Stars are gigantic luminous celestial spheres of gas that glow by radiation generated from their internal energy sources. The closest star to the Earth is the Sun.
The aggregate mass of a star is the predominant component that controls its growth and eventual end. The life of a star starts with the gravitational collapse of a nebula made of hydrogen, helium and meagre quantities of heavier elements. During most of its thriving life, a star glows due to the nuclear fusion of hydrogen into helium. This results in a massive ejection of energy that radiates into space.
The core develops into a stellar residue at the end of its lifetime. Depending on the star’s mass, it could become a black hole, white dwarf, or neutron star. A star with a mass above 1.44 times the solar mass does not become a white dwarf. Instead, it continues to disintegrate and explodes into a supernova. In the end, it transforms into a neutron star.
Here is an engaging video about stars!
Important Stars Questions with Answers
1) What is a star?
A star is a gigantic luminous celestial sphere of gas that glows by radiation generated from its internal energy sources. They are massive glowing spheres of plasma glued together with their own gravity. During most of its thriving life, a star glows due to the nuclear fusion of hydrogen into helium. This results in a massive ejection of energy that radiates into space.
2) Which is the closest star to the Earth?
The Sun is the closest star to the Earth.
3) What is the distance between the Sun and the Earth?
The distance between the Sun and the Earth is 147.73 million kilometres.
4) Which is the nearest star to the Solar System?
Proxima Centauri is the nearest star to the Solar System.
5) How far is Proxima Centauri from the Earth?
4.246 light-years is the distance between Proxima Centauri and the Earth.
6) Why do stars twinkle in the night sky?
In reality, stars do not have the ability to twinkle. Due to various optical phenomena, stars appear to be blinking in the night sky. As stars are far away from the Earth, the intensity of their light is very low. If there is any obstruction in their path, the low-intensity light rays wobble and constantly change their optical attributes. These changes are reflected as twinkling and colour flickering. When starlight penetrates the Earth’s atmosphere, it is always obstructed by different layers of the atmosphere. Each layer has its own density and temperature. When light travels through a medium with different densities, refraction occurs. Here also, such optical illusions happen.
7) How many stars can be observed in the night sky?
On the upper-end estimation, there are about ten-thousand visible stars in all directions. Another analysis points out that there are about five-thousand stars visible to the eye. However, half of the Earth is in the daylight every time. So real-time numbers may vary.
8) How many stars are there in the Universe?
We cannot calculate the exact number of stars in the Universe. Hubble Telescope’s deep field images indicated that there are close to two trillion galaxies in the observable Universe. According to the new estimates, about a hundred million stars exist in an average galaxy. So, there are about two-hundred billion trillion stars in the known Universe.
9) Which is the brightest star in the night sky?
Sirius (Sirius A or Dog Star) is the brightest star in the night sky.
10) What is the lifespan of stars?
The lifespan of stars depends on their mass, density and temperature. An average star like the Sun lives for around ten billion years. Stars with 20 times the solar mass can only live for ten million years. Therefore, the more massive a star is, the shorter its lifespan.
11) What are constellations?
Constellations are groups of stars that resemble recognisable shapes in the night sky.
Some stars in a constellation might be close, and some might be far away from each other. When we draw lines joining these stars in the sky, we should get shapes resembling animals, persons or objects. Since the dawn of human civilisation, many constellations have been sketched out. They have various names, depending on the region.
Some of the famous ones are Ursa Major, Ursa Minor, Orion, Taurus, Gemini, etc.
12) How many constellations are there in the night sky?
In the course of history, many cultures had their own collection of constellations, based on what humans saw at that time. Currently, there are about 88 officially identified constellations.
13) Are the positions of constellations permanent?
The movement of celestial bodies causes constellations to alter their structure over time. However, it may take a long time for people to notice those changes. Edmond Halley discovered stars that were stated in old Greek star charts. Surprisingly those changed their position slightly 1,600 years later.
14) Which is the most common type of star in the Universe?
Red dwarfs are the most common type of star in the Universe.
15) Can a star engulf the planet Saturn?
Yes, some of the biggest stars can easily engulf Saturn.
16) Which stars have the shortest lifespan?
