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Continents Earth's total landmass is exceeded by a factor of almost three to one by the surface of the oceans. Still, the major land divisions- the continents- are what give the shape and physical identity to the planet. The seven Continents represent some 57 million square miles in area, portioned unequally among them. They range in size from Asia, the largest, to Australia, the smallest. Although Europe and Asia form one large landmass, they are usually regarded as two Continents, due mainly to the cultural differences between their peoples ..read more

Formation of Earth Spiral galaxy, as seen by Hubble telescope, about ten million light-years form Earth.     For as long as human beings have observed and reflected on the natural world that they inhabit, they have told stories about the formation of Earth. Creation narratives occur in just about every system of belief. They may involve the actions of primeval deities, abstract powers, or in our modern scientific worldwide physical objects and the forced that govern their interactions.     There is also a human urge to want to date the beginning of the world as we know it.     In the ea ..read more

Terrestrial Planets  The first four planets nearest the sun are known as terrestrial planets because of the earth like characteristics, especially rocky composition. But each of the four terrestrial planets - Mercury, Venus, Earth, Mars - has distinctive features that set it apart from it's neighbors in the solar system.   Mercury, closest planet to the sun, orbits the sun in only 88 Earth days, but it revolves on it's axis so slowly that one Mercurian day lasts 59 Earth days. It has a large iron core, suggesting that it lost most of it's surface in an ancient collision. Mercury app ..read more

The Sun Sunrise, Magdalena Island, Baja California, Mexico. The sun, the star closest to Earth, anchors our solar system. It seems immense to us, but compared with other stars, it is only average in size. For example, Alpha Orionis in the constellation Orion, commonly known as Betelgeuse, is almost 400 times bigger than- and 10,000 time brighter than- the sun. Still, if the sun were hollow, a hundred Earth's could fit inside.    Like all stars, the sun is a ball of hydrogen gas that radiates heat and light. It generates power by nuclear fusion: Atoms are rammed together, producing nuclear ..read more

Expanding Universe As galaxies race away from each other, they move not true but with space, for space itself is expanding. The image often used is a loaf of raisin bread. As the dough rises, the raisins(representing objects in space, such as galaxies) move away from each other and so does the dough rest in. Expansion is property of the universe as a whole and not just Galaxies. Edwin Hubble first discovered that universe is expanding in 1929. In the decades since then, astronomers have turned their attention to the implications of this finding. When Hubble's findings, astronomers had gr ..read more

What we can observe in our sky- planet, stars, gas, dust, galaxies, meteors, asteroids and more- is a small fraction of what exists. Bright matter, the visible stuff of the universe, forms only about a sixth of it's mass. What forms the rest, and how do we know it's there? Scientists know that there must be more than meets the eye because the unseen substance has gravity and appears to be holding together the parts of universe that we can see, galaxies in particular way. Because the unseen matter does not emit radiation, scientists call ithe dark matter.  What is Black Hole? A bla ..read more

Galaxies Galaxy M31, also called Andromeda,  and two smaller Galaxies.©                          The universe contains more than 125 billion galaxies, immense aggregations of stars, gas, dust, and dark matter bound by their own gravity. Galaxies vary in size, luminosity, and mass. The largest are a million times brighter than the smallest. Galaxies take one of three primary shapes: elliptical, spiral, and irregular. Many galaxy names begin with letter M followed by a number. This naming tradition began when French astronomer Charles Joseph Messier (1730-1817) cataloged stellar bodies an ..read more