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Ten Random Astromony Questions

January 21, 2010 Leave a comment

1. What are the steps in the scientific method?

The scientific method is the method used to explore observations and answer questions within the scientific community. It is a step by step process that has evolved since the earliest days of the analysis of observation. The first step in the scientific method is to ask a question about something that is observed. After a question is proposed, one must research in order to find the most appropriate process to find the answer and to ensure that mistakes that have been documented in the past are not repeated. Next, the researcher must propose a hypothesis, which is an educated guess constructed as an if-then statement, which can be easily measured and interpreted. Then the researcher must plan and implement a scientific experiment in order to test the hypothesis. After the experiment is concluded, the researcher must interpret the measurements and draw conclusions which either support or oppose the hypothesis. If the hypothesis is proven false, a new hypothesis must be formulated and the process continues from there; however, if the hypothesis is supported and methods are repeatable, the researcher must communicate his results to be verified by the rest of the scientific community.

http://www.sciencebuddies.org/science-fair-projects/project_scientific_method.shtml

2.   How is a light year defined?

A light year a unit a measure used in astronomy due to the vast distances between astronomical bodies. Our Sun, for example, is approximately 150 million km away from the Earth. It is impractical to define such large distances by miles or kilometers, so scientists developed several different units of measure for astronomy. One such measure is the light year. It is defined as the distance that light travels in one year. Light travels at 300,000 kilometers per second. So in a year, light travels 9,460,800,000,000 kilometers. What this means for astronomers is that if a star is 100 light years away, the light that we are seeing from the star represents what the star looked like 100 years ago not what it looks like at the present time.

http://www.howstuffworks.com/question94.htm

3.  Describe what happens during the two kinds of eclipses?

There are two categories of eclipses. These are solar and lunar. In a solar eclipse the moon passes directly between the Sun and the Earth obstructing the path of the Sun’s light to the Earth. Whether or not the viewer sees a partial or total eclipse depends on what part of the moon’s shadow falls on the Earth. The total eclipse in only visible in the umbra and this part of the shadow is very small on the Earth. A partial eclipse is observable in the penumbral shadow which covers a larger part of the Earth’s surface. The second eclipse category is called a lunar eclipse. This phenomenon occurs when the Earth passes between the Sun and the Moon during a full moon and the moon passes with in the umbral shadow of the Earth.

http://www.mreclipse.com/Special/SEprimer.html

http://www.mreclipse.com/Special/LEprimer.html

4. What is surface gravity?

Surface gravity is defined as the gravitational acceleration on the surface of an astronomical object such as a planet or a star. It is measured in units of acceleration, which is meters per second squared. Each astronomical body has a unique surface gravity which is determined by the product of the gravitational constant, G, and the mass of the object divided by radius of the object squared. The relative surface gravity of the Earth is 9.81 m/s squared. This means, that the gravitational pull of Earth exerts enough force to pull every object that is caught in its gravitational field toward itself at a speed of 9.81 m/s squared. Further, two objects that are accelerating toward the Earth’s surface will do so at this speed barring any outside interference. This outside interference is measured by multiplying the gravitational constant or G. For example, an F-16 fighter can withstand up to nine Gs. Within the equation, the number nine becomes the coefficient to measure the final modified surface gravity when taking into account the outside interference.

5. What is the difference between reflecting and refracting telescopes?

Every optic telescope falls in to one of two classifications, either refracting or reflecting. The telescopes are classified according to the method that they use to focus the image into the viewing device.  A refracting telescope uses lenses to gather and focus light, while a reflecting telescope uses a mirror. The refractor telescope gathers a greater amount of light into the lens than is possible to gather with the naked eye. This presents the observer with a brighter, clearer, and magnified image of the object being observed. This is accomplished by focusing the parallel light onto a focal point while the peripheral light is focused onto a focal plane. A reflecting telescope uses a combination of curved mirrors that reflect light and form an image into a viewing device. A curved primary mirror is the basic optical element and creates an image at the focal plane. A viewing device such as film or a digital sensor may be located at the focal plane to record the image or an eyepiece might be present for viewing the image. The mirror in most modern telescopes is composed of solid glass that has been ground into a parabolic or spherical shape with a thin layer of aluminum deposited on the front which provides a highly reflective metal surface to reflect the images. The light from the image enters the end of the tube and reflects off the primary mirror, to the secondary mirror, and finally to the viewing device. Reflectors are not only useful for measuring visible light, but they can also detect shorter and longer wavelengths (e.g. ultraviolet and infrared light).

http://abyss.uoregon.edu/~js/glossary/reflecting_telescope.html

6. What are the Oort cloud and Kuiper Belt?

The Kuiper belt is a disk shaped region of icy debris about 30-50 AU from the Sun, which is outside the orbit of Neptune. It is similar in organization to the asteroid belt although it is far larger being 20 times as wide and 20-200 times as massive. Although similar in organization, the make up of the individual bodies is markedly different. The asteroid belt is similar to terrestrial planets being made mostly of rock and metal while the Kuiper Belt Objects (KBOs) share a similarity with the Jovian planets being made principally of frozen volatiles such as methane, ammonia, and water. The Kuiper belt is also the home of the dwarf planets Pluto, Haumea, and Makemake. Another organized structure of astronomical bodies has been theorized to exist called the Oort cloud, named for Jan Oort who originally theorized its existence in 1950. Light is so scarce in the far reaches of the proposed solar system that it is extremely difficult to identify the existence the cloud. The main evidence for the belt is the passage of long-period comets that pass through the inner solar system only once. The Oort cloud is home to astronomical bodies that vary in size from 50km to the size of Pluto. It has been theorized that there might be larger bodies within the Oort cloud as well, but no conclusive proof has yet been presented to confirm or deny this presumption.

