ABY.G | You ‘Oort-a’ See This |

ABY.G | You ‘Oort-a’ See This!

If the Kuiper Belt is a mystery, and Planet X is a cipher, then the Oort Cloud is an enigma.

We have no concrete knowledge of the Oort Cloud. Zero. Zip. Bubkes. Everything we think we know about the Oort Cloud is hypothetical. Scientists use computer simulations, including planetary orbits, the paths of known comets, and what we currently believe about how our solar system was formed.

This is the farthest point of the Solar System — the place where the sun’s gravitational influence ends. The inner edge of the Oort Cloud begin at between 2,000 and 5,000 AU from the Sun. Remember, one Astronomical Unit = 93 million miles. The cloud itself stretches out 10,000 or even 100,000 AU from the Sun — that’s one-quarter to halfway between the Sun and our nearest neighboring star. We think that the Oort Cloud may contain more than two trillion icy objects that are bigger than a kilometer.

Also, the shape of the Oort Cloud makes it different from the parts of the solar system we’ve studied so far. Instead of what is essentially a flat disk, the Oort Cloud is spherically shaped and consists of an outer cloud and a torus (doughnut-shaped) inner cloud.

This area of space was named after Dutch astronomer Jan Oort, who first theorized its existence in 1950. Oort thought that comets with very long orbits must come from an area about one light-year from the sun. Besides predicting the existence of this area, Oort discovered “dark matter,” the invisible substance that we think makes up more than 90% of the Universe. He also demonstrated that our Solar System, instead of being at the center of the Milky Way Galaxy, is along one of the arms, and that the entire Galaxy rotates from a central point. That was when he was still in his 20’s!

Some comets also come from the Oort cloud. Since they have so far to travel, these are known as “long period comets.” When these comets get closer to the sun, their surface ices vaporize, which produces an atmosphere known as a coma. They also often have two tails (one made of dust, one of gas) that can be hundreds or even millions of miles long. This atmosphere collapses when the comet’s orbit carries it far enough away from the Sun.

One of the most interesting discoveries so far in the Oort Cloud is the minor planet Sedna. Being named after the Inuit goddess of the sea, who lives in the depths of the Arctic Ocean, is appropriate for this cold and distant world. Found in 2003 by the same team that discovered Eris, Sedna is estimated to be between 800 and 1100 miles in diameter, which makes it only 75% the size of Pluto. At its closest point to the sun, it is at 76 AU, and it never gets warmer than -400°F. It makes one full rotation every 10 hours, and follows an elliptical orbit instead of a round one. It takes over 10,000 years to go around the Sun once. Although we don’t know what the surface of Sedna is like, it has nitrogen, methane, and water ice, and has a reddish color, much like Mars.

There is certainly a lot left to learn about our Solar System, and we have many different kind of tools at our disposal to help us. Let’s take a look at a couple of them in the next lesson.

Curriculum Reference Links

Earth and Space / Building Blocks/ 1: Students should be able to describe the relationships between various celestial objects including moons, asteroids, comets, planets, stars, solar systems, galaxies and space.
Earth and Space / Building Blocks/ 3: Students should be able to interpret data to compare the Earth with other planets and moons in the solar system, with respect to properties including mass, gravity, size, and composition.

10 Fun Facts: The Hab

1. Aquarius is the the world’s only permanent undersea research station.

2. Most missions last about two or three weeks.

3. Fabien Cousteau, grandson of Jacques Cousteau, beat his grandfather’s record month-long underwater expedition by spending 31 days on the Aquarius Reef Base in 2014.

4. The lab is used by NASA, the US Navy, and researchers and educators from around the globe for training and research.

5. The internet connection is better in the Hab than at many places above the water.

6. You have to swim underneath the facility in order to enter it.

7. Crew members are called aquanauts (NOT aquaNUTS!)

8. In 1994, a crew of scientists and divers had to evacuate Aquarius and climb up a rescue line to the surface in 15-foot seas after one of the habitat’s generators caught fire.

9. Aquarius was featured in the comic strip Sherman’s Lagoon in 2012.

10. The Hab was originally built in Texas.

10 Fun Facts: Coral

1. Reefs usually grow up on the east shore of land masses.

2. Parts of a coral reef can be harvested to make medications to treat cancers and other illnesses.

3. A coral reef isn’t a single organism; it’s actually a community of life that lives and thrives in one location.

4. Only about one percent of the world’s oceans contain coral reefs. That’s about the size of France.

5. Coral reefs are the largest biological structures on earth.

6. Corals are related to jellyfish and anemones.

7. There are over 2,500 species of corals. About 1,000 are the hard corals that build coral reefs.

8. Reefs grow where there are stronger wave patterns and currents to deliver food and nutrients.

9. The Great Barrier Reef is 500,000 years old.

10. Most coral reefs grow just about two centimeters per year.

10. Most coral reefs grow just about two centimeters per year.

10 Fun Facts: Invasive Species

1. To be considered invasive, a species must adapt to a new area easily. It must reproduce quickly. It must harm property, the economy, or the native plants and animals of the region.

2. Some invasive species are introduced accidentally, but others are brought deliberately.

3. Ship ballast water transports between 3,000 and 7,000 foreign species daily around the globe.

4. The total loss to the world economy as a result of invasive non-native species has been estimated at 5% of annual production

5. Invasive species have contributed to 40% of the animal extinctions that have occurred in the last 400 years.

6. Rodents are some of the worst invasive species.

7. There are an estimated 50,000 wild ring-necked parakeets in parks across London and southeast England.

8. Black and Norway rats annually consume stored grains and destroy other property valued over $19 billion.

9. Northern Pacific seastars reproduce very quickly. In one area where they were introduced, their population reached an estimated 12 million seastars in just two years.

10. Starlings were introduced to New York in the late 1800s, as part of an attempt to bring animals that were mentioned in Shakespeare‘s work to America.

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