“What lies west of Westeros?” Arya stark ventured out into the wild sea to find out.
For millions of years, humans have been exploring. And as they pushed out further and further,
they began exchanging knowledge of the places they’d been to, expanding the boundaries
of the world as we knew it. Our world map was finally complete in the 1820s, with the
discovery of Antarctica. But why stop at the end of the earth? Or the moon? What’s the
farthest we could go? Well, let’s find out…. Despite all our advancements, for a very long
time, the farthest man could travel was restricted to distances on the earth. In April of 1961,
that all changed when humanity became a spacefaring species. The Russian cosmonaut, Yuri Gagarin,
was the first man in space. He blasted into orbit on a 108-minute flight high above Earth.
The Americans followed a few months later. In 1969, the Apollo 11 mission landed the
first two men on the Moon. No other statement could have truly represented the significance
of this event than that of Commander Neil Armstrong, who described it as “one small
step for man, one giant leap for mankind.” Another great feat was achieved the next year
in April 1970, when the crew of NASA's Apollo 13 swung wide around the far side of the moon
at an altitude of 158 miles, putting them 248,655 miles away from Earth. It's the farthest
our species has ever been from our home planet, but it’s certainly not the farthest that
we know about. In fact, it’s mankind’s insatiable quest
to know things far beyond what we can see with our naked eyes that’s led to so many
scientific advancements. To look at the tiniest, we developed microscopes, and to look out
beyond our world, we designed powerful telescopes. Thanks to these advancements, the edge of
our map extended far beyond our solar system. Yet, till the 1900s, we still thought that
our Milky Way galaxy was the entire universe. But, not ready to give up, humans kept exploring
in the hope that maybe there’s something beyond the Milky Way as well. At this point,
astronomers noticed that some stars were dimmer than others. “Why?” they asked themselves.
“Were they dimmer because they were smaller, or because they were farther away?” The
answer came from an astronomer named Henrietta Swan Leavitt. Leavitt had studied thousands
of Variable stars; stars whose brightness, as seen from the Earth, fluctuates. She found
that if certain stars, known as Cepheid variables, pulsate at the same rate, they have the same
brightness. This discovery proved to be a milestone in measuring the distance of stars
and galaxies, since it provided a yardstick to co-relate brightness to distance. Think
of it this way: if two Cepheid variables are pulsating at the same rate but one is dimmer
than the other, it would mean that the dimmer star is farther away from the brighter star.
Since we already knew the actual distances of some of these stars, scientists could now
determine the distance to other stars simply by comparing its known luminosity to its observed
brightness. Around this time, work was also going on to
install the Hooker telescope at Mount Wilson Observatory, California. This would be the
world's largest telescope from 1917 to 1949. Astronomer Edwin Hubble arrived at this observatory
in 1919. Yes, you guessed it right…the Hubble Space Telescope is named in his honor. Using
the Hooker Telescope, Hubble identified Cepheid variables in several galaxies, including the
Andromeda Nebula and Triangulum. Using Mrs. Leavitt’s findings, he calculated and found
that these bright objects far away from the Milky Way were, in fact, galaxies outside
our own. Andromeda is, in fact, the farthest object we can see with our naked eyes on a
dark, clear night. Now we knew that the Milky Way was not the boundary of the universe;
the universe extended far beyond it. To look that far out we now have telescopes in space,
just like the Hubble Space Telescope. But the Hubble Telescope is not the first space
telescope. That credit goes to the Orbiting Astronomical Observatory 2, rightly nicknamed
the Stargazer. Using these telescopes, we’ve seen stars and galaxies far away. The enormous
blue star nicknamed Icarus is the farthest individual star we’ve seen to date. Normally,
it would’ve been too faint to view, even with the largest and most powerful telescopes.
But it appears that nature wanted us to have a look at it. It was because of a quirk of
nature that the star’s feeble glow got tremendously amplified. Astronomers using NASA’s Hubble
Space Telescope were, therefore, able to pinpoint this star and set a new distance record. It’s
so far away that its light took 9 billion years to reach Earth.
The farthest galaxy observed is named EGS-zs8-1. The light from it took 13.1 billion years
to reach us. This means that what we see of this galaxy today is actually the galaxy 13.1
billion years ago, long before the earth or even our Sun came into existence. As a matter
of fact, the universe is thought to be about 13.8 billion years old, so galaxy EGS-zs8-1
is also one of the earliest galaxies to have formed in the cosmos. According to researchers
at Yale, there are probably galaxies that are even farther away.
Yet another fascinating aspect of the universe is that its size is not fixed. Instead, it’s
always expanding. And the farther an object is from us, the faster it’s moving away
from us. So, by the time light from a faraway galaxy reaches us, it’s actually moved away.
A galaxy like the EGS-zs8-1, (which really needs a nickname or something shorter), when
it emitted its light, was 13.8 billion light-years away from us, and it has been constantly moving
away since then. According to some complex calculations, that galaxy is about 32 billion
light-years away from us now, while the star, Icarus, is 14.4 billion light-years away.
At this time, the observable universe, meaning the area that can be observed from Earth or
its space-based telescopes, is 93 billion light-years in diameter.
The expanding universe theory also means that there’s a point in the universe where things
are moving away from us at a speed faster than the speed of light; a point beyond which,
given our current scientific knowledge and technology, we can’t look into. This is
a place from where light can never reach us. This means no one really knows what lies farthest
from us, or how big our universe really is. Some say that the universe is edgeless, while
others believe in a multiverse hypothesis. To be honest, I don’t know which of these
two is true or if any of these is true, and scientists also can’t know for sure. But
we’re still inquisitive, just like our seafaring ancestors were. And if time has taught us
anything, we can be sure that one day in the future, we’ll look far beyond what we can
see today. Okay, now that we’ve talked a lot about
huge astronomical distances, it would only be normal for you to be wondering: what’s
the farthest that any of the objects we keep hurling into space have reached so far? Well,
here’s the answer: The space probe Voyager 1, launched by NASA in September 1977, is
the manmade object that has traveled the farthest and is still continuing its journey. As of
June 3, 2019, in a period of over 41 years, it’s traveled a distance of 13.5 billion
miles and receives routine commands to transmit data to Earth. Apart from the various scientific
equipment it carries to conduct its research and communicate with Earth, the probe also
carries a gold-plated audio-visual disc to initiate communication with intelligent life
forms from other planetary systems; or to at least make them know that we exist. The
disc carries photos of the Earth and its lifeforms, a range of scientific information,
spoken greetings from people such as the Secretary-General of the United Nations and the President of
the United States, and a medley, "Sounds of Earth," that includes the sounds of whales,
a baby crying, waves breaking on a shore, and a collection of music. I sure hope they
like Chuck Berry! Wait a minute -- who doesn’t like Johnny B. Goode?
Do you think intelligent life form exist in the universe? Will they be able to find the
probe and understand the content of the golden disk?
Let me know down in the comments! If you learned something new today, then give this video
a like and share it with a friend. But – hey! – don’t go away many light-years
just yet! We have over 2,000 cool videos for you to check out. All you have to do is pick
the left or right video, click on it, and enjoy! Stay on the Bright Side of life!