The most massive stars have the shortest lifespan.
17) Which device is used to observe faint stars which are not visible to the naked eye?
Powerful telescopes are used to observe faint stars that are not visible to the naked eye.
18) When can we observe the maximum number of stars at a time?
We can only observe about two-thousand stars on a dark night. Furthermore, the spot must be far away from the sources of light pollution (cities and industries). For this purpose, we should choose a moonless night for observing the sky.
19) Where do new stars form?
Stars are formed in the clouds of gas and dust scattered all over most galaxies. Nebulae are the hotspots of such clouds.
20) Which are the four main stars we know?
Sun, Proxima Centauri, Alpha Centauri and Sirius.
21) What is the age of the Sun?
The Sun is about 4.5 billion years old. It is considered to be a middle-aged star.
22) Which is the oldest star chart in history?
The oldest star chart was used in ancient Egyptian astronomy (1534 BC).
23) When did Chinese astronomers observe the first-ever supernova?
In 185 AD, Chinese astronomers recorded the first-ever supernova.
24) The furthest distance a single star has been detected from is around _____ light years.
Answer: 100 million
Explanation: The furthest distance a single star has been detected from is around 100 million light years.
25) What are the main types of stars in the Universe?
The main types of stars are:
- Yellow Dwarf Stars
- Red Dwarf Stars
- Orange Dwarf Stars
- Brown Dwarfs
- Red Giant Stars
- Blue Giant Stars
- White Dwarfs
- Red Supergiant Stars
- Black Dwarfs
- Neutron Stars
26) What is a nebula?
A nebula is a giant interstellar cloud of hydrogen, ionised gases, helium and dust. Some of these materials came from the remains of dead stars. When a star dies, it probably explodes and throws out dust and gases. Nebulae are also known as “star nurseries”. New stars are generally created from massive nebulae. Depending on the density of nebulae, different types of stars are formed.
27) What is Chandrasekhar Limit?
At the end of a star’s lifetime, its core develops into a stellar residue. Depending on the star’s mass, it could become a black hole, white dwarf or neutron star. The Chandrasekhar limit sheds light on this process. A star with a mass above 1.44 times the solar mass does not become a white dwarf. Instead, it continues to disintegrate and explodes into a supernova. In the end, it transforms into a neutron star.
28) Explain the formation of stars.
Stars are usually formed in the interstellar clouds called “nebula”. They are mostly made of molecular hydrogen, usually mentioned as HII regions. The process starts when the cloud is pushed into a spinning movement (it may be due to external reasons like a supernova explosion, gamma-ray bursts, etc.). Then compressed clumps of gas and dust are formed. They become hotter and hotter as they accumulate more mass. When the internal temperature of such baby stellar objects crosses ten million degrees Celsius, a reaction called nuclear fusion begins. This ignition marks the birth of a star.
29) How do stars die?
Stars have life spans ranging from tens of millions to billions of years. The nature of a star’s death relies on the inherent mass formed during its whole lifetime. Stars with matter identical to the Sun disintegrate differently from stars with seven times or larger solar masses. Yet, the fundamental and common reason for every star’s end is the same: lack of fuel to burn. During most of its life stars fuse hydrogen to produce helium. When it runs out of hydrogen, they fuse helium and then carbon. Every level of fusion emits more energy, which increases the star’s temperature.
Stars that are way more massive than the Sun carry on with fusion reactions. The process continues until they get to a point where the core collapses. The external layers also disintegrate onto the core and then bounce out to space in a cataclysmic explosion known as a supernova.
30) What happens to a star after it dies?
When a star dies or explodes, all the elements generated in the core are thrown out to space. It will probably become part of the interstellar clouds of dust and gas. Such elements will become the raw material for newborn stars, planets, and smaller celestial bodies. In fact, every element in our body was once created from the core of a star. We are made of stardust.
Practice Questions
1) What is the age of the Sun?
2) Which is the most common type of star in the Universe?
3) Which is the nearest star to the Solar System?
4) What is the distance between the Sun and the Earth?
5) What are constellations?
|
Related Topics |
|---|
Stay tuned to BYJU’S and Fall in Love with Learning!
Comments