How new is our galaxy ?

Question

How new is Earth and our galaxy compared to the rest of the universe ?

Answer 1

The Earth is generally held to be about 4.5 billion years old.  The universe is usually believed to be between 10 and 15 billion years old (the current "best guess" is 13.7 billion years), so the Earth is much younger than the universe, between half and a third of the universe's age.

According to the Big Bang theory (which is the most widely held theory of the formation of the universe), all galaxies were formed in the same time period, though some have evolved faster than others.  This time period started perhaps 500 million years after the big bang and lasted for a few billion years.  This is because all galaxies are made up of material created in the big bang.  

Another theory, called the Steady-Sate theory, is now largely discredited.  The steady state theory suggests that as the universe expands, new galaxies form in the "gaps."  The steady state theory was a response the the fact that it *looks* like some galaxies are older than others.  The problem with this theory is that it requires the spontaneous creation of new mass in the deep space in between galaxies.  Since that space is pretty much empty it is hard to imagine how this new matter would come into being.  

This is a big part of why the big bang theory is accepted.  The big bang is the event that created all matter in the universe.  The only ways that new galaxies could form outside of that material are either if matter just spontaneously appears all the time, or if a galaxy is capable of exploding like a gigantic supernova.  If it did it would fling new material into space that could be used to form new galaxies.  The problem with this is that we've never seen any evidence that galaxies do that.

So we have to fall back to the idea that all matter comes from the big bang, which makes all galaxies roughly the same age.  The bigger ones would have formed more quickly than the smaller ones, and evolved faster, making them look older, but they really have just aged faster.  Smaller galaxies, like the Magellanic Clouds, look younger because they are smaller and so are aging more slowly.

Answer 2

The Earth and the solar system are about 4.54 billion years.

The Milky Way galaxy is about 13.2 billion years old - which is nearly as old as the Universe, which is about 13.7 billion years old.

Answer 3

The observable universe is approximately 14 billion light-years in radius; the actual items are probably a little farther away having moving since emitting the light we're seeing now.  It could be a little more or a little less but 14 billion years is a good guess.

According to radioisotope measurements, the Earth appears to be about 4.5 billion years ago.  Again, there may be a little error in either direction.

The sun is probably 6 billion years old with the galaxy age probably around 8 - 10 billion years.  This is based on the rate of planet formation as well as the fact that the metallicity of the sun suggests at least two previous generations of stars going supernova.

Answer 4

Great Galaxies! It is an infant compared to most of the others out there.

Answer 5

it depends how far away from the epicentre of the BigBang which way we are expanding in respect of other galaxis that we can see needless to say we must be traveling in virtualy the same direction! because we cant see galaxis expanding away from us going in the opposite direction. its estimated up to now, that the universe is 14 billion yrs old and our planet is 250 million yrs old. our solar system was created within the milkyway thus if it took 14 billion yrs less 250 million yrs for earth to exist given that jupiter satern ect which are much bigger than earth and comrise mostly of gas but may have solid and maulten cores as large or larger than earth then i would guess that the rest of the solar system formed over a period of say somewhere between 500 million  to 1 billion years ago then id suggest thec same time frame for our galaxy 1.5 bilion x 2 = 3 billion yrs ago maybe less if most of the fomation happened similtaniously to a large part altho earth and mars ect the smaller planets were built from resedue dust and rock, gas ect from the fomation of the bigger boys all clumped together and brocken up again by the blast of the sun id say our galaxy is fairly young not quite middle aged but pretty grown up and well established in the galaxy comunity