The Universe
The universe consists of the Earth, planets, space, stars, and galaxies. In 1929, American astronomer Edwin Hubble discovered that the universe is expanding. Hubble discovered that not only are galaxies outside the Milky Way moving away from each other, but also that those that are further away are moving away faster.
The Milky Way
The Milky Way is our parent galaxy (constellation) that contains the Sun. It is believed that there are more than two billion stars in the Milky Way. In addition, thousands of star dust lanes and nebulae are included in this circular galaxy. The Milky Way is estimated to have a mass of 750 billion to one hundred million times that of the Sun. The diameter of the galaxy is one hundred thousand light years. The Milky Way is part of the Local Group, a group of galaxies that includes three giant galaxies and 30 smaller galaxies. The Milky Way is the second largest galaxy in this group after the Andromeda Galaxy. The center of the Milky Way is found to be a supermassive black hole. The Sun is located 25,000 light-years from the center of the galaxy. The Sun is located in the Orion Ring, one of the Milky Way's 'rings'. The Sun orbits the center of the Milky Way at a speed of 225 kilometers per second. The time it takes the Sun to orbit the Milky Way once is called a 'cosmic year'. It is 226 million years.
Andromeda Galaxy
Andromeda is a neighboring galaxy to the Milky Way. It is also known as M31. It is a ring galaxy. It is located 2.5 million light-years from Earth. In other words, the Andromeda we observe is 2.5 million years old.
Nebula
Nebulas are clouds of gas and dust between stars in galaxies. This is where stars are born.
Quasars
Quasars are the most distant objects ever discovered in the universe. 'Quasar' is short for 'quasi-stellar radio sources'. Researchers have concluded that quasars are supermassive black holes with the mass of billions of suns.
Solar System
The Solar System is a system that includes the Sun, eight planets, moons, dwarf planets, comets, meteorites, asteroids, Kuiper Belt objects, dust clouds, and millions of other small and large objects. The planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Sun and the Moon
The center of the solar system is the Sun. The source of energy for the solar system is the Sun. In the Sun, the process of nuclear fusion takes place, where hydrogen atoms combine to form helium. It takes 226 million years for Sun to orbit the center of the Milky Way. This is called a cosmic year.
The Moon is the fifth largest satellite. The Moon takes 27 days, 7 hours and 43 minutes to orbit the Earth. Selenology is the branch related to the study of the Moon. The color of the sky on the Moon is black because the Moon has no atmosphere.
Stars
Stars were formed when atoms came together when the universe began to expand. They are the basic building blocks of galaxies. A star is a large ball of gas that emits heat and light. They are born in clouds of gas and dust in galaxies. Each galaxy contains billions of stars. Nuclear fusion takes place in stars. Stars are giant, glowing balls of plasma. Except for hydrogen and helium, all other heavier elements are created in stellar cores. Stars typically live for billions to billions of years. The mass of stars is the main factor that determines their luminosity. The oldest star discovered so far is 'HE 1523-0901'. It is 1.32 billion years old. The lifespan of stars decreases as they get bigger. This is because the inner core of larger stars experiences extreme pressure due to high gravity. Therefore, hydrogen burns out quickly. However, stars with finite masses burn out very slowly. The factor that determines the end of stars is their mass. Neutron stars, black holes, and white dwarfs are names used to indicate the states in which stars reach their end. Stars are classified based on their composition and temperature. They are classified based on temperature as O, B, A, F, G, K, and M. O and B are uncommon. However, they are very bright. M stars are common and dim. The hottest stars are in the O group and the coolest are in the M group. Each group is further divided into sub-groups, numbered from zero to nine.
■ O category - blue - 30000 K - 50000 K,
■ B category - blue-white - 9500 K - 30000 K,
■ A category - white - 7000 K - 9500 K,
■ F category - yellow - white - 6000 K - 7000 K,
■ G category - yellow - 5200 K - 6000 K,
■ K category - orange - 3900 K - 5200 K,
■ M category - orange - red - 2000 K - 3900 K
Comets
Comets are small objects that orbit the Sun in the Solar System. Despite their name, comets do not have tails most of the time. The most constant feature of a comet is its head (nucleus). It is a small object. When viewed through a telescope, it resembles a star. Asteroids and comets differ in two ways. In terms of orbit and chemical composition. Comets have very circular orbits. In terms of chemical composition, it is believed that the head of a comet is mostly frozen water. Comets are impure icy objects.
When approaching the Sun, some of the water evaporates, which forms a tail. The first scientist to attempt a scientific understanding of comets was Edmund Halley. He calculated the orbits of 24 comets. Using a method developed by Isaac Newton, he predicted that the comet that bears his name would return once every 76 years and that it would return again in 1758. This turned out to be correct.
