OORT CLOUD - IS THIS REALLY A CLOUD?
The Oort Cloud is not really a cloud at all but if we could ‘see’ it from a distance it
may have that appearance. It has yet to be observed, the Oort Cloud is a
spherical collection of icy objects presumed to exist in the far reaches of the
Solar System. It was first suggested by Jan Hendrik Oort in 1950, after his
observations of comets. He concluded that comets had the following things in
common:
·
Their orbits indicated that they did not
originate in interstellar space.
·
They come from all directions – there is
no single orbit.
·
Their aphelia (farthest point) tended to
group at about 50,000AU (the sun is 1AU from Earth).
Taking all of these
observations into consideration and the frequency that they occurred, Oort decided
that billions of potential comet material must exist in a spherical shell
surrounding the Solar System. Then given their distance from the sun and the
weaker gravitational pull, disturbances from objects outside the Solar System
could ‘knock’ these icy objects into plunging orbits around the Sun. This would
result in the comets we observe.
The Oort Cloud is still
generally acknowledged as the origin of the long-period comets, whereas the
short-period comets originate from the Kuiper Belt. The Oort Cloud is thought
to be an extension of the Kuiper Belt only much larger, containing billions of
objects and maybe trillions of small icy objects. Scientists believe that
during the planetary formation these objects were left-over debris. They were
caught and flung out to the edge of the Solar System by the gravitational pull
of Jupiter and Saturn, acting like a sling shot.
Two of the most famous
comets, Halley and Swift-Tuttle, possibly higher orbit comets are ones that
were pulled into shorter period orbits by the planets. Long period comets, such
as Hyakutake and Hale-Bopp can appear at any time and come from any direction,
but these two bright comets can usually be seen every 5 to 10 years.
We still have much to
learn about the Oort Cloud. To date, scientists believe this region may contain
the existence of two Oort Clouds, the inner and the outer clouds. They believe
that the objects that reside there formed closer to the sun and were scattered
to the outer regions due to gravitational effects. The last theory most
commonly accepted is that the Oort Cloud defines the outer most region of our
Solar System under the influence of the gravitational pull of our sun.
Let’s take a look – Images and a video:
My sources: Kids Astronomy, Wikipedia, Solarviews.com,
Space.com, European Space Agency, Astronomy/Cosmos, and Universe Today.
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