Download A star is a - Trimble County Schools

29.2 - Stars
Star
• A star is a ___________________________________________
________________________________________________________________________
•
•
Appear to be tiny specks of white light
Most vary in color and are much larger than Earth
Motion
• Stars move through the night sky towards the west
• Stars rotate around the North Star, Polaris
– _____________________________ = stars that circle around Polaris
• Because of the earth’s rotation, some stars are not visible during particular seasons
Constellations
• _____________________________
• Location changes throughout the year due to Earth’s orbit
– _____________________________n
• 3000 years ago, people observed and recorded shifting patterns
– Knew when to plant, harvest, and celebrate rituals based on location of
constellations
Constellations
• Astronomers recognize _____________________________
• Constellations are named for ____________________________
__________________________________________________________
– Most do not look like what they are named for
Common Constellations
• Ursa Major (Big Dipper)
• Ursa Minor (Little Dipper)
• Draco the Dragon
• Orion
• Zodiac Animals
Constellation stars
• Astronomers use constellations to locate _____________________________
• Stars within a constellation are named according to
_____________________________
– Brightest star is labeled alpha
– Next brightest beta and so on
• Some constellation stars have individual names
– Polaris (North star) in the Little Dipper
Star Clusters
• _____________________________________________________________________
__________________ cannot distinguish the distance a star is from earth
• Clusters are stars close to each other due to gravitational attraction
Binary Stars
• _____________________________
– Pairs of stars that revolve around one another
– Gravitationally bound & orbiting a common center of mass
• Used to determine _____________________________
• Appear as a single star to the human eye
Distance
• Astronomers use different methods to measure the distance between stars and Earth
Distance to Stars
• Distance to stars from Earth is measured in Light-years
– Light-year = ______________________________________________
– Light-year = 9.461 x 1015 m
Light
• Light travels 9.5 trillion km in one year
– Speed of light = 300,000 km/s
– Sun is 8 light-minutes away because it takes 8 minutes for the sunlight to reach
Earth
• Parsec = _____________________________= 3.086 x1016 m
Parallax
• ____________________________________________________ caused by motion of
observer
• Change in position of Earth as it orbits
– Closer stars have larger change in parallax
– Farther stars have smaller change in parallax
• Distance determined by angle of change