Visitors From Outer Space

Comet

Comet
Comet

Unpredictable Shining Objects


In the past, people looked with awe and amazement at the shining objects that appeared unpredictably in the sky. When looking at a comet,They imagined a sword blazing across the sky, a sign of war and death: For others, it was a woman with her hair flowing behind her, a sign that the gods were displeased; however, in the present everybody knows what a comet is.

In modern days, scientists have discovered that a comet is composed of an icy nucleus, which is no bigger than a few kilometers. The nucleus contains tiny bits of ice and frozen gases with embedded tiny particles of rock and dust. The nucleus might contain a small rocky core. Comets are leftovers from the interstellar particles that formed the solar system 4.6 billion years ago. It is theorized that comets might have brought water and organic compounds to the inner solar system.

Short-period comets originate in the kuiper belt which is a disk-like belt of icy bodies in the trans-neptunian region. Comets from this region are pushed from time to time into orbits which bring them closer to the Sun. Their orbital periods are less than 200 years, and occasionally their appearances can be predicted. One of the best known short period comets, with an orbital period of 76 years, is comet Halley which last appeared in 1986, and will appear again in 2061.

Long period comets inhabit a region known as the Oort cloud, which lies at approximately 150,000 astronomical units (AU) from the sun. Comets from this region are less predictable and it can take as long as 30 million years before an Oort cloud comet completes one orbit around the Sun.

Glowing Tail MIllions of MIles Long

In the outer solar system, a comet remains in frozen state; however, when the comet comes into the inner solar system, it encounters the rays from the Sun which causes the nucleus of ice to change its frozen state into a gas in a process known as sublimation (the solid ice turns into a gas without becoming a liquid), A sudden flare-up of gas and dust are thrown in every direction, forming a luminous halo around the nucleus known as coma.

The solar wind causes the gas and dust particles in the coma to spread out each of them forming two distinct tails of glowing light, and pointing in slightly opposite directions. Their tails can spread for millions of miles across the night sky.


Stardust

Stardust
Stardust

Stardust Mission

Many comets are named after their discoverers, for instance, comet Shoemaker-Levy 9 was named after Eugene and Caroline Shoemaker and David Levy. Other comets have been named after the spacecraft that have identified them, including LINEAR; SOHO; WISE, etc.

In 2004, the stardust mission from NASA successfully flew within 236 km (147 miles) from the nucleus of comet Wild 2. Samples of gas and dust were collcted. In 2009, scientists announced that the amino acid glycine was found in the particles of gas and dust collected by stardust mission.


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Comments 6 comments

somethgblue profile image

somethgblue 4 years ago from Shelbyville, Tennessee

What is the Van Ryan asteroid belt and why was NASA so concerned about getting through it to reach the Moon?

Great Hub BTW, very informative!


unvrso profile image

unvrso 4 years ago from Mexico City Author

It is thought that the radiation within the Van Allen Belt could have a strong effect on the instruments of shuttles and bodies of astronauts http://en.wikipedia.or/wiki/Moon_landing_conspirac...


somethgblue profile image

somethgblue 4 years ago from Shelbyville, Tennessee

Thanks for clearing that up for me, I knew it was called something like that.

Your a good writer, I'm a little surprised by the lack of followers and comments!

Good Hub!


unvrso profile image

unvrso 4 years ago from Mexico City Author

I find it normal. At the other site that I write at, I haven´t received but a few comments after more than a year. What interest me is the traffic that my articles can generate. I signed up for Hub Pages one year ago, but abandoned it for a while. I resumed one month ago and I think I´m doing fine. I visited your profile. I think you write interesting articles. I read; 2012 Apocalyptic Cataclysm, Conscious Ascension Or Both.


somethgblue profile image

somethgblue 4 years ago from Shelbyville, Tennessee

I have found some key elements for attracting traffic includes, mentioning the title in the opening paragraph, once in the article and in the closing paragraph (google likes this).

Selecting tags is important as well as the title and posting the article on at least four social sites, Facebook, StumbleUpon, RedGage and Reddit to name a few.

The Hub article http://hubpages.com/literature/Hollow-Earth-Fact-o... has graced page one of Google for three straight weeks, but isn't even close to the most readers (viewers).

My article on the illegal criminalization of marijuana has gotten over 2,000 viewers in a little over a month, mostly due to the topic.

Another great way to get viewers is to hop some hubs and leave engaging commnets.


unvrso profile image

unvrso 4 years ago from Mexico City Author

Thanks! somethgblue. I have posted at StumbleUpon, Reddit, but since I´m still learning, I don´t have any idea on how it really works. I always add tags to my articles, and just one mention to the title. I´m going to try hop. I found your suggestions really helpful. Hope it helps whoever happens to read them.

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