which is the star nearest to the earth
Answers
Alpha Centauri A
Of the three stars in the system, the dimmest - called Proxima Centauri - is actually the nearest star to the Earth. The two bright stars, called Alpha Centauri A and B form a close binary system; they are separated by only 23 times the Earth - Sun distance.
Answer:
Alpha Centauri A
Of the three stars in the system, the dimmest - called Proxima Centauri - is actually the nearest star to the Earth. The two bright stars, called Alpha Centauri A and B form a close binary system; they are separated by only 23 times the Earth - Sun distance.
Explanation:
◉LET'S EXPLORE MORE
✯Stars
Stars are celestial objects that can produce their own light. They are extremely hot and extremely large. They are mostly made up of hydrogen gas with a little helium in them. The sun is also a star; the sun’s energy and light play one of the key roles in sustaining all forms of life on earth.
Stars produce light by nuclear fusion reactions that happen inside it. In this process hydrogen is converted into helium and energy is produced as a by-product. It is this energy that comes to us as light. The sun is near to us appears large and very bright in the sky. However, all other stars are extremely far away from us. So, they appear small and faint in the sky. In fact, many of these celestial bodies are hundreds times bigger than our sun in size and much brighter, but they don’t appear so because they are so far away from the earth.
They are present in the sky even during the day. We do not see them because the sun’s bright light hides them. There are billions of them in the universe, more than all the grains of sand in the earth!
✯Constellations of Stars:
- Because the earth revolves around its axis from west to east, the stars all appear to move east to west like the sun. In the night sky they seem to appear as groups called as constellations forming a particular pattern in the sky. In reality, stars in constellations can be billions of kilometres apart. They only appear to be close when viewed from the earth.
- Stars also have an immense gravitational attraction. It is this gravitational attraction that can keep planets in orbit around them.
- They are usually named by the constellation in which they appear. For example, the nearest star to the earth (other than the sun) is Proxima Centauri. It is named after the constellation Centaurus. Other very bright stars usually have names that don’t correspond to their constellation such as Polaris (Dhruva), Aldebaran (Rohini), Betelguese (Aardra), Castor and Pollux (Punarvasu), Regulus (Magha) and Spica (Chitra).
- When you look at the night sky, try identifying the individual stars of constellations. See if you can identify the brightest star, Sirius and the pole star, Polaris (Dhruva) by reading our article on constellations.
✯Seven Main Stages of a Star
☆1. Giant Gas Cloud
- A star originates from a large cloud of gas. The temperature in the cloud is low enough for the synthesis of molecules. The Orion cloud complex in the Orion system is an example of a star in this stage of life.
☆2. Protostar
- When the gas particles in the molecular cloud run into each other, heat energy is produced. This results in the formation of a warm clump of molecules referred to as the Protostar. The creation of Protostars can be seen through infrared vision as the Protostars are warmer than other materials in the molecular cloud. Several Protostars can be formed in one cloud, depending on the size of the molecular cloud.
☆3. T-Tauri Phase
- A T-Tauri star begins when materials stop falling into the Protostar and release tremendous amounts of energy. The mean temperature of the Tauri star isn’t enough to support nuclear fusion at its core. The T-Tauri star lasts for about 100 million years, following which it enters the most extended phase of development – the Main sequence phase.
☆4. Main Sequence
- The main sequence phase is the stage in development where the core temperature reaches the point for the fusion to commence. In this process, the protons of hydrogen are converted into atoms of helium. This reaction is exothermic; it gives off more heat than it requires, and so the core of a main-sequence star releases a tremendous amount of energy.
☆5. Red Giant
- A star converts hydrogen atoms into helium over its course of life at its core. Eventually, the hydrogen fuel runs out, and the internal reaction stops. Without the reactions occurring at the core, a star contracts inward through gravity causing it to expand. As it expands, the star first becomes a subgiant star and then a red giant. Red giants have cooler surfaces than the main-sequence star, and because of this, they appear red than yellow.
☆6. The Fusion of Heavier Elements
- Helium molecules fuse at the core, as the star expands. The energy of this reaction prevents the core from collapsing. The core shrinks and begins fusing carbon, once the helium fusion ends. This process repeats until iron appears at the core. The iron fusion reaction absorbs energy, which causes the core to collapse. This implosion transforms massive stars into a supernova while smaller stars like the sun contract into white dwarfs.
☆7. Supernovae and Planetary Nebulae
