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The Future of Space Travel
Test Your Astronomy Knowledge
So you think you know a lot about astronomy? Take this little test and find out. Do not scroll down to the answers until you have answered all five questions.
Question #1: One of the following is NOT a type of telescope. Which one?
A. Herschelian
B. Copernican
C. Gregorian
D. Newtonian
Question #2: What would be the magnification of a refractor telescope if the main objective lens had a focal length of 1200mm and the eyepiece had a focal length of 30mm?
A. 36x
B. 400x
C. 360x
D. 40x
Question #3: Only one of the following is a type of eye piece design. Which one?
A. Monocentric
B. Planocentric
C. Egocentric
D. Orthocentric
Question #4: You cannot see the Aurora Borealis in the Southern Hemisphere. True or False?
Question #5: If you are going to take extended exposure photographs of the sky, which mount is the best one to use?
A. Transit
B. Altazimuth
C. Equatorial
D. Dobsonian
Test Answers:
Question #1: The correct answer is B, Copernican. Nicolaus Copernicus was an astronomer, but no telescope was named after him.
Question #2: The correct answer is D, 40x. You calculate the magnification of a telescope by dividing the focal length of the lens or mirror by the focal length of the eye piece.
Question #3: The correct answer is A, Monocentric. Three glass elements are cemented together to make a monocentric eye piece.
Question #4: The correct answer is true. The word "Borealis" means northern. In the southern hemisphere, Aurora Australis is visible.
Question #5: The correct answer is C, Equatorial. An equatorial has to be driven by only one axis to track stars as the earth rotates.
So how did you do on this little test? If you answered three of the five questions correctly, you beat the average. If you answered fewer than three questions correctly, perhaps you should either study or take up another hobby.
See Also:
Messenger Visits One of the Least Known Places in the Solar System ...
Astronomy28
The Planet Saturn
The planet Saturn resembles the planet Jupiter in many ways. Saturn is also a planet that has very little if any solid matter. It is believed that there is a hard rocky core, but that belief is unproven (albeit very probable) theory. Saturn, like Jupiter, is made up of gases and liquids. There is an internal heat source. We know this because Saturn radiates more energy than it receives.
Saturn rotates fast. It makes one complete revolution once every 10 or 11 hours. Saturn rotates around the sun once every 29.5 years. Because it rotates so fast, Saturn is flattened at the poles, making it an almost oblate planet.
The space probes, Pioneer 11, Mariner 11 and 12, and Voyager I and II, provide the best and most accurate information to astronomers about the planet Saturn, even though the Hubble space telescope takes very good images of Saturn. The space probes get "up close and personal," so to speak, and have provided information about Saturn that nothing else could have provided.
Wind velocity on Saturn is extreme. Wind speeds of more than 1,118 mph have been recorded. Unlike the winds on Jupiter, however, wind speeds on Saturn do not seem to be closely related to the positions of the belts and bands.
The rings around Saturn are one of the most interesting features. Really high-resolution pictures taken on the Voyager missions tell us that the rings are actually made up of hundreds of thousands of very small rings. The evidence suggests that the rings are composed of particles that are mostly ice crystals. A lot has been learned about the rings of Saturn over the last 20 or so years, but there is so much about them that is still a mystery. |
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Our Sun's Twin
Jorge Melendez of the Australian National University, and Ivan Ramirez of the University of Texas at Austin, are both astronomers from Peru. Using the Harlan J. Smith Telescope at McDonald Observatory located atop Mount Locke and Mount Fowlkes in the Davis Mountains of West Texas, they discovered the best candidate as a twin to our sun that has been found to date in November 2007. The findings by Melendez and Ramirez suggest that our sun's chemical composition is not unique, as some previously thought.
The star found by the Peruvian astronomers is in the constellation Draco, which is over 200 light years away from our solar system. HIP 56948, the star in question is more like our sun than any yet seen. The star may be a billion years older than the sun.
There have been three other possible twins to our sun located, but there is a major difference in the amount of lithium they contained. These stars -- 18 Scorpius, HD 98618, and HIP 100963 -- have all been contenders, but they all contain several times more lithium than our sun. This difference has led astronomers to believe that our sun was possibly unique because of its low amount of lithium. Now, it seems, maybe our sun is not so unique after all.
The search for solar twins to our sun is important because astronomers use our sun as a baseline for a variety of astronomical studies, and studying our own sun is very difficult because it is too close and too bright.
The discovery of HIP 56948 by Melendez and Ramirez lays to rest the belief that our sun is somehow completely unique and that the uniqueness is what allowed life to spring up and thrive and raises the possibility (no, probability) that life exists in other places in the universe. Maybe we aren't alone.
Related Topics: Astronomy for Kids,
The Planet Mercury, Careers in Astronomy
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