The world of astronomy was taken by storm when 'Oumuamua was
discovered in October 2017. I covered it extensively myself during the Space Weather
reports on the HPANWO Show, for example see: http://hpanwo-radio.blogspot.com/2017/11/programme-258-podcast-brian-clare.html.
'Oumuamua is a large solid object in space, an asteroid, but it is unique
because it is not in orbit around the sun. It is a wanderer through
interstellar space that just happened to have passed through the inner solar
system by coincidence. Its name means "leading scout" in Hawaiian. It quickly
became clear that this object was highly unusual in many other ways. Most
asteroids are round or irregular lumps coloured grey or black; this one was
very long and thin, shaped like a cigar about a thousand feet long and a
hundred wide. It was dark red in colour, possibly as a result of countless
aeons of being exposed to cosmic radiation. It was spotted by the Pan-STARRS
telescope on Hawaii and the only
photographs we have of the object are some grainy and low resolution shots
showing light streaks. This is because its closest point of approach to the
earth was nine million miles, that's about thirty-seven times as far away as
the moon; it was also unfortunately well past that point when it was first
spotted. It is travelling at over thirty miles-per-second relative to the sun,
that's well over three times the average speed of an orbiting asteroid. This is
why the astronomers knew it had to be interstellar; it was moving too fast to
be in solar orbit. NASA and other space agencies have discussed the concept of
a hypothetical mission to explore 'Oumuamua, but this will be very difficult
because of the object's speed. It is heading away from the solar system out
into deep space and is already past the orbit of the planet Jupiter. In just
four years at its current velocity it will pass the orbit of the planet Neptune
and then be officially outside the solar system. However, it's a bit more
complicated than that.
It has just been announced that 'Oumuamua is speeding up.
This should not be possible. An object cannot accelerate in space unless it
enters a gravitational field, the "slingshot effect" or if it slows down
(this is still termed "acceleration" in astronomy) due to friction
with something, like a planetary atmosphere. The only exception to this rule is
for... ahem!... something with its own propulsion system. Naturally when 'Oumuamua
first hit the news the question was tabled about whether it could be artificial.
Its shape and speed reminded many people, including me, of Arthur C Clarke's sci-fi
novel Rendezvous with Rama, which is
all about an alien spacecraft that visits the solar system and is explored by a
team of astronauts. The Breakthrough Listen programme got to work observing 'Oumuamua.
This is part of the SETI movement, see background links below. It examined the
asteroid with the high-power Green Bank radio telescope in West Virginia USA to
see if it was emitting any radio signals. The object was totally silent during
the entire duration of the study. However, now 'Oumuamua is speeding up, it
might be worth repeating the observation. It might be a spacecraft that has
been in "standby mode" previously and is now switched on. In another
of Clarke's stories, The Fountains of
Paradise, earth is visited by an unmanned (or should I say
"un-alien-ed") probe, dubbed "Starglider", from an
extraterrestrial civilization; and it behaves in a very similar manner to 'Oumuamua.
According to the media, the most likely reason 'Oumuamua is accelerating is because
it is really a comet. Comets do change speed and course at times because of the
"outgassing" process. This is where ice inside the comet melts and evaporates
creating water and steam jets that burst out through the object's surface and act
like rockets. This is what causes the "coma"; the tail of the comet
is made up of this material. Source: https://www.standard.co.uk/news/interstellar-object-oumuamua-is-unexpectedly-speeding-up-leaving-nasa-scientists-baffled-a3875736.html.
The certainty of the solution to this mystery varies depending on the media
spot; as you can see the Evening Standard
states that NASA scientists are "baffled" whereas Astronomy magazine takes a far more
conservative stance: Speeding
Interstellar Object ‘Oumuamua is a Comet, not an Asteroid, see: http://www.astronomy.com/news/2018/06/speeding-interstellar-object-oumuamua-is-a-comet-not-an-asteroid.
In that case though, why was it not identified as a comet sooner? Why is the assumption that it is a comet only
being suggested now because it is, frankly, the only explanation that does not
involve mentioning little green men? It is odd that this comet has suddenly
started outgassing now that it is heading away from the sun and is already more
distant that Jupiter. Comets usually begin this as they approach the sun; that
is why their tails are longer and brighter there. Sometimes the earth's orbit
passes through these tails and we get meteor showers. As comets leave behind the
hot vicinity of solar space, the remaining water inside them freezes and the
outgassing stops. Why did 'Oumuamua not outgas when it was closer to the sun,
lighting up the night sky on earth with its magnificent interstellar tail? I
hope Breakthrough Listen does take a second look at this most enigmatic of
objects. If it turns out that it is electromagnetically active as well as in
motion then we will have irrefutable confirmation that we are not alone.
See here for
background: https://hpanwo-tv.blogspot.com/2018/02/seti-and-ufos.html.