After appearing in 1758/59, Halley's Comet returned in 1835, 1910, and 1986. However, many comets come close to us over a long period of time. In 1970, the very bright Comet Bennett passed close to Earth. It will not return again until 1700 years later. Comet West, which appeared in 1976, will have to wait another half a million years.
Meteoroids
Asteroids are small planets that orbit the Sun. Most asteroids in the solar system are found between Mars and Jupiter. Sometimes asteroids collide and break off into small pieces. These pieces are called meteoroids or meteoroids. They are dangerous space objects that enter the atmosphere of planets. When they enter the Earth's atmosphere, they collide with the air and burn up. They are also called 'shooting stars' because they appear as streaks of light in the sky. Sometimes meteoroids do not burn up completely. In that case, the rest falls to Earth. These are meteoroids.
Meteoroids are also known as shooting stars. Meteoroids are the streaks of light that are formed when meteors burn up when they enter the Earth's atmosphere. Meteoroids are the fragments of asteroids that fall to Earth. Hobawest (weight - 60 tons) is the largest meteorite that fell on the Earth's surface (in Namibia in 1920). Comet debris is also a type of debris that enters the Earth's atmosphere and burns up in the heat caused by friction in the air and disappears in the atmosphere.
Dwarf Planets
Dwarf Planets are spherical little bodies found in the solar system. There are currently five dwarf planets in the solar system. Eris, Cyrus, Makemake, and Haumea in the Kuiper Belt beyond Neptune are all dwarf planets. Pluto is one of these. Pluto was discovered in 1930 by an American astronomer named Clyde Tombaugh. Located in the Kuiper Belt, this body was given the status of the ninth planet by the International Astronomical Union (IAU) in February 1999. On August 24, 2006, the IAU revoked Pluto's planetary status and reclassified it as a dwarf planet. Charon is the largest body orbiting Pluto. Nix, Hydra, Charon, Kerberos, and Styx are also moons orbiting Pluto. Trans-Neptunian objects orbit the Sun beyond Neptune. Examples include Sedna, Quaovar, and Varuna.
Asteroids
Asteroids are rocky objects, such as asteroids, that are found between Mars and Jupiter. The region in which they are found is called the asteroid belt. It is believed that these are the remains of a planet that has broken up. That is why they are also called asteroids. Cirrus is the largest asteroid. There are asteroids named C.V. Raman, Chandra, Hanuman, Garuda, and Aruna. Cirrus is now classified as a dwarf planet. The asteroid 1950 DA has been found to have a chance of hitting Earth on March 16, 2880. Asteroids, like planets, are also orbiting the Sun in a fixed orbit. On February 14, 2001, the spacecraft NEAR landed on the asteroid Eros. The word asteroid was first used by William Herschel in 1802. Asteroids have also been named after the new generation of Indians like Akshat Singh, Anupama Kotha, Neeraj Ramanathan, Padmanabhan and Harish Chandra. A asteroid has been named after the Malayali environmentalist Zainuddin Pattazhi. Its name is '5178 Pattazhi'.
Satellites
Natural satellites are non-human objects that orbit a planet or a larger celestial body. Satellites can orbit planets, dwarf planets, or even asteroids. There are 240 such satellites found in the solar system. Of these, 169 orbit planets, 8 orbit dwarf planets including Pluto, and the rest orbit small objects in the solar system. Seven of the solar system's satellites, including the Moon, are larger than 3,000 kilometers across. In addition to the Moon, the Galilean satellites of Jupiter are Io, Europa, Ganymede, and Callisto, as well as Saturn's moon Titan and Neptune's Triton. The Galilean satellites of Jupiter are the first satellites to be recognized by humans after the Moon. They were discovered by Galileo in 1610. Titan was discovered by Christiaan Huygens.
Moon Landing
The space age reached a new milestone with the landing of man on the moon; on July 20, 1969 (July 21, Indian time). Neil Armstrong, who arrived in the American 'Apollo 11' vehicle, set foot on the moon. Edwin Aldrin and Michael Collins were Armstrong's co-passengers on Apollo 11. Apollo 11 soared to the moon, which was approximately 3,84,400 km from Earth. Michael Collins was the pilot of the main vehicle of Apollo 11, Columbia. While Collins was controlling the main vehicle, Neil Armstrong and then Edwin Aldrin landed on the moon at 8.26 am on July 21, 1969. The two were taken to the lunar surface by the small vehicle 'Eagle' from Apollo. The two landed in the 'Sea of Tranquility' on the lunar surface. Due to the low gravity, walking on the moon was very difficult for them. Before returning, they collected soil and rocks from the moon. They returned to Earth safely by boarding the main vehicle.
