Transcript Astronomy - Dr. Noha MH Elnagdi

Astronomy
Science combining all sciences
What is the Science of
Astronomy?
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Astronomy is the scientific study of
celestial objects (such as stars,
planets, comets, and galaxies) and
phenomena that originate outside the
Earth's atmosphere (such as the
cosmic background radiation). It is
concerned with the evolution, physics,
chemistry, meteorology, and motion of
celestial objects, as well as the
formation and development of the
universe
Subfield of astronomy for specific
astronomical objects
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Solar astronomy
Planetary science
Stellar astronomy (Star formation )
Galactic astronomy
Extragalactic astronomy
Cosmology (the study of the universe as a whole)
Tools of Astronomy
Telescopes
Optical Telescopes
Nonoptical
Telescopes
Optical Telescopes
Optical telescopes are the most used,
and they are of several kinds:
 Reflecting Telescopes.
 Refracting Telescopes.
Non-optical telescopes:
 Radio telescopes.
 Infrared Telescopes.
 X-ray Telescopes.
 Gamma ray Telescopes.
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Comparing between Reflecting Telescope and
Refracting Telescope
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Very large reflecting
telescopes:
Optical Telescopes in space.
(The Hubble Telescope)
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Radio Telescope: Radio
telescope is an astronomical
instrument consisting of a radio
receiver and an antenna system
that is used to detect radiofrequency radiation emitted by
extraterrestrial sources.
Because radio wavelengths are
much longer than those of
visible light, radio telescopes
must be very large in order to
attain the resolution of optical
telescopes.
Connecting radio
telescopes
Comparing images from
different tools
Why Do Stars Twinkle?
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The scientific name for the twinkling of
stars is stellar scintillation (or
astronomical scintillation)
Stars twinkle when we observe them from
the Earth's surface
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Stars closer to the horizon appear to
twinkle more than stars that
are overhead
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While traveling through the Earth's atmosphere,
the light of the star is bent (refracted) many
times in random directions by changes in
atmospheric density (like a pocket of cold air or
hot air) and this random refraction results in the
star winking out
Planets usually do not twinkle they are (appear)
big enough that this effect is not noticeable
(unless when the air is extremely turbulent)
Assignment
In a table form, compare between
Reflecting Telescope and Refracting
Telescope, using illustrations as well.
 Notes:
1- you have to draw yourself using a
pencil and a ruler
2- Comparison must include the
structure, advantages, and
disadvantages of each type
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