Space the mysterious zone name: anupreet kaur Roll number: o3 Class: vii
universe The universe is gigantic. It contains Earth, the planets, the stars, and everything else in outer space. The universe is so big that a spaceship could travel for billions of years without reaching the end of it. It might even go on forever!
galaxy Galaxy, a massive ensemble of hundreds of millions of stars, all gravitationally interacting, and orbiting about a common center. Astronomers estimate that there are about 125 billion galaxies in the universe. All the stars visible to the unaided eye from Earth belong to Earth’s galaxy, the Milky Way. The Sun, with its associated planets, is just one star in this galaxy. Besides stars and planets, galaxies contain clusters of stars; atomic hydrogen gas; molecular hydrogen; complex molecules composed of hydrogen, nitrogen, carbon, and silicon, among others; and cosmic rays.
Milky way <ul><li>The Milky Way is a huge group of stars called a galaxy. There are billions of stars in the Milky Way. The Sun and all nearby stars are part of the Milky Way Galaxy. There are also huge clouds of gas and dust in between the stars. New stars form in the clouds of gas and dust. </li></ul><ul><li>The Milky Way Galaxy is shaped like a thick disk turning in outer space . </li></ul>
WHAT ARE PLANETS? <ul><li>Planet, a round body in space that orbits a star. To be a planet, a body must be big enough to settle into a rounded shape from the inward pull of its own gravitation. A planet shines by reflecting light and not by releasing nuclear energy the way a star does. Our solar system has eight major planets—Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune—and a number of small, dwarf planets, including Pluto, Eris, and Ceres. A planet-like body that revolves around a larger planet is called a satellite or moon rather than a planet. Jupiter from Pioneer 10 </li></ul><ul><li>Planets are distinct from asteroids and comets, smaller bodies that also orbit stars. </li></ul>
stars <ul><li>A star is a big ball of hot, glowing gas. The gas is mostly hydrogen and helium. Stars give off heat, light, and other kinds of energy. </li></ul><ul><li>A star has several layers. The part at the center of a star is called its core. A star shines because of its core. The core is so hot and tightly packed that atoms crunch together. Atoms are tiny bits of matter much too small to see. Hydrogen atoms crunch together and become helium atoms. This is called nuclear fusion. Nuclear fusion gives off enough energy to make the stars shine. </li></ul>
SOLAR SYSTEM <ul><li>Solar System, the Sun and everything that orbits the Sun, including the planets and their satellites; the dwarf planets, asteroids, Kuiper Belt Objects, and comets; and interplanetary dust and gas. The term may also refer to a group of celestial bodies orbiting another star ( see Extra solar Planets). In this article, solar system refers to the system that includes Earth and the Sun. </li></ul>
The Sun <ul><li>The sun is in the centre of the solar system. It is huge and made up of extremely hot gases. It provides the pulling force that blinds the solar system. The sun is the ultimate source of heat and light for the solar system. But that tremendous heat is not felt so much </li></ul><ul><li>by us because despite being our nearest star, it is far away from us. The sun is about 150 million km away from the earth. </li></ul>.
<ul><li>THE eight PLANETS </li></ul>Mercury Mercury orbits closer to the Sun than any other planet, making it dry, hot, and virtually airless. Although the planet’s cratered surface resembles that of the Moon, it is believed that the interior is actually similar to Earth’s, consisting primarily of iron and other heavy elements. This composite photograph was taken in 1974 by Mariner 10, the first probe to study Mercury in detail.
VENUS <ul><li>Venus is the brightest object in our sky, after the sun and moon. Swirling clouds of sulfur and sulfuric acid obscure Venus’s surface and inhibited study of the planet from Earth until technology permitted space vehicles, outfitted with probes, to visit it. These probes determined that Venus is the hottest of the planets, with a surface temperature of about 460° C (about 860° F). Scientists believe that a greenhouse effect causes the extreme temperature, hypothesizing that the planet’s thick clouds and dense atmosphere trap energy from the sun. </li></ul>
EARTH <ul><li>An oxygen-rich and protective atmosphere, moderate temperatures, abundant water, and a varied chemical composition enable Earth to support life, the only planet known to harbor life. The planet is composed of rock and metal, which are present in molten form beneath its surface. The Apollo 17 spacecraft took this snapshot in 1972 of the Arabian Peninsula, the African continent, and Antarctica [most of the white area near the bottom]. </li></ul>
MARS <ul><li>The most detailed information available about Mars has come from unpiloted spacecraft sent to the planet by the United States. From this data, scientists have determined that the planet’s atmosphere consists primarily of carbon dioxide, with small amounts of nitrogen, oxygen, water vapor, and other gases. Because the atmosphere is extremely thin, daily temperatures can vary as much as 100 Celsius degrees (190 Fahrenheit degrees). In general, surface temperatures are too cold and surface pressures too low for water to exist in a liquid state on Mars. The planet resembles a cold, high-altitude desert. </li></ul>
Asteroid belt <ul><li>Asteroids are big pieces of rock and metal in space. There are thousands of them between Mars and Jupiter in an area called the asteroid belt. They go around the Sun just like planets do. </li></ul>
JUPITER <ul><li>Jupiter is the largest of the planets, with a volume more than 1,300 times greater than that of Earth. Jupiter’s colorful bands are caused by strong atmospheric currents and accentuated by a dense cloud cover. The massive planet, upper right, is shown here with its four largest satellites: Io, upper left , Ganymede, lower left , Europa, center , and Callisto, lower right. </li></ul>
SATURN Saturn, distinguished by its rings, is the second largest planet in the solar system. This processed Hubble Space Telescope image shows the planet’s cloud bands, storms, and rings as they would appear to the human eye.
