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Yet, in
astronomical terms it is not far at all. Although Voyager 1 has gone past the
orbits of the outer planets of our solar system, it remains within the gravitational
realm of the Solar System. A region of Space, known as the Oort Cloud, is
considered to mark the edge of the Solar System’s gravitational influence. This
vast “cloud” is where many of the comets that we see are thought to originate.
Voyager 1 is not expected to reach this “cloud” for another few centuries and
then remain within the cloud for perhaps thousands of years.
When
Voyager 1 was launched we had not yet confirmed the existence of any planets
outside the Solar System. It was not until 15 years later (in 1992) that the
first exoplanet (planet outside the Solar System) was confirmed – and that
planet was 2,300 light-years from Earth. Now, over 6,000 exoplanets have been
confirmed to exist, with less than 4% of these likely to be Earth-like.
However, current estimates put the number of Earth-like exoplanets in our
galaxy somewhere in the range from 300 million to 40 billion.
But,
contacting any life living on such exoplanets is highly unlikely.
The
nearest known Earth-like exoplanet is Proxima b, circling the star Proxima
Centauri, part of a triple star system in the constellation Centaurus. Proxima
Centauri is 4.25 light-years from us, making it the nearest star to our own
star – the Sun.
That
doesn’t sound too far, does it – only a bit over 4 light years away.
However,
do the mathematics. If Voyager 1 headed directly to Proxima Centauri, then it
would arrive there in approximately 74,500 years – 74,452 years more than it
has already travelled.
So, don’t
keep watching your phone for updates on its arrival.
Now,
consider this. Suppose Proxima b does have intelligent life living there.
Suppose further, that those Proximians also launched a space probe, with the
same technology we had, on the same day we did – 48 years ago. Then, it will be
another 37,250 years before the two probes pass by each other in Deep Space.
Here’s yet
another thought experiment. Suppose that a space probe emanating from Proxima b
were to arrive on our planet Earth tomorrow. Then, that probe would have been
launched 74,500 years ago. Can you recollect the state of the world all those
years ago?
74,500
years ago we were sharing the planet with another member of the genus Homo –
Homo neanderthalensis. Homo sapiens (as we came to be called) had left Africa, was
about to arrive in Australia, and it was to be several thousand years before
the Americas or the islands of the Pacific were settled. We had invented stone
tools and were leaving our marks in forms of artwork on cave walls.
All those
years ago we certainly had not invented the technology required to build a
machine like Voyager 1 and be able to send it off into space.
This
leaves us with two big questions.
Question
1: Are we ever likely to reach the stars?
Question
2: Are inhabitants from other star systems ever likely to reach us?
The answer
to both questions has to be: Not likely, or at least with a very low
probability.
That
answer leads to two more important questions.
When are
we going to realise that this is the planet we have, the only one we will ever
have available to us?
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