Big Bang Theory , currently accepted explanation of the beginning of the universe.
A cosmic reaction, called the big bang, occurred about 13.7 billion years ago, and the universe has since been expanding and cooling
Once extremely compact, dense, and hot. This would have released radiation, and that radiation should still be visible today.
American astronomer Edwin Hubble provided some of the greatest supporting evidence for the theory with his 1929 discovery that the light of distant galaxies was universally shifted toward the red end of the spectrum.
Proved that the galaxies were moving away from each other.
Another cause of red shift is the expansion of the universe , which explains the observation that the red shifts of distant galaxies , quasars , and intergalactic gas clouds increase in proportion to their distance from the earth. This mechanism is a key feature of the Big Bang model of physical cosmology
The radiation was found in the 1960s, by complete serendipity, by a researcher at Bell labs trying to determine the source of interference in trans-Atlantic telecommunications. As it turned out, a strikingly uniform source of microwaves was coming from everywhere in the sky - and it had a corresponding temperature of 2.7 Kelvin. This was the discovery that vindicated the Big Bang theory. Still, it's hardly the only one.
There is nuclear evidence in the elements (hydrogen, helium, carbon, etc.)
Radiation Map of the Universe Astronomy probe 5-yr mission
All galaxies began forming at about the same time approximately 13.7 billion years ago.
They formed from huge gas clouds larger than the resulting galaxy. The clouds began collapsing because their internal gravity was strong enough to overcome the pressure in the cloud.
If the gas cloud was slowly rotating, then the collapsing gas cloud formed most of its stars before the cloud could flatten into a disk. The result was an elliptical galaxy .
If the gas cloud was rotating faster, then the collapsing gas cloud formed a disk before most of the stars were made. The result was a spiral galaxy .
Irregular galaxies are clouds/stars that began to form in the swirling disk of gas and the system began to be recognizable as a galaxy. These early galaxies are very rich in gas, rather irregular in shape and speckled with extremely luminous blue stars.
Out of this World!
Galaxy Formation Out of this World! Out of this World!
Out of this World! 5. Also, in the universe, there are billions and billions of stars .
Neutron stars pack roughly the mass of our Sun into a region the size of a city. Here's a comparison with Chicago:
Out of this World! C. White dwarfs and eventually black dwarfs (what the least massive stars will become, like our sun)
Out of this World! 12. The more massive stars explode before they become neutron stars or black holes. This incredible sight is referred to as a supernova . This is a photograph of Supernova 1987 a, one of the only ever witnessed.
Out of this World! 13. The second closest star to us is called Alpha Centauri , which is 4.3 light years away. Although it appears as one bright light, it is actually three separate bodies! Here is how the three stars that make up Alpha Centauri compare to the sun.
Out of this World! Many stars are like this… when there are more than one “body” that we see as one light, the stars are called companions (because they go together). The Chandra image shows Mira A (right), a highly evolved red giant star, and Mira B (left), a white dwarf.
Out of this World! Two stars like this are called binary stars , the prefix bi- means “two” (like a bicycle). Mira (shown here) is an example of such a star system. The companion star to Mira is referred to as Omicron Ceti A.
Because the universe is so big, scientists have to use a measurement of distance known as a light year , which is how far light can travel in one earth year.
Interesting Facts About Light Years: • It takes 8.3 minutes for light to travel from the Sun to the Earth (a distance of 1.58 × 10 -5 light years). • The most distant space probe, Voyager 1, was 13 light hours away from Earth in September 2004. It took the probe 27 years to cover that distance. • The center of our galaxy, the Milky Way, is about 26,000 light years away. The Galaxy is about 100,000 light years across. • The Triangulum Galaxy (M33), at a bit under 2.6 million light years away, is the most distant object visible to the naked eye.
Out of this World! Unfortunately, we can’t travel that fast (yet?), but if we could, Einstein thinks several changes would happen to us: a. We would become more massive. b. We would shrink in length. c. Time would pass slower . This is outlined in his Theory of Relativity , which explains how mass, distance, speed, and time are interrelated - a strange concept to think about! See an example of what Einstein means… http://www.pbs.org/wgbh/nova/einstein/hotsciencetwin/index.html
Out of this World! 15. People have studied the stars for thousands of years. In doing so, they have identified groups of stars that appear to form pictures in the sky. These are known as constellations . There are 88 identified constellations in all - most of which have some sort of story or myth associated with it.
Out of this World! 16. The North Star is always visible from our viewing point on earth; it is also known as Polaris (like the shopping mall).
Out of this World! 17. One of the most influential instruments (if not the most influential) in discovering what we know about the universe is the Hubble Telescope.