Introduction
Galaxies are immense collection While individual stars may seem vast in comparison with Earth, galaxies can often contain trillions of stars and span hundreds of thousands of light years. Scientists are still unsure how galaxies are formed from the dark void of fog and gas that was the early universe.
Galaxy shapes
Galaxies come in all shapes and sizes. A third of all galaxies are spiral, spinning around like Catherine wheels. Old stars are packed tightly in their centre, while young stars emerge continuously from the gas and dust in their spiral arms. Elliptical galaxies get their name from their oval shape. They are formed from billions of old red stars and have little gas with which to create new stars. Some galaxies can't be classed as either spiral or elliptical as they have no recognizable shape. They are called irregular galaxies and are usually quite small. These galaxies are full of gas in which new stars are forming all the time.
Cosmic collisions
Galaxies are normally separated by vast, empty gulfs. However, very rarely two galaxies are travelling at millions of kilometres per hour, and the impact can be tremendous. The individual stars in a galaxy don't collide, but the vast clouds of interstellar gas and dust smash into one another, triggering a ferocious birth of new stars. The results of an impact vary. Each galaxy is held together by nothing but gravity, causing an immense battle of strength. Sometimes galaxies merge to form even larger galaxies. At other times, galaxies can be sistorted or even ripped apart by the impact.
Active galaxies
A small percentage of the galaxies known today stand out from the rest. Violent explosions occuring in their cores force out giant streams of gas. These plumes can stretch for thousands of light years. Such galaxies are called active galaxies and their energy doesn't come from the light from the stars inside them but from the heat generated by enormous black holes in their central region. Quasars are among the most powerful and most distant galaxies in the universe. Their light has taken billions of years to reach us, so they show how universe behaved near its birth.
Some important facts
1) Galaxies are also known as the island universe after a suggestion by Immanuel Kant, a German philosopher.
2) Most galaxies form when giant clouds of gas collide. If the clouds are rotating, they form a spiral galaxy. If not, they probably form an elliptical galaxy.
3) The Cartwheel Galaxy was hit by another galaxy 300 million years ago. It used to be a spiral galaxy, but a smaller galaxy, travelling very fast, smashed through its centre. The blue ring around the central region is made up of millions of new stars triggered by the impact.
Facts and figures
Nearest galaxy distance(Ly)
Sagittarius 78,000
LMC 160,000
SMC 190,000
Ursa Major 225,800
Draco 248,000
Sculptor 250,000
Carria 280,000
Sextans 290,000
Fornax 430,000
Leo II 750,000
Galaxies are immense collection While individual stars may seem vast in comparison with Earth, galaxies can often contain trillions of stars and span hundreds of thousands of light years. Scientists are still unsure how galaxies are formed from the dark void of fog and gas that was the early universe.
Galaxy shapes
Galaxies come in all shapes and sizes. A third of all galaxies are spiral, spinning around like Catherine wheels. Old stars are packed tightly in their centre, while young stars emerge continuously from the gas and dust in their spiral arms. Elliptical galaxies get their name from their oval shape. They are formed from billions of old red stars and have little gas with which to create new stars. Some galaxies can't be classed as either spiral or elliptical as they have no recognizable shape. They are called irregular galaxies and are usually quite small. These galaxies are full of gas in which new stars are forming all the time.
Cosmic collisions
Galaxies are normally separated by vast, empty gulfs. However, very rarely two galaxies are travelling at millions of kilometres per hour, and the impact can be tremendous. The individual stars in a galaxy don't collide, but the vast clouds of interstellar gas and dust smash into one another, triggering a ferocious birth of new stars. The results of an impact vary. Each galaxy is held together by nothing but gravity, causing an immense battle of strength. Sometimes galaxies merge to form even larger galaxies. At other times, galaxies can be sistorted or even ripped apart by the impact.
Active galaxies
A small percentage of the galaxies known today stand out from the rest. Violent explosions occuring in their cores force out giant streams of gas. These plumes can stretch for thousands of light years. Such galaxies are called active galaxies and their energy doesn't come from the light from the stars inside them but from the heat generated by enormous black holes in their central region. Quasars are among the most powerful and most distant galaxies in the universe. Their light has taken billions of years to reach us, so they show how universe behaved near its birth.
Some important facts
1) Galaxies are also known as the island universe after a suggestion by Immanuel Kant, a German philosopher.
2) Most galaxies form when giant clouds of gas collide. If the clouds are rotating, they form a spiral galaxy. If not, they probably form an elliptical galaxy.
3) The Cartwheel Galaxy was hit by another galaxy 300 million years ago. It used to be a spiral galaxy, but a smaller galaxy, travelling very fast, smashed through its centre. The blue ring around the central region is made up of millions of new stars triggered by the impact.
Facts and figures
Nearest galaxy distance(Ly)
Sagittarius 78,000
LMC 160,000
SMC 190,000
Ursa Major 225,800
Draco 248,000
Sculptor 250,000
Carria 280,000
Sextans 290,000
Fornax 430,000
Leo II 750,000
0 comments:
Speak up your mind
Tell us what you're thinking... !