Copy and Answer in NB

1. What are the three layers of the suns atmosphere?

2. What produces auroras?3. What are sunspots and why are they dark?4. Describe solar flares and prominences. 5. How does the sun produce energy and

where does this process take place?

Measuring StarsWhat is the fate of our sun

and other stars?

Star Groups

• Constellation – Group of stars that form a pattern in the sky that resembles an animal or mythological character

• Seen at different times of the year

Orion’s Belt

Star Groups• Cluster – Group of stars gravitationally bound

to each other• Some are densely packed (globular) and some

are loosely packed (open)

Star Groups• Binary Star – two stars that are gravitationally

bound to each other and orbit a common center of mass (ex: Sirius)– Can appear to be one star to the human eye

Units of Distance

• Light Year (ly) – Distance light travels in one year– 9.461 x 1012km

• Parsec (pc) – 3.26 ly or 3.086 x 1013km

Parallax

• The apparent shift in position caused by the motion of the observer

• The closer the star, the larger the shift

Basic Properties of Stars

• Apparent Magnitude – How bright a star appears to be

• Absolute Magnitude– Brightness an object would have if it were placed

at a distance of 10pc– Calculates for equal distance– Can only be used if stars distance is known

Basic Properties of Stars

• Luminosity – Energy output from

the surface of a star per second

– Measured in Watts– Must know distance

of star and apparent magnitude

Hertzsprung Russell Diagram

• H-R Diagram – graph that organizes stellar characteristics (By temp and luminosity)

• Main Sequence – runs diagonally from the upper left corner, hot luminous stars, to lower right corner, cool dim stars– 90% of all stars, including the Sun

Hertzsprung Russell Diagram

• Red Giant – Cool, Luminous Star – Upper Right hand corner of H-R diagram

• White Dwarf – Dim, hot star – Lower Left hand corner of H-R diagram