By 1972, five more Apollo missions had landed men on the moon. A total of twelve people had landed on the lunar surface. They reached only a few kilometers from the lunar surface. There were also those who returned in orbit. 14 people who went on Apollo-8, Apollo-10, Apollo-13, and other Apollo missions have returned in this way. Two of them later landed on the moon in other Apollo vehicles. About four hundred thousand scientists worked behind the Apollo success. Although astronauts planted the American flag on the moon, a 1967 international law states that no country can claim ownership of any planet, satellite, or star in space.
The oldest and youngest person to land on the moon Alan Shepard is the oldest person to land on the moon. He was 47 years, 2 months, and 18 days old when he landed on the moon in February 1971 on Apollo 14. Charles Duke is the youngest person to land on the moon. Duke was 36 years, 6 months, and 18 days old when he landed on the moon in Apollo 16 in 1972.
The 12 people who walked on the moon: Neil Armstrong and Edwin Aldrich (Apollo 11, July 21, 1969), Pete Conrad and Alan Bean (Apollo 12, November 19–20, 1969), Alan Shepard and Edgar Mitchell (Apollo 14, February 5–6, 1971), David Scott and James Irwin (Apollo 15, July 31–August 2, 1971), John W. Young, Charles Duke (Apollo-16, April 21–23, 1972), Eugene Cernan, Harrison Schmidt (Apollo-17, December 11–14, 1972)
International Space Station (ISS)
The International Space Station is the second brightest object visible to the naked eye from Earth after the Moon. It orbits 400 km above Earth. It travels at a speed of 17,500 miles per hour. In the late 1960s, the Soviet Union began efforts to establish a space station, abandoning lunar exploration. This began with the launch of the Salyut satellite system in 1971. The Salyut mission ended in 1982 with the launch of Salyut-7. It was followed by the Mir space station.
The first module of the space station, 'Zarya', was launched on November 20, 1998. Russia launched the 'Zarya' module into an orbit of 420 km altitude using a Proton rocket from the Baikonur Cosmodrome in Kazakhstan. Two weeks later, in December 1998, the module Unity was attached to 'Zarya' by the passengers of the space shuttle Endeavour. The ISS was completed by launching different parts into space at different times and assembling them. The space station is divided into two parts. The Russian Orbital Segment (ROS) and the United States Orbital Segment (USOS). The operations and experiments of the International Space Station are carried out by a joint effort of NASA, the Russian Federal Space Agency (ROSCOSMOS), the Japan Aerospace Exploration Agency (Jaxa), the European Space Agency (ESA), and the Canadian Space Agency.
Solar Eclipse
A solar eclipse occurs when the shadow of the Moon falls on the Earth. This shadow travels across the Earth's surface at a speed of 3200 km per hour. Solar eclipses are divided into three types.
1. Total solar eclipse: The sun is almost completely blocked from view. Although a total solar eclipse can last up to 7 minutes and 40 seconds, the average duration is two and a half minutes. During a total solar eclipse, the Moon's shadow, which is about 10,000 miles long, passes across the Earth's surface. It is only about 100 miles wide. This shadow path that the Moon casts on the Earth is called the 'Path of Totality'. The Sun's corona can only be seen during totality. The diamond ring effect is a beautiful sight that occurs when the Sun's rays come out through the low points on the Moon's surface during a total solar eclipse. Also known as Bailey's Beads.
2. Annular solar eclipse: When a solar eclipse occurs when the Moon is at its farthest from the Earth, the center of the Sun is darkened and a ring of sunlight is visible around it. This is an annular eclipse. The longest annular solar eclipse of this century occurred on January 15, 2010. Its maximum duration was 11 minutes, 7.8 seconds.
3. Partial solar eclipse: A partial solar eclipse occurs when the Moon partially blocks the view of the Sun.
Lunar eclipse
This is a condition in which the Moon becomes partially or completely invisible when the Earth's shadow falls on the surface of the Moon. Even during a total lunar eclipse, the Moon's appearance does not completely disappear. The Moon has a red color due to the red rays that are separated from the light that is refracted by the Earth's atmosphere. Thus, a lunar eclipse becomes a red moon. Lunar eclipses occur only on the days of the White Moon. The maximum duration is one hour and 40 minutes.
Saros Cycle
The Saros Cycle refers to a cycle of eclipses. It is a period of 18 years, 11 days, and 8 hours (6585.3 days). Using the Saros Cycle, eclipses can be predicted. This eclipse cycle was invented by the ancient Babylonians.
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