The universe began with the Big Bang around 13.6 billion years ago. The Big Bang was a rapid expansion of the universe from a tiny single point. This hot expansion has continued since then, resulting in the expansion of the universe in every direction.Know More
At the time of the Big Bang, the universe and all of its matter was concentrated in a single point. As the Big Bang started, this matter was heated to very high temperatures and expanded rapidly.
Several scientific observations have convinced astronomers that the Big Bang theory is correct. One of the strongest pieces of evidence is called the cosmic microwave background, or CMBR. This is the remaining heat from the Big Bang that can be seen in all directions when looking into the universe. As the universe has expanded, the initially hot material has cooled, so that it now emits light as microwaves.
By looking at distant galaxies and stars, scientists have also discovered that everything seems to be moving away from the Earth. The further away a galaxy is, the faster it appears to be moving. This shows that the universe is still expanding, although there is debate as to whether this expansion will continue forever.Learn More
Although the ultimate fate of the universe is a largely debated topic, according to the University of Tennessee, in an open universe the universe will continue to expand forever. This is due to insufficient mass to cause the expansion to stop.Full Answer >
The solar system is a system in the universe that is comprised of the Sun, eight official planets, three dwarf planets and approximately 130 satellites of the planets, according to Nine Planets. Besides these bodies, the solar system also has numerous comets and asteroids, which are smaller. On the other hand, the Milky Way is the galaxy within which the solar system falls.Full Answer >
By taking measurements of background microwave radiation, scientists have been able to establish that the average temperature of the universe is just over 2.7 degrees Kelvin. This means that the average temperature of space is just below negative 450 degrees Fahrenheit.Full Answer >
Ptolemy's model of the universe was geocentric, containing the Earth at the center with a series of circles, called deferents, moving outward from the Earth, containing the moon, Mercury, Venus, the sun, Mars, Jupiter and Saturn. Ptolemy placed fixed stars and the Primum Mobile in the spheres after Saturn.Full Answer >