Watch this video to know how does the Earth look like from Andromeda.
The speed of light is over 299 million meters per second or over 299 thousand kilometers per second. Speed of light is as well the fastest achievable speed in the universe or not really achievable in order to go at the speed of light. You would have to have no mass or no materials that you are made of meaning in order to go at the speed of light. You can't exist physically but we can get very close to the speed of light. The light speed may seem like much but taking into consideration interstellar distances. It is not that impressive and does not match our human ambitions to reach other stars fast sure. Light can in one second go around years 7.5 times but since light has its limits. Even when you're talking to a human 1 meter away you would see him 3.3 nanoseconds in the past or almost a billions of a second in the past everything you see around you is how it was not how it is now you can never see anything in the universe as it is now. But only in the past so. Let's start with familiar objects such as our own moon. It is 380,000 kilometers away on average meaning from earth. We see it 1.3 seconds in the past our sun as we see. It is eight minutes in the past from earth and mars is 14 minutes an average in the past which also means that rovers humans sent. There need an average 14 minutes to respond to a single command from earth and also means that you can never see mars live as well as anything. Since light speed is the limit for every speed including radio waves microwaves gamma rays and every other wave now.
Let's go a little further on another star
another system the closest star system is alpha centauri. It is 4.3 light years
away. It has three stars and the smallest star proxima centauri is a little
closer 4.2 light-years away from our sun meaning that it takes even light four
years to get to proxima centauri. Now there is an earth-sized planet their
orbits proxima centauri and it is likely solid so.
Let's suppose there is an alien observer there now
and if they had a big enough telescope the mirror likely has to be few thousand
kilometers in diameter to observers perfectly and the alien. Observer would see
earth for years in the past which from space the earth would look pretty much
the same. But if it was an extremely large telescope.
Let's say 25 million kilometers in diameter and
it could pinpoint every human it could see you four years in the past because
light four million. Observer is just reaching them from four years ago. This
also means that when we observe alpha centauri stars .we see them for years in
the past the same goes when observing every other star and milky way galaxy as
a whole the center of our galaxy is 25,000 light-years away. Meaning we see it
25,000 years in the past so then let's go a bit further with stars let's say a
star 2,000 light-years away that has a solid planet. There are naeli an
observer would have to have a telescope likely over hundreds of thousands of
kilometers in diameter just observed here from planet to thousand light-years
away. They would now see the Earth during the night not with bright dots that
we have today with cities since there were no artificial lights. But if they could
pinpoint every human well first. We need to have a telescope that is over 11
billion kilometers across which is comparable to the size of our solar system
with this gigantic. Telescope alien observer that far away Would be able to see romans and other ancient civilizations
may be as well spot a glimpse of a war that was going. On 2,000 years ago now
let's go even further another galaxy the closest big galaxy to ours is andromeda
which is bigger than milky way and in future will collide with our galaxy. Andromeda
is 2 million and 500 thousand light years away meaning we see it 2.5 million
years in the past so if an alien observer from Andromeda wanted to observers and its creatures
of its time the size of the telescope would need to be well fifteen trillion
kilometers in diameter or one-fourth the distance from sun to alpha centauri 15
trillion kilometers is more than a light year big it is 1.6
Light-years in length. Meaning light from one
side of a telescope to the other side of the Telescope would take 1 point 6 years how such a
telescope would operate is and not very clear but it sure would see her 2.5
million years in the past the thing Is that it still wouldn't be very different but
there would be no modernHumans at all from this point in time on earth
observers in a andromeda would see.
Australopithecus or all descendants of humans with their stone
tools and see Their way of life but it sure wouldn't look like
an advanced civilization. It is Also worth to mention that these observers would
see how the milky way. Actually looks like from a distance since we are
in the milky way. We just Barely have any idea of how our galaxy looks
like but let's push even more into the space.
Let's go to the largest spiral galaxy found - it
is 500 thousand light-years cross or about five times. The length of the milky
way the galaxy is 212 million light years away so again. Suppose an alien
observer points the telescope that can see even animals avert so the size of
this telescope would need to be over one quadrillion Kilometers across or 132 light-years across. Meaning
from one side of the mirror to the other side. It takes light 132 years to
travel to get a perspective a very big star clusters such as messier 68 is hundred
light years across which is smaller than this supposed alien telescope. So it's
Caesars and it doesn't see today's continents but rather one continent Pangaea
since that was 200 million years ago but they as well could see a blue ball and
they would think that. It's an oceanic planet but while looking at Pangaea alien observers would get to
see the first dinosaurs and many
Other organisms that are not here today. Including
ancient deserts and mountains who knows what would they discover about the
earth that we humans don't know so.
We can continue going back in time even further
but there's no point as of right now. Because the further the alien observer is
from earth the further into the past will it see earth now to get a perspective
of how big these light year. Distances are we're taking a look at voyager 1
spacecraft which is not headed for proxima centauri which is the closest star.
But if it were it would take 40,000 years to reach. It also voyager 1 is
traveling at a speed of 17 km/s or 60,000 kilometers per hour which is over 45 times faster than a shot bullet so
yeah cosmic. Distances are a lot larger than they may seem. But we should
always work towards improving the speed of our spacecraft. So we can explore
this universe and understand it a bit better.
August 10, 2017
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Outer Space
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