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The Planet Mercury
Telescope Jargon
There is a language of astronomy. You need to know what the terms mean before you buy a telescope to ensure that you buy the telescope that is best suited for your needs. Some of the terms you will hear are:
1. Magnification and aperture: On the box that a telescope comes in, these two terms are represented by numbers like 6 x 30 or 8 x
50.
a. The first number represents the magnification. The number 6 means that distant objects appear to be 6 times their size when viewed through the telescope. Magnification is not as important, however, as aperture.
b. Aperture is represented by the second number and tells you the surface area of the lens or mirror of the telescope. The primary function of a telescope is to gather light. Aperture is more important than magnification in viewing celestial objects.
2. Focal length: Focal length is the distance that light travels from the telescope's lens or mirror to the focal point inside the telescope. The size of the image at the focal point will be larger the longer the focal point is.
3. Focal ratio: The term "focal ratio" is the ratio between the aperture and the focal length.
4. Refractor telescope: The refractor telescope gathers light through the use of a lens. Refraction is one of three ways in which telescopes gather light.
5. Reflector telescope: A reflector telescope gathers light through the use of a mirror.
6. Catadioptic telescope: A catadioptic telescope gathers light through the use of both lenses and mirrors.
7. Equatorial mount: An equatorial mount is a telescope mount with one axis that is parallel to the earth's axis, and points to the celestial North Pole.
8. Altazimuth Mount: An altazimuth mount is a telescope mount with two axes. It allows for movement in two directions, horizontally and vertically.
See Also:
Famous Meteorites (Cosmic Collisions) - Cosmeo
The Planet Venus
The Planet Mercury
The planet Mercury is the smallest planet in our solar system, and the one that is closest to the sun. This proximity to the sun has made it difficult to study the planet. The closest look that we have ever had was in 1974 and 1975 when the unmanned Mariner 10 was sent to map the surface of Mercury. Only about 40% to 45% of the surface was actually mapped.
Mercury resembles our moon in appearance as it is heavily cratered. There is an atmosphere of sorts on Mercury but not one that would sustain life as we know it. The atmosphere is very unstable and is made up of hydrogen, helium, oxygen, sodium, calcium and potassium.
Records of studies made of Mercury date back to 300 BC. The name "Mercury" was given to the planet by the Romans after the god Mercurius. Chinese, Korean, Japanese, and Vietnamese cultures refer to Mercury as the water star based on the Five Elements. Other cultures have called the planet by other names. The Babylonians, for example, called the planet Nabu or Nebu after the messenger to the Gods in their mythology.
The temperature on Mercury varies. The average temperature is 179° C, but the extremes are a low of -183 °C to a high of 427° C. Sunlight on Mercury is six and a half times stronger than it is on Earth.
There is evidence that water does exist on Mercury despite the extreme temperature variations. The bottoms of some of the deepest craters near the poles are never exposed to direct sunlight. Temperatures in these areas remain far lower than the global average, so it is possible for ice to exist. |
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More articles:
Self-Portrait on The Planet Mars
Basic Astronomy QUIZ: Chapter 21
History of Astronomy (IAU Commission 41)
NASA - Home
Astronomy Binoculars : Binoculars - Shop at Binoculars
Buying a Telescope
History of Astronomy
Astronomy is the oldest of all sciences. It has its roots back in the beginning of time. There is evidence of astronomy playing a large role in religious, mythological, and astrological practices of pre-history. Mankind has always looked to the heavens with wonder mixed with a healthy dose of curiosity.
In the earliest cultures, heavenly bodies were identified as gods or spirits, and these gods and spirits were thought to control such things as rain, drought, seasons, and the tides. The first astronomers are believed to have been priests or Magi. The earliest calendars were based upon the phases of the moon and the time between phases.
Western astronomy has its roots in ancient Mesopotamia astrology. The modern practice of dividing a circle into 360 degrees, of 60 minutes each, began in ancient Mesopotamia with the Sumerians.
The oldest astronomical writing that we have is Tablet 63 of the Enuma Anu Enlil. It is called the Venus tablet of Ammi-saduqa. The Venus tablet lists the first and last visible risings of Venus over a period of about 21 years, and it is the earliest conclusive evidence that the phenomena of a planet were recognized.
Since the beginning of time, man has looked up. The sky, particularly the night sky, has been full of mystery that humankind wanted to understand.
The old civilizations of China, India, Greece, and Rome all looked to the stars for explanations to earthly situations and problems, inspiration and guidance. They found all of those things, but they also found knowledge, and over the centuries our knowledge of astronomy has grown. But there are those who believe that we have only just begun to learn all the heavens have to teach us.
Related Topics: The Planet Saturn,
The Planet Saturn, Astronomy Clubs
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