Stars and Constellations Physics 113 Goderya Chapter(s): 2 Learning Outcome:
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Transcript of Stars and Constellations Physics 113 Goderya Chapter(s): 2 Learning Outcome:
Stars and ConstellationsPhysics 113 Goderya
Chapter(s): 2Learning Outcome:
Constellations
In ancient times, constellations only referred to the brightest stars that appeared to form
groups, representing mythological figures.
Finding objects in the sky
• Constellations
Source: Jodrell Bank Observatory
Finding objects in the sky
• Orion Nebula
Source: Jodrell Bank Observatory
Constellations (2)
Today, constellations are well-defined regions on the sky, irrespective of the presence or absence of bright stars in those regions.
Apparent viewThe stars of a constellation only appear to be close to one another
Usually, this is only a projection effect.
The stars of a constellation may be located at very different distances from us.
Star NamesStars are named by a Greek letter () according to their relative brightness within a given constellation + the possessive form of the name of the constellation:
OrionBetelgeuze
Rigel
Betelgeuse = OrionisRigel = Orionis
Circumpolar Constellations
Non Circumpolar Constellations
Constellation of the ZodiacDue to Earth’s revolution around the sun, the sun appears to move through the zodiacal constellations.
Constellations from Different Places
(SLIDESHOW MODE ONLY)
Stellariumhttp://www.stellarium.org
Go download it if you have a computer at home. Its Free
Source: Jodrell Bank Observatory Screen from STELLARIUM (A freeware software)
Angles in Astronomy
• Angles– Circle = 360º =2π radians– Two Perpendicular lines = 90º– 1º = 60 ‘ (arc minutes)– 1‘ = 60 " (arc seconds)– 1 radian = 360x60x60/2π = 206265 "– Sun & Moon Diameter = 0.5º = 30 “– Extended fist = 5º
Angles in Astronomy
Small Angle Formula
distance
diameterlinear
5206,26
diameterangular
km 384,000
km 3476
5206,26
diameterangular
5.06060
18700187diameterangular
Example for Moon