Frequently Asked Astronomy Questions
What power is your telescope?
What is the difference between f-ratio, focal length and focal point?
Can I see the American Flag or the Lunar Lander on the Moon?
Is Pluto a planet?
What is a Star Party?
Basically, when you get a group of amatuer astronomers together with their telescopes a good time is usually had by all. At a public Star Party it is polite to ask questions (yes,even the stupid one- the only stupid question is the one you dont ask). The only rules at a star party are no touching the scope enless you ask, red lights only, and have FUN! There three types of star parties: local, regional, and national. Local is something your area Astronomy Club may through for special events. Regional like the Mason-Dixon Star Party, where 400 amateur astonomers gathering together for a weekend. A national star party like the Nebraska Star Party where astronomers will travel across the country just to see what the Milky Way should look like!
Telescope are not really measured by power, like its cousins the microscope and binoculars. Instead the important thing is aperature (the diameter of your optics), bigger is better. The rule of thumb is 50 times per inch of aperature. For example, a 10 inch telescope is capable is of magnifying 500 times. However, that’s perfect optics, perfect weather, and the darkest skies. If you live in Maryland, two out of those three never happen. So, in practice 30 times per inch is more likely. To find your magnification take the focal length of your eyepiece and divide it into the focal length of your telescope. If you are using a 5 mm eyepiece on a telescope with the focal length of 1000 mm your magnification is 200 times. Note: Even the Hubble Telescope does not use all of its magnification. 50 times 168 inches (14ft diameter of HST)= 8400 times – The highest powered camera is only around 1600 times.
What is the difference between f-ratio, focal length and focal point?
Good Question! I think these were designed for confusion. Focal point is the actually spot your telescope brings light to a point. Focal length is the distance between the optics and the focal point. In the case of a refractor it is generally the length of the tube. For a reflector, focal length is the entire length light travels, bouncing off all those mirrors. Focal ratio or f/ is the ratio between the focal length an the aperature. A 10 inch f/4.5 scope has focal length of 45 inches of roughly 1125 mm.
Can I see the American Flag or the Lunar Lander on the Moon?
The short answer is NO! The lunar module is about the size of two phone booths the magnification required to see these from 250,000 miles away would some around one million times. The most powerful telescope on the planet if it could look at the Moon can only image something 300 yards across. That is a far cry from two phone booths not to mention a flagpole as viewed from the top down.
It really depends who you ask, but according IAU (International Astronomical Union)- NO. But if you are still not convinced, here is a brief history lesson.
In 1834, if you look in text books of that era we have 11 planets (Neptune and Pluto were not discovered yet). On Jan. 1, 1801, there was a “planet” discovered between the orbits of Mars and Jupiter, later it named Ceres. Four months later, three more “planets” were discovered with roughly the same orbits. What astronomers discovered was the Asteroid Belt, in order to save face the pros demoted them to minor planets.
Basically the same thing is going on with Pluto. However instead of four months between discoveries its 80+ years. If it were discovered today, it probably would be classified as a Kuiper Belt Object (KBO). Currently (as of July 2008), there are approximately 1000 known objects. Estimated projections predict millions of objects, the Kuiper Belt is quickly becoming the largest structure in the Solar System.
For more information on history of asteroids visit The Applied Physics Lab’s Near Earth Asteroid Rendezvous (NEAR) project.