There are three great evidences that support the Big Bang theory:
The universe expands: Edwin Hubble observed that galaxies move away from each other at speeds proportional to the distance between them. This means that the universe is expanding. Then it is possible to think that, at some point in time, he was concentrating on one point. At that point the temperature and density would be extremely high, which is what we call ‘Big Bang’ or ‘Big Bang’.
The composition of the universe is three quarters of hydrogen and one quarter of helium, the two lightest elements: Both constitute 98% of the total mass of the universe. The rest of the periodic table represents approximately 2% of the total mass. All those ‘heavy’ atoms were born in the stellar nuclei. The quantities observed in the universe coincide with those that would be expected if the universe had cooled sufficiently in the three minutes following the Big Bang. That is, approximately three minutes after the initial moment, the temperature would have dropped enough to stop any nuclear reaction, leaving a universe with the observed amounts of hydrogen and helium.
Temperature and background radiation: The universe was born in an indescribably hot state and has been cooling. It was possible to measure an estimated current temperature of 2.8 Kelvin, very close to absolute zero. It was also possible to measure the emission of the Milky Way, detecting a signal, which could not be eliminated. This noise or persistent signal throughout the universe is the "echo" of the beginning of time.
These are the three main evidences that support the Big Bang Theory.
The redshift<span> of distant </span>galaxies<span> means that the Universe is probably </span>expanding. If we then go back far enough in time, everything must have been squashed together into a tiny dot and the rapid eruption from this tiny dot was the Big Bang. Another piece of evidence could be that because light takes a long time to travel across the Universe, when we look at very distant galaxies or stars we are also looking back in time. This shows us that galaxies a long time ago were quite different from those today, showing that the Universe has changed. This fits better with the Big Bang theory than the Steady State theory
the time it take for a planet to rotate on its axis makes up its day so if it were slower the day would be longer like earth, it take about 24 hours to make one full rotation.
Now for a year the distance from its star is the largest factor, because the further out the longer it takes to revolve around it, thus making a longer year.