Uranus <ul><li>Uranus’s blue-green color comes from the methane gas present in its cold, clear atmosphere. The dark shadings at the right edge of the sphere correspond to the day-night boundary on the planet. Beyond this boundary, Uranus’s northern hemisphere remains in a four-decade-long period of darkness because of the way the planet rotates. Scientists compiled this view of Uranus from images returned from Voyager 2 in 1986, when the probe was 9.1 million km (5.7 million mi) away from the planet. </li></ul>
Neptune This image of Neptune, taken by the Voyager 2 spacecraft, shows the planet’s most prominent features. The large, dark oval surrounded by white clouds near the planet’s equator is the Great Dark Spot, a storm similar to Jupiter’s Great Red Spot. The smaller dark oval with a bright core below and to the right of the Great Dark Spot is another storm known as Dark Spot 2.
<ul><li>The Kuiper Belt is a disk-shaped collection of small, icy objects in the outer solar system. The belt extends from just inside Neptune’s orbit far beyond the orbit of Pluto. </li></ul>Kuiper Belt
constellation People have grouped stars into imagined patterns, called constellations, since ancient times. Ancient people created these patterns to remember important people and events. Click on the arrows to learn more about some of the constellations that appear in the skies of the Northern Hemisphere. Following are the name of the constellations ,which people have grouped since ancient times:-
<ul><li>1. Big dipper- </li></ul><ul><li>The Big Dipper is a constellation of seven stars in the northern celestial hemisphere. It is also known by the names Ursa Major (the Great Bear), the Plow, Charles’s Wain, and the Wagon. In Hinduism, the seven stars in the constellation represent the seven rishis, or holy ancient sages. </li></ul>
<ul><li>Ursa Major is made up of many stars that appear to form the shape of a bear. Ursa Major contains the Big Dipper, a group of seven stars in the shape of a large cup with a long handle. The handle of the dipper forms the bear’s tail and the cup is located near the bear’s rear end. Ursa Major is best seen in the summer months. </li></ul>2. Ursa Major-
<ul><li>3. Pegasus- </li></ul>Pegasus (astronomy), northern constellation, situated southeast of Andromeda. The three brightest stars of Pegasus, α Pegasi, or Markab, β Pegasi, or Scheat, and g Pegasi, or Algenib, form a square with α Andromedae, called the square of Pegasus. The constellation, which is named for the winged horse of Greek mythology, is usually seen upside down in the sky, with only the head, neck, and front half of the animal represented by the stars.
<ul><li>4. Orion- </li></ul>Orion, named for a famous hunter in Greek mythology, is the brightest constellation in the winter sky. It includes eight bright stars in the shape of an hourglass. According to legend, three stars in a row form the belt of Orion.
<ul><li>5. Cygnus </li></ul>Cygnus (Latin, “swan”), prominent northern constellation that lies mostly within the Milky Way. Cygnus is seen best during early September, when it reaches its highest point in the evening sky. It contains the bright first magnitude star Deneb and a group of six stars that form a Latin cross known as the Northern Cross. Cygnus contains many interesting objects including 61 Cygni, the first star (other than the sun) to have its distance from earth calculated. Cygnus also contains one of the most powerful radio sources in the sky, Cygnus A and a strong X-ray source, Cyg X-1, thought to be a black hole.
Black hole <ul><li>Black Hole, an extremely dense celestial body that has been theorized to exist in the universe. The gravitational field of a black hole is so strong that, if the body is large enough, nothing, including electromagnetic radiation, can escape from its vicinity. The body is surrounded by a spherical boundary, called a horizon, through which light can enter but not escape; it therefore appears totally black. </li></ul>
comets <ul><li>Comet, small icy body in space that sheds gas and dust. Like rocky asteroids, icy comets are ancient objects left over from the formation of the solar system about 4.6 billion years ago. Some comets can be seen from Earth with the unaided eye. Comets typically have highly elliptical off-center orbits that swing near the Sun. When a comet is heated by the Sun, some of the ice on the comet’s surface turns into gas directly without melting. Comets were long regarded as supernatural warnings of calamity or signs of important events. </li></ul>