Wednesday, July 2, 2014


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,,, European Space Agency, Astronomy/Cosmos, and Universe Today.

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