not twinkle |
| Stars are hot and have a very high temperature. | Planets have relatively low temperatures. |
| As a result of the thermonuclear fusion in their core, stars emit their own light. | Planets do not have any light of their own and hence they only reflect the light they receive from the Sun. |
Also Read:
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|---|---|---|
| Dwarf Planets | Motion of Celestial Bodies | Why do the stars twinkle? |
| Rare Earth Magnets | Earth satellites | Asteroid and comet difference |
Things to Remember
- Stars are a blazing ball of plasma that is held together by gravity. Plasma is a state of matter that is extremely hot.
- A celestial body that orbits the Sun and is smaller than the stars but has sufficient mass for its self-gravity to overcome the rigid body forces is known as a planet.
- There are two types of planets in our solar system: outer planets and inner planets.
- Stars are born within dust clouds and are found across most galaxies.
- The hydrogen within the star ignites and burns in a never-ending series of nuclear events and the center begins to heat up.
- A major difference between stars and planets is that the continual refraction of light in the earth's atmosphere causes stars to twinkle. Planets, on the other hand, are closer to Earth, and light reflected from them goes straight through the atmosphere without bending, therefore they do not twinkle.
- Hydrogen, helium, and other luminous elements make up stars. Planets, on the other hand, are made up of solid, liquid, gaseous, or a combination of these states of matter.
Sample Questions
Ques. Why are the Milky Way's stars and planets on a flat plane rather than a ball of stars and planets surrounding the center? (2 marks)
Ans. The spinning motion is the reason behind the stars and planets being on a flat plane. The black hole that exists in the center of the Milky Way Galaxy pulls matter in from all directions. When the black hole is not spinning, matter just shoots straight towards it, but when it is spinning, the matter spins with it. This is because space-time exists.
All gravity bends space-time. For example, if you press your finger down on a piece of paper, it bends; now replace the finger with gravity and the paper with “space-time,” and you get the idea. Gravity bends space-time physically.
Ques. Is it true that stars and planets can only exist in galaxies? (1 mark)
Ans. No. In the "empty" space between galaxies, there are many stars and planets. However, planets and stars between galaxies are scarce when viewed from a "galactic" perspective.
Ques. Is the plane of all stars and planets the same? (5 marks)
Ans. Yes. With respect to our solar system, the plane on which all of the planets revolve around our sun is more or less the same. This is because they have been influenced by the gravitational and centrifugal forces of the sun since the beginning of their formation. The planets aligned themselves on an equatorial plane to the sun as a result of this.
Other stars visible in the night sky, on the other hand, are all around us at 360 degrees. They are separated by light-years of interstellar space. When contemplating the larger scale of our Milky Way galaxy, however, these stars and clusters are more or less orientated on the same plane. Almost 80% of known stuff is found on the arms of our galaxy, whereas lone stars reside in a slightly slanted plane to the galaxy's equatorial plane, all impacted by the gravity of our galaxy's supermassive black hole at its center.
Ques. Isn't it true that all stars and planets are electrically neutral? (2 marks)
Ans. Stars and planets are electrically neutral for all practical purposes. They include electrically active materials like plasma and have significant magnetic fields. Astrophysical objects, on the other hand, are electrically neutral.
This is because if you have a charge, it repels like charges and attracts opposing charges. At atomic levels, you can compute the distance at which this occurs.
Ques. What determines the visibility of the planets and stars? (3 marks)
Ans. It is mostly determined by two factors: your location in the hemisphere and the severity of light pollution in the area where you are looking at the night sky.
From Earth, you can view roughly 2,500 stars per hemisphere, for a total of about 5,000 stars under optimum conditions. Mercury is rarely visible, although Venus (known as the evening star), Mars, Jupiter, and Saturn are frequently visible and quite easy to identify in the night sky with the naked eye.
Ques. Will the Sun's leftovers be recycled to generate new stars and planets after it dies? (3 marks)
Ans. As the sun's core begins to fuse into iron, part of its mass will most likely 'puff off.' This is quite likely, if not certain, to be recycled into the next generation of stars. The remaining mass will disintegrate into a white dwarf. It will stay the same for a very long period once it is in that state. What happens next is a matter of discussion and speculation. It will eventually collide with other stuff and collapse into a black hole, according to theory. Black holes will eventually dissipate into hawking radiation. In the meantime, the cosmos will have expanded more, leaving that energy with little choice but on an indefinite journey.
Ques. Do the planets and stars have any influence on us? (2 marks)
Ans. Each body in the cosmos attracts every other body. They do so with a force that is proportional to the product of the masses of the body and inversely proportional to the square of their distance.
Ques. Why does the form of all planets and stars look the same? (3 marks)
Ans. The majority of objects in the cosmos aren't spherical because they lack the mass and gravity to overcome the physical strength of their materials; trillions of comets and asteroids in our solar system, for example, are strangely shaped.
Planets and stars, for example, are large enough to overcome their makeup and squeeze themselves into the roundest shape imaginable. Meanwhile, the centrifugal pseudo-force prevents the objects from collapsing, causing them to bulge at their equators by a certain amount, depending on the rotation rate.
Due to its massive gravity and relatively modest 25-day spinning period, the Sun is the roundest object in our solar system, deviating from its spherical shape by less than 0.001%.
Ques. Is it possible that some galaxies have completely devoured their stars and planets? (2 marks)
Ans. There are undoubtedly relics of galaxies that have swallowed all of their stars, planets, and other matter. Because the universe is nearly 13 billion years old, some of the tiniest galaxies may have already been consumed or swallowed up. We'd never be able to find out about those. The only thing remaining would be a gigantic or supermassive black hole. That resulting black hole could have been eaten by a larger black hole, which is notoriously difficult to locate.
Ques. What do galaxies orbit, if moons orbit planets, planets orbit stars, and stars orbit the core of galaxies? (2 marks)
Ans. Galaxies, and even superclusters of galaxies, can orbit each other. Over astronomical periods, however, galactic orbits and trajectories tend to be extraordinarily sluggish and unstable. They'll frequently be flung into space, ripped apart by collisions with other galaxies, or merged with other galaxies. Nothing appears to be orbiting the Milky Way. Although several minor galaxies orbit the Milky Way, it is on a collision course with the Great Spiral Galaxy in Andromeda (M31) and eventually other galaxies.
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