http://solarsystem.nasa.gov/planets/profile.cfm?Object=OortCloud

7. What are the advantages of a telescope in space?

The main advantage of using a telescope that is based in space rather than on Earth is simply that the space telescope does not have to compete with the Earth’s atmosphere for light. The Earth’s atmosphere can distort the imaging ability of the earthbound telescope. It also blocks x-ray and infrared light so that those spectrums cannot be studied from Earth. Also, a telescope based in space does not have to deal with light pollution as do observatories on Earth.

8. What is a dwarf planet?

A dwarf planed it s a celestial body that is in orbit around the Sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape, has not cleared the neighborhood around its orbit, and is not a satellite. The classification was created for objects that are not quite large enough to be considered planets, but are larger than asteroids. There are currently five celestial bodies that are defined as dwarf planets.

9. What is meant by the resolution of a telescope?

The resolution of a telescope is defined as how clearly a telescope is able to view objects. The higher resolution yields a better ability to make out fine details in the celestial bodies being observed. Resolution is based highly on the quality of the optical components within the telescope, but the aperture, the hole that the light enters the telescope, of the telescope is also critical when dealing with resolution. For this reason, astronomers build bigger telescopes to allow more light in the aperture, increase the resolution, and create a finer more precise picture.

10. What is the difference between the geocentric and heliocentric model of the solar system?

The difference between the geocentric and heliocentric models of the universe hinges on Earth’s role in universal organization. The earliest thinkers believed that the Earth was the center of the universe and all things revolved around it, which was the central idea in the geocentric model of universal organization. This was refuted in 1530 when Copernicus presented a mathematical model in his book De Revolutionibus. Copernicus’ theory upset the religious order of the time so his work was refuted and suppressed, but eventually, with the invention of the telescope, Copernicus’ theory of the heliocentric  model of universal organization became provable scientific fact.

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The Kupier Belt and the Oort Cloud

October 29, 2009 Leave a comment

As the science of optics continues to advance, the scientific community is able to probe further and further into the universe. They are able to identify and classify celestial bodies that have previously been undetectable. One such organization of celestial bodies is the Kuiper belt.

Kuiper Belt

The Kuiper belt is a disk shaped region of icy debris about 30-50 AU from the Sun, which is outside the orbit of Neptune. It is similar in organization to the asteroid belt although it is far larger being 20 times as wide and 20-200 times as massive. Although similar in organization, the make up of the individual bodies is markedly different. The asteroid belt is similar to terrestrial planets being made mostly of rock and metal while the Kuiper Belt Objects (KBOs) share a similarity with the Jovian planets being made principally of frozen volatiles such as methane, ammonia, and water. The Kuiper belt is also the home of the dwarf planets Pluto, Haumea, and Makemake.

The existence of objects beyond the Neptunian orbit was first theorized in 1930 by Frederick C. Leonard soon after Pluto’s discovery. The theory continued to evolve over the next 60 years. Ironically, Gerald Kuiper, influential astronomer of the 20th century, whom the belt is named for, believed that such a disc of astronomical bodies may have formed early in the Solar System’s early evolution, but that the belt did not exist today. In 1992, an object in the belt was discovered by astronomer David Jewett. Six months later, Jewett’s team discovered a second trans-Neptunian object (TNO). The number of identified KBOs has increased to over a thousand and more than 70,000 KBOs are believed to exist within the belt.

Oort Cloud

The Kuiper belt is not the only believed source of TNOs. Another organized structure of astronomical bodies has been theorized to exist called the Oort cloud, named for Jan Oort who originally theorized its existence in 1950. Light is so scarce in the far reaches of the proposed solar system that it is extremely difficult to identify the existence the cloud. The main evidence for the belt is the passage of long-period comets that pass through the inner solar system only once. The Oort cloud is home to astronomical bodies that vary in size from 50km to the size of Pluto. It has been theorized that several there might be larger bodies within the Oort cloud as well.

Celestial bodies within the Kuiper belt and the Oort cloud continue to spur on the study of deep space. As it stands now, no spacecraft has left the bounds of the known solar system, but that is slated to change in 2015. The unmanned craft, New Horizons, will arrive at Pluto in 2015 and begin the exploration of the dwarf planet and its moons as well as exploring further into the Kuiper belt. With the exciting advances in optics and long range study devices such as New Horizons, the understanding of the outlying areas of the solar system will continue to bring further insight into Earth’s small corner of the galaxy and the universe as a whole.

New Horizons Mission

References

http://solarsystem.nasa.gov/planets/profile.cfm?Object=KBOs

http://solarsystem.nasa.gov/planets/profile.cfm?Object=OortCloud

http://www.nasa.gov/mission_pages/newhorizons/main/index.html